Failure to Handle Alternate Encoding
Weakness ID: 173 (Weakness Variant)Status: Draft
+ Description

Description Summary

The software does not properly handle when an input uses an alternate encoding that is valid for the control sphere to which the input is being sent.
+ Time of Introduction
  • Implementation
+ Applicable Platforms



+ Potential Mitigations

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.

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; 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 Class172Encoding Error
Development Concepts (primary)699
Research Concepts (primary)1000
CanPrecedeWeakness VariantWeakness Variant289Authentication Bypass by Alternate Name
Research Concepts1000
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERAlternate Encoding
+ Related Attack Patterns
CAPEC-IDAttack Pattern Name
(CAPEC Version: 1.4)
3Using Leading 'Ghost' Character Sequences to Bypass Input Filters
52Embedding NULL Bytes
53Postfix, Null Terminate, and Backslash
64Using Slashes and URL Encoding Combined to Bypass Validation Logic
72URL Encoding
78Using Escaped Slashes in Alternate Encoding
79Using Slashes in Alternate Encoding
71Using Unicode Encoding to Bypass Validation Logic
80Using UTF-8 Encoding to Bypass Validation Logic
+ Content History
Submission DateSubmitterOrganizationSource
PLOVERExternally Mined
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Potential Mitigations, Time of Introduction
2008-09-08CWE Content TeamMITREInternal
updated Relationships, Taxonomy Mappings
2009-07-27CWE Content TeamMITREInternal
updated Potential Mitigations
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Alternate Encoding