Authentication Bypass by Alternate Name
Weakness ID: 289 (Weakness Variant)Status: Incomplete
+ Description

Description Summary

The software performs authentication based on the name of a resource being accessed, or the name of the actor performing the access, but it does not properly check all possible names for that resource or actor.
+ Time of Introduction
  • Architecture and Design
  • Implementation
+ Applicable Platforms



+ Observed Examples
CVE-2003-0317Protection mechanism that restricts URL access can be bypassed using URL encoding.
CVE-2004-0847Bypass of authentication for files using "\" (backslash) or "%5C" (encoded backslash).
+ Potential Mitigations

Phase: Architecture and Design

Avoid making decisions based on names of resources (e.g. files) if those resources can have alternate names.

Phase: Architecture and Design

Assume all input is malicious. Use a standard input validation mechanism to validate all input for length, type, syntax, and business rules before accepting the data to be displayed or stored. Use an "accept known good" validation strategy. Input (specifically, unexpected CRLFs) that is not appropriate should not be processed into HTTP headers.

Phase: Architecture and Design

Use and specify a strong output encoding (such as ISO 8859-1 or UTF 8).

Do not rely exclusively on blacklist validation to detect malicious input or to encode output. There are too many variants to encode a character, so you're likely to miss some variants.

Inputs should be decoded and canonicalized to the application's current internal representation before being validated. Make sure that your application does not decode the same input twice. Such errors could be used to bypass whitelist schemes by introducing dangerous inputs after they have been checked.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness ClassWeakness Class592Authentication Bypass Issues
Development Concepts (primary)699
Research Concepts (primary)1000
CanFollowWeakness VariantWeakness Variant46Path Equivalence: 'filename ' (Trailing Space)
Research Concepts1000
CanFollowWeakness VariantWeakness Variant52Path Equivalence: '/multiple/trailing/slash//'
Research Concepts1000
CanFollowCategoryCategory171Cleansing, Canonicalization, and Comparison Errors
Research Concepts1000
CanFollowWeakness VariantWeakness Variant173Failure to Handle Alternate Encoding
Research Concepts1000
CanFollowWeakness BaseWeakness Base178Failure to Resolve Case Sensitivity
Research Concepts1000
+ Relationship Notes

Overlaps equivalent encodings, canonicalization, authorization, multiple trailing slash, trailing space, mixed case, and other equivalence issues.

+ Theoretical Notes

Alternate names are useful in data driven manipulation attacks, not just for authentication.

+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERAuthentication bypass by alternate name
+ Content History
Submission DateSubmitterOrganizationSource
PLOVERExternally Mined
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Potential Mitigations, Time of Introduction
2008-09-08CWE Content TeamMITREInternal
updated Description, Relationships, Other Notes, Relationship Notes, Taxonomy Mappings
2008-11-24CWE Content TeamMITREInternal
updated Observed Examples
2009-07-27CWE Content TeamMITREInternal
updated Other Notes, Potential Mitigations, Theoretical Notes