Most effective defense against insecure deserialization

OWASP Top 10 - 2017 The Ten Most Critical Web Application Security Risks

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Table of Contents About OWASP

The Open Web Application Security Project (OWASP) is an

open community dedicated to enabling organizations to

develop, purchase, and maintain applications and APIs that

can be trusted.

At OWASP, you'll find free and open:

• Application security tools and standards.

• Complete books on application security testing, secure code development, and secure code review.

• Presentations and videos. • Cheat sheets on many common topics. • Standard security controls and libraries. • Local chapters worldwide. • Cutting edge research. • Extensive conferences worldwide. • Mailing lists.

Learn more at: https://www.owasp.org.

All OWASP tools, documents, videos, presentations, and

chapters are free and open to anyone interested in improving

application security.

We advocate approaching application security as a people,

process, and technology problem, because the most

effective approaches to application security require

improvements in these areas.

OWASP is a new kind of organization. Our freedom from

commercial pressures allows us to provide unbiased,

practical, and cost-effective information about application

security.

OWASP is not affiliated with any technology company,

although we support the informed use of commercial security

technology. OWASP produces many types of materials in a

collaborative, transparent, and open way.

The OWASP Foundation is the non-profit entity that ensures

the project's long-term success. Almost everyone associated

with OWASP is a volunteer, including the OWASP board,

chapter leaders, project leaders, and project members.

We support innovative security research with grants and

infrastructure.

Come join us!

TOC Table of Contents

TOC - About OWASP ……………………………… 1

FW - Foreword …………..………………...……… 2

I - Introduction ………..……………….……..… 3

RN - Release Notes …………..………….…..….. 4

Risk - Application Security Risks…………….…… 5

T10 - OWASP Top 10 Application Security

Risks – 2017 …………..……….....….…… 6

A1:2017 - Injection …….………..……………………… 7

A2:2017 - Broken Authentication ……………………... 8

A3:2017 - Sensitive Data Exposure ………………….. 9

A4:2017 - XML External Entities (XXE) ……………... 10

A5:2017 - Broken Access Control ……………...…….. 11

A6:2017 - Security Misconfiguration ………………….. 12

A7:2017 - Cross-Site Scripting (XSS) ….…………….. 13

A8:2017 - Insecure Deserialization ……………………14

A9:2017 - Using Components with Known

Vulnerabilities .……………………………… 15

A10:2017 - Insufficient Logging & Monitoring….…..….. 16

+D - What’s Next for Developers ….………..….. 17

+T - What’s Next for Security Testers .……..….. 18

+O - What’s Next for Organizations ….....…….... 19

+A - What’s Next for Application Managers ...... 20

+R - Note About Risks ……..……………………. 21

+RF - Details About Risk Factors ……………..…. 22

+DAT - Methodology and Data …..………………… 23

+ACK - Acknowledgements ………………..………. 24

http://creativecommons.org/licenses/by-sa/3.0/
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https://www.owasp.org/index.php/OWASP_Cheat_Sheet_Series
https://www.owasp.org/index.php/OWASP_Chapter
https://www.owasp.org/index.php/Category:OWASP_AppSec_Conference
https://lists.owasp.org/mailman/listinfo
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2

Foreword

Insecure software is undermining our financial, healthcare, defense, energy, and other critical infrastructure. As our software

becomes increasingly complex, and connected, the difficulty of achieving application security increases exponentially. The

rapid pace of modern software development processes makes the most common risks essential to discover and resolve

quickly and accurately. We can no longer afford to tolerate relatively simple security problems like those presented in this

OWASP Top 10.

A great deal of feedback was received during the creation of the OWASP Top 10 - 2017, more than for any other equivalent

OWASP effort. This shows how much passion the community has for the OWASP Top 10, and thus how critical it is for

OWASP to get the Top 10 right for the majority of use cases.

Although the original goal of the OWASP Top 10 project was simply to raise awareness amongst developers and managers,

it has become the de facto application security standard.

In this release, issues and recommendations are written concisely and in a testable way to assist with the adoption of the

OWASP Top 10 in application security programs. We encourage large and high performing organizations to use the OWASP

Application Security Verification Standard (ASVS) if a true standard is required, but for most, the OWASP Top 10 is a great

start on the application security journey.

We have written up a range of suggested next steps for different users of the OWASP Top 10, including What’s Next for

Developers, What’s Next for Security Testers, What’s Next for Organizations, which is suitable for CIOs and CISOs, and

What’s Next for Application Managers, which is suitable for application managers or anyone responsible for the lifecycle of

the application.

In the long term, we encourage all software development teams and organizations to create an application security program

that is compatible with your culture and technology. These programs come in all shapes and sizes. Leverage your

organization's existing strengths to measure and improve your application security program using the Software Assurance

Maturity Model.

We hope that the OWASP Top 10 is useful to your application security efforts. Please don't hesitate to contact OWASP with

your questions, comments, and ideas at our GitHub project repository:

• https://github.com/OWASP/Top10/issues

You can find the OWASP Top 10 project and translations here:

• https://www.owasp.org/index.php/top10

Lastly, we wish to thank the founding leadership of the OWASP Top 10 project, Dave Wichers and Jeff Williams, for all their

efforts, and believing in us to get this finished with the community's help. Thank you!

• Andrew van der Stock

• Brian Glas

• Neil Smithline

• Torsten Gigler

Project Sponsorship

Thanks to Autodesk for sponsoring the OWASP Top 10 - 2017.

Organizations and individuals that have provided vulnerability prevalence data or other assistance are listed on the

Acknowledgements page.

FW Foreword

https://www.owasp.org/index.php/Category:OWASP_Application_Security_Verification_Standard_Project
https://www.owasp.org/index.php/OWASP_SAMM_Project
https://github.com/OWASP/Top10/issues
https://www.owasp.org/index.php/top10
https://www.autodesk.com/
3

Welcome to the OWASP Top 10 - 2017!

This major update adds several new issues, including two issues selected by the community - A8:2017-Insecure

Deserialization and A10:2017-Insufficient Logging and Monitoring. Two key differentiators from previous OWASP Top 10

releases are the substantial community feedback and extensive data assembled from dozens of organizations, possibly the

largest amount of data ever assembled in the preparation of an application security standard. This provides us with

confidence that the new OWASP Top 10 addresses the most impactful application security risks currently facing

organizations.

The OWASP Top 10 - 2017 is based primarily on 40+ data submissions from firms that specialize in application security and

an industry survey that was completed by over 500 individuals. This data spans vulnerabilities gathered from hundreds of

organizations and over 100,000 real-world applications and APIs. The Top 10 items are selected and prioritized according to

this prevalence data, in combination with consensus estimates of exploitability, detectability, and impact.

A primary aim of the OWASP Top 10 is to educate developers, designers, architects, managers, and organizations about the

consequences of the most common and most important web application security weaknesses. The Top 10 provides basic

techniques to protect against these high risk problem areas, and provides guidance on where to go from here.

Roadmap for future activities

Don't stop at 10. There are hundreds of issues that could

affect the overall security of a web application as discussed

in the OWASP Developer's Guide and the OWASP Cheat

Sheet Series. These are essential reading for anyone

developing web applications and APIs. Guidance on how to

effectively find vulnerabilities in web applications and APIs

is provided in the OWASP Testing Guide.

Constant change. The OWASP Top 10 will continue to

change. Even without changing a single line of your

application's code, you may become vulnerable as new

flaws are discovered and attack methods are refined.

Please review the advice at the end of the Top 10 in What's

Next For Developers, Security Testers, Organizations, and

Application Managers for more information.

Think positive. When you're ready to stop chasing

vulnerabilities and focus on establishing strong application

security controls, the OWASP Proactive Controls project

provides a starting point to help developers build security

into their application and the OWASP Application Security

Verification Standard (ASVS) is a guide for organizations

and application reviewers on what to verify.

Use tools wisely. Security vulnerabilities can be quite

complex and deeply buried in code. In many cases, the

most cost-effective approach for finding and eliminating

these weaknesses is human experts armed with advanced

tools. Relying on tools alone provides a false sense of

security and is not recommended.

Push left, right, and everywhere. Focus on making

security an integral part of your culture throughout your

development organization. Find out more in the OWASP

Software Assurance Maturity Model (SAMM).

Attribution

We'd like to thank the organizations that contributed their

vulnerability data to support the 2017 update. We received

more than 40 responses to the call for data. For the first

time, all the data contributed to a Top 10 release, and the full

list of contributors is publicly available. We believe this is one

of the larger, more diverse collections of vulnerability data

ever publicly collected.

As there are more contributors than space here, we have

created a dedicated page to recognize the contributions

made. We wish to give heartfelt thanks to these

organizations for being willing to be on the front lines by

publicly sharing vulnerability data from their efforts. We hope

this will continue to grow and encourage more organizations

to do the same and possibly be seen as one of the key

milestones of evidence-based security. The OWASP Top 10 would not be possible without these amazing contributions.

A big thank you to the more than 500 individuals who took

the time to complete the industry ranked survey. Your voice

helped determine two new additions to the Top 10. The

additional comments, notes of encouragement,

and criticisms were all appreciated. We know your time is

valuable and we wanted to say thanks.

We would like to thank those individuals who have

contributed significant constructive comments and time

reviewing this update to the Top 10. As much as possible,

we have listed them on the ‘Acknowledgements’ page.

And finally, we'd like to thank in advance all the translators

out there who will translate this release of the Top 10 into

numerous different languages, helping to make the OWASP

Top 10 more accessible to the entire planet.

I Introduction

https://www.owasp.org/index.php/OWASP_Guide_Project
https://www.owasp.org/index.php/OWASP_Cheat_Sheet_Series
https://www.owasp.org/index.php/OWASP_Testing_Project
https://www.owasp.org/index.php/OWASP_Proactive_Controls
https://www.owasp.org/index.php/ASVS
https://www.owasp.org/index.php/OWASP_SAMM_Project
4

What changed from 2013 to 2017? Change has accelerated over the last four years, and the OWASP Top 10 needed to change. We've completely refactored the OWASP Top 10, revamped the methodology, utilized a new data call process, worked with the community, re-ordered our risks, re- written each risk from the ground up, and added references to frameworks and languages that are now commonly used.

Over the last few years, the fundamental technology and architecture of applications has changed significantly:

• Microservices written in node.js and Spring Boot are replacing traditional monolithic applications. Microservices come with their own security challenges including establishing trust between microservices, containers, secret management, etc. Old code never expected to be accessible from the Internet is now sitting behind an API or RESTful web service to be consumed by Single Page Applications (SPAs) and mobile applications. Architectural assumptions by the code, such as trusted callers, are no longer valid.

• Single page applications, written in JavaScript frameworks such as Angular and React, allow the creation of highly modular feature-rich front ends. Client-side functionality that has traditionally been delivered server-side brings its own security challenges.

• JavaScript is now the primary language of the web with node.js running server side and modern web frameworks such as Bootstrap, Electron, Angular, and React running on the client.

New issues, supported by data:

• A4:2017-XML External Entities (XXE) is a new category primarily supported by source code analysis security testing tools (SAST) data sets.

New issues, supported by the community:

We asked the community to provide insight into two forward looking weakness categories. After over 500 peer submissions, and removing issues that were already supported by data (such as Sensitive Data Exposure and XXE), the two new issues are:

• A8:2017-Insecure Deserialization, which permits remote code execution or sensitive object manipulation on affected platforms.

• A10:2017-Insufficient Logging and Monitoring, the lack of which can prevent or significantly delay malicious activity and breach detection, incident response, and digital forensics.

Merged or retired, but not forgotten:

• A4-Insecure Direct Object References and A7-Missing Function Level Access Control merged into A5:2017-Broken Access Control.

• A8-Cross-Site Request Forgery (CSRF), as many frameworks include CSRF defenses, it was found in only 5% of applications.

• A10-Unvalidated Redirects and Forwards, while found in approximately 8% of applications, it was edged out overall by XXE.

OWASP Top 10 - 2013  OWASP Top 10 - 2017

A1 – Injection  A1:2017-Injection

A2 – Broken Authentication and Session Management  A2:2017-Broken Authentication

A3 – Cross-Site Scripting (XSS)  A3:2017-Sensitive Data Exposure

A4 – Insecure Direct Object References [Merged+A7] ∪ A4:2017-XML External Entities (XXE) [NEW]

A5 – Security Misconfiguration  A5:2017-Broken Access Control [Merged]

A6 – Sensitive Data Exposure  A6:2017-Security Misconfiguration

A7 – Missing Function Level Access Contr [Merged+A4] ∪ A7:2017-Cross-Site Scripting (XSS)

A8 – Cross-Site Request Forgery (CSRF)  A8:2017-Insecure Deserialization [NEW, Community]

A9 – Using Components with Known Vulnerabilities  A9:2017-Using Components with Known Vulnerabilities

A10 – Unvalidated Redirects and Forwards  A10:2017-Insufficient Logging&Monitoring [NEW,Comm.]

RN Release Notes

https://www.owasp.org/index.php/Source_Code_Analysis_Tools
https://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)
5

What Are Application Security Risks? Attackers can potentially use many different paths through your application to do harm to your business or organization. Each of these paths represents a risk that may, or may not, be serious enough to warrant attention.

Sometimes these paths are trivial to find and exploit, and sometimes they are extremely difficult. Similarly, the harm that is caused may be of no consequence, or it may put you out of business. To determine the risk to your organization, you can evaluate the likelihood associated with each threat agent, attack vector, and security weakness and combine it with an estimate of the technical and business impact to your organization. Together, these factors determine your overall risk.

Weakness

Attack

Threat Agents

ImpactWeakness

Attack

Attack Vectors

Security Weaknesses

Technical Impacts

Business Impacts

Attack

Impact

Impact

Asset

Function

Asset

Weakness

Control

Control

ControlWeakness

Security Controls

Risk Application Security Risks

What’s My Risk? The OWASP Top 10 focuses on identifying the most serious web application security risks for a broad array of organizations. For each of these risks, we provide generic information about likelihood and technical impact using the following simple ratings scheme, which is based on the OWASP Risk Rating Methodology.

In this edition, we have updated the risk rating system to assist in calculating the likelihood and impact of any given risk. For more details, please see Note About Risks.

Each organization is unique, and so are the threat actors for that organization, their goals, and the impact of any breach. If a public interest organization uses a content management system (CMS) for public information and a health system uses that same exact CMS for sensitive health records, the threat actors and business impacts can be very different for the same software. It is critical to understand the risk to your organization based on applicable threat agents and business impacts.

Where possible, the names of the risks in the Top 10 are aligned with Common Weakness Enumeration (CWE) weaknesses to promote generally accepted naming conventions and to reduce confusion.

Threat

Agents Exploitability

Weakness

Prevalence

Weakness

Detectability

Technical

Impacts

Business

Impacts

Appli-

cation

Specific

Easy: 3 Widespread: 3 Easy: 3 Severe: 3

Business

Specific Average: 2 Common: 2 Average: 2 Moderate: 2

Difficult: 1 Uncommon: 1 Difficult: 1 Minor: 1

References

OWASP

• OWASP Risk Rating Methodology

• Article on Threat/Risk Modeling

External

• ISO 31000: Risk Management Std

• ISO 27001: ISMS

• NIST Cyber Framework (US)

• ASD Strategic Mitigations (AU)

• NIST CVSS 3.0

• Microsoft Threat Modelling Tool

https://www.owasp.org/index.php/Top_10
https://www.owasp.org/index.php/OWASP_Risk_Rating_Methodology
https://cwe.mitre.org/data/definitions/22.html
https://www.owasp.org/index.php/OWASP_Risk_Rating_Methodology
https://www.owasp.org/index.php/Threat_Risk_Modeling
https://www.iso.org/iso-31000-risk-management.html
https://www.iso.org/isoiec-27001-information-security.html
https://www.nist.gov/cyberframework
https://www.asd.gov.au/infosec/mitigationstrategies.htm
https://nvd.nist.gov/vuln-metrics/cvss/v3-calculator
https://www.microsoft.com/en-us/download/details.aspx?id=49168
6

T10 OWASP Top 10Application Security Risks – 2017 Injection flaws, such as SQL, NoSQL, OS, and LDAP injection, occur when untrusted data is sent to an interpreter as part of a command or query. The attacker’s hostile data can trick the interpreter into executing unintended commands or accessing data without proper authorization.

A1:2017- Injection

Application functions related to authentication and session management are often implemented incorrectly, allowing attackers to compromise passwords, keys, or session tokens, or to exploit other implementation flaws to assume other users’ identities temporarily or permanently.

A2:2017-Broken Authentication

Many web applications and APIs do not properly protect sensitive data, such as financial, healthcare, and PII. Attackers may steal or modify such weakly protected data to conduct credit card fraud, identity theft, or other crimes. Sensitive data may be compromised without extra protection, such as encryption at rest or in transit, and requires special precautions when exchanged with the browser.

A3:2017- Sensitive Data

Exposure

Many older or poorly configured XML processors evaluate external entity references within XML documents. External entities can be used to disclose internal files using the file URI handler, internal file shares, internal port scanning, remote code execution, and denial of service attacks.

A4:2017-XML External

Entities (XXE)

Restrictions on what authenticated users are allowed to do are often not properly enforced. Attackers can exploit these flaws to access unauthorized functionality and/or data, such as access other users' accounts, view sensitive files, modify other users’ data, change access rights, etc.

A5:2017-Broken Access Control

Security misconfiguration is the most commonly seen issue. This is commonly a result of insecure default configurations, incomplete or ad hoc configurations, open cloud storage, misconfigured HTTP headers, and verbose error messages containing sensitive information. Not only must all operating systems, frameworks, libraries, and applications be securely configured, but they must be patched and upgraded in a timely fashion.

XSS flaws occur whenever an application includes untrusted data in a new web page without proper validation or escaping, or updates an existing web page with user-supplied data using a browser API that can create HTML or JavaScript. XSS allows attackers to execute scripts in the victim’s browser which can hijack user sessions, deface web sites, or redirect the user to malicious sites.

A7:2017- Cross-Site

Scripting (XSS)

Insecure deserialization often leads to remote code execution. Even if deserialization flaws do not result in remote code execution, they can be used to perform attacks, including replay attacks, injection attacks, and privilege escalation attacks.

A8:2017- Insecure

Deserialization

Components, such as libraries, frameworks, and other software modules, run with the same privileges as the application. If a vulnerable component is exploited, such an attack can facilitate serious data loss or server takeover. Applications and APIs using components with known vulnerabilities may undermine application defenses and enable various attacks and impacts.

A9:2017-Using Components with Known

Vulnerabilities

Insufficient logging and monitoring, coupled with missing or ineffective integration with incident response, allows attackers to further attack systems, maintain persistence, pivot to more systems, and tamper, extract, or destroy data. Most breach studies show time to detect a breach is over 200 days, typically detected by external parties rather than internal processes or monitoring.

A10:2017- Insufficient Logging & Monitoring

A6:2017-Security

Misconfiguration

App. Specific Business ?

7

Impacts Threat

Agents Attack

Vectors

Security

Weakness

Example Attack Scenarios Scenario #1: An application uses untrusted data in the construction of the following vulnerable SQL call:

String query = "SELECT * FROM accounts WHERE custID='" + request.getParameter("id") + "'";

Scenario #2: Similarly, an application’s blind trust in frameworks may result in queries that are still vulnerable, (e.g. Hibernate Query Language (HQL)):

Query HQLQuery = session.createQuery("FROM accounts WHERE custID='" + request.getParameter("id") + "'");

In both cases, the attacker modifies the ‘id’ parameter value in their browser to send: ' or '1'='1. For example:

http://example.com/app/accountView?id=' or '1'='1

This changes the meaning of both queries to return all the records from the accounts table. More dangerous attacks could modify or delete data, or even invoke stored procedures.

Is the Application Vulnerable? An application is vulnerable to attack when:

• User-supplied data is not validated, filtered, or sanitized by the application.

• Dynamic queries or non-parameterized calls without context- aware escaping are used directly in the interpreter.

• Hostile data is used within object-relational mapping (ORM) search parameters to extract additional, sensitive records.

• Hostile data is directly used or concatenated, such that the SQL or command contains both structure and hostile data in dynamic queries, commands, or stored procedures.

Some of the more common injections are SQL, NoSQL, OS command, Object Relational Mapping (ORM), LDAP, and Expression Language (EL) or Object Graph Navigation Library (OGNL) injection. The concept is identical among all interpreters. Source code review is the best method of detecting if applications are vulnerable to injections, closely followed by thorough automated testing of all parameters, headers, URL, cookies, JSON, SOAP, and XML data inputs. Organizations can include static source (SAST) and dynamic application test (DAST) tools into the CI/CD pipeline to identify newly introduced injection flaws prior to production deployment.

References OWASP • OWASP Proactive Controls: Parameterize Queries

• OWASP ASVS: V5 Input Validation and Encoding

• OWASP Testing Guide: SQL Injection, Command Injection, ORM injection

• OWASP Cheat Sheet: Injection Prevention

• OWASP Cheat Sheet: SQL Injection Prevention

• OWASP Cheat Sheet: Injection Prevention in Java

• OWASP Cheat Sheet: Query Parameterization

• OWASP Automated Threats to Web Applications – OAT-014

External • CWE-77: Command Injection

• CWE-89: SQL Injection

• CWE-564: Hibernate Injection

• CWE-917: Expression Language Injection

• PortSwigger: Server-side template injection

How to Prevent Preventing injection requires keeping data separate from commands and queries.

• The preferred option is to use a safe API, which avoids the use of the interpreter entirely or provides a parameterized interface, or migrate to use Object Relational Mapping Tools (ORMs). Note: Even when parameterized, stored procedures can still introduce SQL injection if PL/SQL or T-SQL concatenates queries and data, or executes hostile data with EXECUTE IMMEDIATE or exec().

• Use positive or "whitelist" server-side input validation. This is not a complete defense as many applications require special characters, such as text areas or APIs for mobile applications.

• For any residual dynamic queries, escape special characters using the specific escape syntax for that interpreter. Note: SQL structure such as table names, column names, and so on cannot be escaped, and thus user-supplied structure names are dangerous. This is a common issue in report-writing software.

• Use LIMIT and other SQL controls within queries to prevent mass disclosure of records in case of SQL injection.

A1 :2017

Injection

Exploitability: 3 Prevalence: 2 Detectability: 3 Technical: 3

Almost any source of data can be an injection vector, environment variables, parameters, external and internal web services, and all types of users. Injection flaws occur when an attacker can send hostile data to an interpreter.

Injection flaws are very prevalent, particularly in legacy code. Injection vulnerabilities are often found in SQL, LDAP, XPath, or NoSQL queries, OS commands, XML parsers, SMTP headers, expression languages, and ORM queries.

Injection flaws are easy to discover when examining code. Scanners and fuzzers can help attackers find injection flaws.

Injection can result in data loss, corruption, or disclosure to unauthorized parties, loss of accountability, or denial of access. Injection can sometimes lead to complete host takeover.

The business impact depends on the needs of the application and data.

https://www.owasp.org/index.php/Source_Code_Analysis_Tools
https://www.owasp.org/index.php/Category:Vulnerability_Scanning_Tools
https://www.owasp.org/index.php/OWASP_Proactive_Controls#2:_Parameterize_Queries
https://www.owasp.org/index.php/ASVS_V5_Input_validation_and_output_encoding
https://www.owasp.org/index.php/Testing_for_SQL_Injection_(OTG-INPVAL-005)
https://www.owasp.org/index.php/Testing_for_Command_Injection_(OTG-INPVAL-013)
https://www.owasp.org/index.php/Testing_for_ORM_Injection_(OTG-INPVAL-007)
https://www.owasp.org/index.php/Injection_Prevention_Cheat_Sheet
https://www.owasp.org/index.php/SQL_Injection_Prevention_Cheat_Sheet
https://www.owasp.org/index.php/Injection_Prevention_Cheat_Sheet_in_Java
https://www.owasp.org/index.php/Query_Parameterization_Cheat_Sheet
https://www.owasp.org/index.php/OWASP_Automated_Threats_to_Web_Applications
https://cwe.mitre.org/data/definitions/77.html
https://cwe.mitre.org/data/definitions/89.html
https://cwe.mitre.org/data/definitions/564.html
https://cwe.mitre.org/data/definitions/917.html
https://portswigger.net/kb/issues/00101080_serversidetemplateinjection
(https:/portswigger.net/kb/issues/00101080_serversidetemplateinjection)
https://www.owasp.org/index.php/Injection_Flaws
App. Specific Business ?

8

Impacts Threat

Agents Attack

Vectors

Security

Weakness

Example Attack Scenarios Scenario #1: Credential stuffing, the use of lists of known passwords, is a common attack. If an application does not implement automated threat or credential stuffing protections, the application can be used as a password oracle to determine if the credentials are valid.

Scenario #2: Most authentication attacks occur due to the continued use of passwords as a sole factor. Once considered best practices, password rotation and complexity requirements are viewed as encouraging users to use, and reuse, weak passwords. Organizations are recommended to stop these practices per NIST 800-63 and use multi-factor authentication.

Scenario #3: Application session timeouts aren’t set properly. A user uses a public computer to access an application. Instead of selecting “logout” the user simply closes the browser tab and walks away. An attacker uses the same browser an hour later, and the user is still authenticated.

Is the Application Vulnerable? Confirmation of the user's identity, authentication, and session management are critical to protect against authentication-related attacks.

There may be authentication weaknesses if the application:

• Permits automated attacks such as credential stuffing, where the attacker has a list of valid usernames and passwords.

• Permits brute force or other automated attacks.

• Permits default, weak, or well-known passwords, such as "Password1" or "admin/admin“.

• Uses weak or ineffective credential recovery and forgot- password processes, such as "knowledge-based answers", which cannot be made safe.

• Uses plain text, encrypted, or weakly hashed passwords (see A3:2017-Sensitive Data Exposure).

• Has missing or ineffective multi-factor authentication.

• Exposes Session IDs in the URL (e.g., URL rewriting).

• Does not rotate Session IDs after successful login.

• Does not properly invalidate Session IDs. User sessions or authentication tokens (particularly single sign-on (SSO) tokens) aren’t properly invalidated during logout or a period of inactivity.

References OWASP • OWASP Proactive Controls: Implement Identity and

Authentication Controls

• OWASP ASVS: V2 Authentication, V3 Session Management

• OWASP Testing Guide: Identity, Authentication

• OWASP Cheat Sheet: Authentication

• OWASP Cheat Sheet: Credential Stuffing

• OWASP Cheat Sheet: Forgot Password

• OWASP Cheat Sheet: Session Management

• OWASP Automated Threats Handbook

External • NIST 800-63b: 5.1.1 Memorized Secrets

• CWE-287: Improper Authentication

• CWE-384: Session Fixation

How to Prevent • Where possible, implement multi-factor authentication to

prevent automated, credential stuffing, brute force, and stolen credential re-use attacks.

• Do not ship or deploy with any default credentials, particularly for admin users.

• Implement weak-password checks, such as testing new or changed passwords against a list of the top 10000 worst passwords.

• Align password length, complexity and rotation policies with NIST 800-63 B's guidelines in section 5.1.1 for Memorized Secrets or other modern, evidence based password policies.

• Ensure registration, credential recovery, and API pathways are hardened against account enumeration attacks by using the same messages for all outcomes.

• Limit or increasingly delay failed login attempts. Log all failures and alert administrators when credential stuffing, brute force, or other attacks are detected.

• Use a server-side, secure, built-in session manager that generates a new random session ID with high entropy after login. Session IDs should not be in the URL, be securely stored and invalidated after logout, idle, and absolute timeouts.

A2 :2017

Broken Authentication

Exploitability: 3 Prevalence: 2 Detectability: 2 Technical: 3

Attackers have access to hundreds of millions of valid username and password combinations for credential stuffing, default administrative account lists, automated brute force, and dictionary attack tools. Session management attacks are well understood, particularly in relation to unexpired session tokens.

The prevalence of broken authentication is widespread due to the design and implementation of most identity and access controls. Session manage- ment is the bedrock of authentication and access controls, and is present in all stateful applications.

Attackers can detect broken authentication using manual means and exploit them using automated tools with password lists and dictionary attacks.

Attackers have to gain access to only

a few accounts, or just one admin

account to compromise the system.

Depending on the domain of the

application, this may allow money

laundering, social security fraud, and

identity theft, or disclose legally

protected highly sensitive information.

https://www.owasp.org/index.php/Credential_stuffing
https://github.com/danielmiessler/SecLists
https://www.owasp.org/index.php/Credential_stuffing
https://www.owasp.org/index.php/OWASP_Proactive_Controls#5:_Implement_Identity_and_Authentication_Controls
http:// Authentication
https://www.owasp.org/index.php/Category:OWASP_Application_Security_Verification_Standard_Project#tab=Home
https://www.owasp.org/index.php/Testing_Identity_Management
https://www.owasp.org/index.php/Testing_for_authentication
https://www.owasp.org/index.php/Authentication_Cheat_Sheet
https://www.owasp.org/index.php/Credential_Stuffing_Prevention_Cheat_Sheet
https://www.owasp.org/index.php/Forgot_Password_Cheat_Sheet
https://www.owasp.org/index.php/Credential_Stuffing_Prevention_Cheat_Sheet
https://www.owasp.org/index.php/Forgot_Password_Cheat_Sheet
https://www.owasp.org/index.php/OWASP_Automated_Threats_to_Web_Applications
https://www.owasp.org/index.php/OWASP_Automated_Threats_to_Web_Applications
https://pages.nist.gov/800-63-3/sp800-63b.html#memsecret
https://cwe.mitre.org/data/definitions/287.html
https://cwe.mitre.org/data/definitions/384.html
https://github.com/danielmiessler/SecLists/tree/master/Passwords
https://pages.nist.gov/800-63-3/sp800-63b.html#memsecret
App. Specific Business ?

9

Impacts Threat

Agents Attack

Vectors

Security

Weakness

Example Attack Scenarios Scenario #1: An application encrypts credit card numbers in a database using automatic database encryption. However, this data is automatically decrypted when retrieved, allowing an SQL injection flaw to retrieve credit card numbers in clear text.

Scenario #2: A site doesn't use or enforce TLS for all pages or supports weak encryption. An attacker monitors network traffic (e.g. at an insecure wireless network), downgrades connections from HTTPS to HTTP, intercepts requests, and steals the user's session cookie. The attacker then replays this cookie and hijacks the user's (authenticated) session, accessing or modifying the user's private data. Instead of the above they could alter all transported data, e.g. the recipient of a money transfer.

Scenario #3: The password database uses unsalted or simple hashes to store everyone's passwords. A file upload flaw allows an attacker to retrieve the password database. All the unsalted hashes can be exposed with a rainbow table of pre-calculated hashes. Hashes generated by simple or fast hash functions may be cracked by GPUs, even if they were salted.

Is the Application Vulnerable? The first thing is to determine the protection needs of data in transit and at rest. For example, passwords, credit card numbers, health records, personal information and business secrets require extra protection, particularly if that data falls under privacy laws, e.g. EU's General Data Protection Regulation (GDPR), or regulations, e.g. financial data protection such as PCI Data Security Standard (PCI DSS). For all such data:

• Is any data transmitted in clear text? This concerns protocols such as HTTP, SMTP, and FTP. External internet traffic is especially dangerous. Verify all internal traffic e.g. between load balancers, web servers, or back-end systems.

• Is sensitive data stored in clear text, including backups?

• Are any old or weak cryptographic algorithms used either by default or in older code?

• Are default crypto keys in use, weak crypto keys generated or re-used, or is proper key management or rotation missing?

• Is encryption not enforced, e.g. are any user agent (browser) security directives or headers missing?

• Does the user agent (e.g. app, mail client) not verify if the received server certificate is valid?

See ASVS Crypto (V7), Data Prot (V9) and SSL/TLS (V10)

References OWASP • OWASP Proactive Controls: Protect Data

• OWASP Application Security Verification Standard (V7,9,10)

• OWASP Cheat Sheet: Transport Layer Protection

• OWASP Cheat Sheet: User Privacy Protection

• OWASP Cheat Sheets: Password and Cryptographic Storage

• OWASP Security Headers Project; Cheat Sheet: HSTS

• OWASP Testing Guide: Testing for weak cryptography

External • CWE-220: Exposure of sens. information through data queries

• CWE-310: Cryptographic Issues; CWE-311: Missing Encryption

• CWE-312: Cleartext Storage of Sensitive Information

• CWE-319: Cleartext Transmission of Sensitive Information

• CWE-326: Weak Encryption; CWE-327: Broken/Risky Crypto

• CWE-359: Exposure of Private Information (Privacy Violation)

How to Prevent Do the following, at a minimum, and consult the references:

• Classify data processed, stored, or transmitted by an application. Identify which data is sensitive according to privacy laws, regulatory requirements, or business needs.

• Apply controls as per the classification.

• Don’t store sensitive data unnecessarily. Discard it as soon as possible or use PCI DSS compliant tokenization or even truncation. Data that is not retained cannot be stolen.

• Make sure to encrypt all sensitive data at rest.

• Ensure up-to-date and strong standard algorithms, protocols, and keys are in place; use proper key management.

• Encrypt all data in transit with secure protocols such as TLS with perfect forward secrecy (PFS) ciphers, cipher prioritization by the server, and secure parameters. Enforce encryption using directives like HTTP Strict Transport Security (HSTS).

• Disable caching for responses that contain sensitive data.

• Store passwords using strong adaptive and salted hashing functions with a work factor (delay factor), such as Argon2, scrypt, bcrypt, or PBKDF2.

• Verify independently the effectiveness of configuration and settings.

A3 :2017

Sensitive Data Exposure

Exploitability: 2 Prevalence: 3 Detectability: 2 Technical: 3

Rather than directly attacking crypto, attackers steal keys, execute man-in- the-middle attacks, or steal clear text data off the server, while in transit, or from the user’s client, e.g. browser. A manual attack is generally required. Previously retrieved password databases could be brute forced by Graphics Processing Units (GPUs).

Over the last few years, this has been the most common impactful attack. The most common flaw is simply not encrypting sensitive data. When crypto is employed, weak key generation and management, and weak algorithm, protocol and cipher usage is common, particularly for weak password hashing storage techniques. For data in transit, server side weaknesses are mainly easy to detect, but hard for data at rest.

Failure frequently compromises all data that should have been protected. Typically, this information includes sensitive personal information (PII) data such as health records, creden- tials, personal data, and credit cards, which often require protection as defined by laws or regulations such as the EU GDPR or local privacy laws.

https://www.owasp.org/index.php/ASVS_V7_Cryptography
https://www.owasp.org/index.php/ASVS_V9_Data_Protection
https://www.owasp.org/index.php/ASVS_V10_Communications
https://www.owasp.org/index.php/OWASP_Proactive_Controls#7:_Protect_Data
https://www.owasp.org/index.php/ASVS_V7_Cryptography
https://www.owasp.org/index.php/ASVS_V9_Data_Protection
https://www.owasp.org/index.php/ASVS_V10_Communications
https://www.owasp.org/index.php/Transport_Layer_Protection_Cheat_Sheet
https://www.owasp.org/index.php/User_Privacy_Protection_Cheat_Sheet
https://www.owasp.org/index.php/Transport_Layer_Protection_Cheat_Sheet
https://www.owasp.org/index.php/User_Privacy_Protection_Cheat_Sheet
https://www.owasp.org/index.php/Password_Storage_Cheat_Sheet
https://www.owasp.org/index.php/Cryptographic_Storage_Cheat_Sheet
https://www.owasp.org/index.php/OWASP_Secure_Headers_Project
https://www.owasp.org/index.php/HTTP_Strict_Transport_Security_Cheat_Sheet
https://www.owasp.org/index.php/Testing_for_weak_Cryptography
http://cwe.mitre.org/data/definitions/310.html
http://cwe.mitre.org/data/definitions/310.html
http://cwe.mitre.org/data/definitions/311.html
http://cwe.mitre.org/data/definitions/312.html
http://cwe.mitre.org/data/definitions/319.html
http://cwe.mitre.org/data/definitions/326.html
http://cwe.mitre.org/data/definitions/326.html
https://cwe.mitre.org/data/definitions/359.html
https://www.owasp.org/index.php/HTTP_Strict_Transport_Security_Cheat_Sheet
https://www.cryptolux.org/index.php/Argon2
https://wikipedia.org/wiki/Scrypt
https://wikipedia.org/wiki/Bcrypt
https://wikipedia.org/wiki/PBKDF2
App. Specific Business ?

10

Impacts Threat

Agents Attack

Vectors

Security

Weakness

Example Attack Scenarios Numerous public XXE issues have been discovered, including

attacking embedded devices. XXE occurs in a lot of unexpected

places, including deeply nested dependencies. The easiest way

is to upload a malicious XML file, if accepted:

Scenario #1: The attacker attempts to extract data from the server:

]>

&xxe;

Scenario #2: An attacker probes the server's private network by changing the above ENTITY line to:

]>

Scenario #3: An attacker attempts a denial-of-service attack by including a potentially endless file:

]>

Is the Application Vulnerable? Applications and in particular XML-based web services or downstream integrations might be vulnerable to attack if:

• The application accepts XML directly or XML uploads, especially from untrusted sources, or inserts untrusted data into XML documents, which is then parsed by an XML processor.

• Any of the XML processors in the application or SOAP based web services has document type definitions (DTDs) enabled. As the exact mechanism for disabling DTD processing varies by processor, it is good practice to consult a reference such as the OWASP Cheat Sheet 'XXE Prevention’.

• If your application uses SAML for identity processing within

federated security or single sign on (SSO) purposes. SAML

uses XML for identity assertions, and may be vulnerable.

• If the application uses SOAP prior to version 1.2, it is likely

susceptible to XXE attacks if XML entities are being passed to

the SOAP framework.

• Being vulnerable to XXE attacks likely means that the application is vulnerable to denial of service attacks including the Billion Laughs attack.

References OWASP • OWASP Application Security Verification Standard

• OWASP Testing Guide: Testing for XML Injection

• OWASP XXE Vulnerability

• OWASP Cheat Sheet: XXE Prevention

• OWASP Cheat Sheet: XML Security

External • CWE-611: Improper Restriction of XXE

• Billion Laughs Attack

• SAML Security XML External Entity Attack

• Detecting and exploiting XXE in SAML Interfaces

How to Prevent Developer training is essential to identify and mitigate XXE.

Besides that, preventing XXE requires:

• Whenever possible, use less complex data formats such as JSON, and avoiding serialization of sensitive data.

• Patch or upgrade all XML processors and libraries in use by the application or on the underlying operating system. Use dependency checkers. Update SOAP to SOAP 1.2 or higher.

• Disable XML external entity and DTD processing in all XML parsers in the application, as per the OWASP Cheat Sheet 'XXE Prevention'.

• Implement positive ("whitelisting") server-side input validation, filtering, or sanitization to prevent hostile data within XML documents, headers, or nodes.

• Verify that XML or XSL file upload functionality validates incoming XML using XSD validation or similar.

• SAST tools can help detect XXE in source code, although manual code review is the best alternative in large, complex applications with many integrations.

If these controls are not possible, consider using virtual patching, API security gateways, or Web Application Firewalls (WAFs) to detect, monitor, and block XXE attacks.

A4 :2017

XML External Entities (XXE)

Exploitability: 2 Prevalence: 2 Detectability: 3 Technical: 3

Attackers can exploit vulnerable XML processors if they can upload XML or include hostile content in an XML document, exploiting vulnerable code, dependencies or integrations.

By default, many older XML processors allow specification of an external entity, a URI that is dereferenced and evaluated during XML processing.

SAST tools can discover this issue by inspecting dependencies and configuration. DAST tools require additional manual steps to detect and exploit this issue. Manual testers need to be trained in how to test for XXE, as it not commonly tested as of 2017.

These flaws can be used to extract data, execute a remote request from the server, scan internal systems, perform a denial-of-service attack, as well as execute other attacks.

The business impact depends on the protection needs of all affected application and data.

https://www.w3schools.com/xml/xml_dtd_intro.asp
https://www.owasp.org/index.php/XML_External_Entity_(XXE)_Prevention_Cheat_Sheet
https://www.owasp.org/index.php/Category:OWASP_Application_Security_Verification_Standard_Project#tab=Home
https://www.owasp.org/index.php/Testing_for_XML_Injection_(OTG-INPVAL-008)
https://www.owasp.org/index.php/XML_External_Entity_(XXE)_Processing
https://www.owasp.org/index.php/XML_External_Entity_(XXE)_Prevention_Cheat_Sheet
https://www.owasp.org/index.php/XML_Security_Cheat_Sheet
https://cwe.mitre.org/data/definitions/611.html
http://blog.ioactive.com/2014/11/die-laughing-from-billion-laughs.html
https://secretsofappsecurity.blogspot.tw/2017/01/saml-security-xml-external-entity-attack.html
https://web-in-security.blogspot.tw/2014/11/detecting-and-exploiting-xxe-in-saml.html
https://www.owasp.org/index.php/XML_External_Entity_(XXE)_Prevention_Cheat_Sheet
https://www.owasp.org/index.php/Source_Code_Analysis_Tools
https://www.owasp.org/index.php/Source_Code_Analysis_Tools
https://www.owasp.org/index.php/Category:Vulnerability_Scanning_Tools
App. Specific Business ?

11

Impacts Threat

Agents Attack

Vectors

Security

Weakness

Example Attack Scenarios Scenario #1: The application uses unverified data in a SQL call that is accessing account information:

pstmt.setString(1, request.getParameter("acct"));

ResultSet results = pstmt.executeQuery( );

An attacker simply modifies the 'acct' parameter in the browser to send whatever account number they want. If not properly verified, the attacker can access any user's account.

http://example.com/app/accountInfo?acct=notmyacct

Scenario #2: An attacker simply force browses to target URLs. Admin rights are required for access to the admin page.

http://example.com/app/getappInfo

http://example.com/app/admin_getappInfo

If an unauthenticated user can access either page, it’s a flaw. If a non-admin can access the admin page, this is a flaw.

Is the Application Vulnerable? Access control enforces policy such that users cannot act

outside of their intended permissions. Failures typically lead to

unauthorized information disclosure, modification or destruction

of all data, or performing a business function outside of the limits

of the user. Common access control vulnerabilities include:

• Bypassing access control checks by modifying the URL,

internal application state, or the HTML page, or simply using a

custom API attack tool.

• Allowing the primary key to be changed to another users

record, permitting viewing or editing someone else's account.

• Elevation of privilege. Acting as a user without being logged in,

or acting as an admin when logged in as a user.

• Metadata manipulation, such as replaying or tampering with a

JSON Web Token (JWT) access control token or a cookie or

hidden field manipulated to elevate privileges, or abusing JWT

invalidation

• CORS misconfiguration allows unauthorized API access.

• Force browsing to authenticated pages as an unauthenticated

user or to privileged pages as a standard user. Accessing API

with missing access controls for POST, PUT and DELETE.

References OWASP • OWASP Proactive Controls: Access Controls

• OWASP Application Security Verification Standard: V4 Access Control

• OWASP Testing Guide: Authorization Testing

• OWASP Cheat Sheet: Access Control