CWE-915 Detail

The product receives input from an upstream component that specifies multiple attributes, properties, or fields that are to be initialized or updated in an object, but it does not properly control which attributes can be modified.

If the object contains attributes that were only intended for internal use, then their unexpected modification could lead to a vulnerability.

This weakness is sometimes known by the language-specific mechanisms that make it possible, such as mass assignment, autobinding, or object injection.

Modes Of Introduction

Architecture and Design
Implementation

Applicable Platforms

Language

Name: Ruby (Undetermined)
Name: ASP.NET (Undetermined)
Name: PHP (Undetermined)
Name: Python (Undetermined)
Class: Not Language-Specific (Undetermined)

Common Consequences

Observed Examples

Potential Mitigations

Phases : Implementation

If available, use features of the language or framework that allow specification of allowlists of attributes or fields that are allowed to be modified. If possible, prefer allowlists over denylists.

For applications written with Ruby on Rails, use the attr_accessible (allowlist) or attr_protected (denylist) macros in each class that may be used in mass assignment.

Phases : Architecture and Design // Implementation
If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
Phases : Implementation
For any externally-influenced input, check the input against an allowlist of internal object attributes or fields that are allowed to be modified.
Phases : Implementation // Architecture and Design
Refactor the code so that object attributes or fields do not need to be dynamically identified, and only expose getter/setter functionality for the intended attributes.

Detection Methods

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)
Effectiveness : High

Vulnerability Mapping Notes

Justification : This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comment : Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.

NotesNotes

The relationships between CWE-502 and CWE-915 need further exploration. CWE-915 is more narrowly scoped to object modification, and is not necessarily used for deserialization.

References

REF-885

Shocking News in PHP Exploitation
Stefan Esser.
https://owasp.org/www-pdf-archive/POC2009-ShockingNewsInPHPExploitation.pdf

REF-886

"Two Security Vulnerabilities in the Spring Framework's MVC" pdf (from 2008)
Dinis Cruz.
http://diniscruz.blogspot.com/2011/07/two-security-vulnerabilities-in-spring.html

REF-887

Two Security Vulnerabilities in the Spring Framework's MVC
Ryan Berg, Dinis Cruz.
https://o2platform.files.wordpress.com/2011/07/ounce_springframework_vulnerabilities.pdf

REF-888

Best Practices for ASP.NET MVC
ASPNETUE.
https://web.archive.org/web/20100921074010/http://blogs.msdn.com/b/aspnetue/archive/2010/09/17/second_2d00_post.aspx

REF-889

Mass assignment in Rails applications
Michael Hartl.
https://web.archive.org/web/20090808163156/http://blog.mhartl.com/2008/09/21/mass-assignment-in-rails-applications/

REF-890

Secure your Rails apps!
Tobi.
https://pragtob.wordpress.com/2012/03/06/secure-your-rails-apps/

REF-891

Ruby On Rails Security Guide
Heiko Webers.
https://guides.rubyonrails.org/security.html#mass-assignment

REF-892

Mass Assignment Vulnerability in ASP.NET MVC
Josh Bush.
https://web.archive.org/web/20120309022539/http://freshbrewedcode.com/joshbush/2012/03/05/mass-assignment-aspnet-mvc

REF-893

6 Ways To Avoid Mass Assignment in ASP.NET MVC
K. Scott Allen.
https://odetocode.com/blogs/scott/archive/2012/03/11/complete-guide-to-mass-assignment-in-asp-net-mvc.aspx

REF-894

PHP Object Injection
Egidio Romano.
https://owasp.org/www-community/vulnerabilities/PHP_Object_Injection

REF-464

Unserializing user-supplied data, a bad idea
Heine Deelstra.
https://drupalsun.com/heine/2010/08/25/unserializing-user-supplied-data-bad-idea

REF-466

Why Python Pickle is Insecure
Nadia Alramli.
http://michael-rushanan.blogspot.com/2012/10/why-python-pickle-is-insecure.html

Submission

Modifications