Improper Handling of Unexpected Data Type
Weakness ID: 241 (Weakness Base)Status: Draft
+ Description

Description Summary

The software does not handle or incorrectly handles when a particular element is not the expected type, e.g. it expects a digit (0-9) but is provided with a letter (A-Z).
+ Time of Introduction
  • Architecture and Design
  • Implementation
+ Applicable Platforms

Languages

All

+ Observed Examples
ReferenceDescription
CVE-1999-1156FTP server crash via PORT command with non-numeric character.
CVE-2004-0270Anti-virus product has assert error when line length is non-numeric.
+ Potential Mitigations

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.

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 Class228Improper Handling of Syntactically Invalid Structure
Development Concepts (primary)699
Research Concepts (primary)1000
ChildOfCategoryCategory743CERT C Secure Coding Section 09 - Input Output (FIO)
Weaknesses Addressed by the CERT C Secure Coding Standard (primary)734
+ Research Gaps

Probably under-studied.

+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERWrong Data Type
CERT C Secure CodingFIO37-CDo not assume character data has been read
+ Related Attack Patterns
CAPEC-IDAttack Pattern Name
(CAPEC Version: 1.4)
48Passing Local Filenames to Functions That Expect a URL
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVERExternally Mined
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Potential Mitigations, Time of Introduction
2008-09-08CWE Content TeamMITREInternal
updated Relationships, Taxonomy Mappings
2008-11-24CWE Content TeamMITREInternal
updated Relationships, Taxonomy Mappings
2009-03-10CWE Content TeamMITREInternal
updated Description, Name
2009-07-27CWE Content TeamMITREInternal
updated Potential Mitigations
2009-10-29CWE Content TeamMITREInternal
updated Description
Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Wrong Data Type
2009-03-10Failure to Handle Wrong Data Type