Détail du CWE-196

CWE-196

Unsigned to Signed Conversion Error
Moyen
Draft
2006-07-19
00h00 +00:00
2023-06-29
00h00 +00:00
CWE Mitre.org
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Nom: Unsigned to Signed Conversion Error

The product uses an unsigned primitive and performs a cast to a signed primitive, which can produce an unexpected value if the value of the unsigned primitive can not be represented using a signed primitive.

Description du CWE

Although less frequent an issue than signed-to-unsigned conversion, unsigned-to-signed conversion can be the perfect precursor to dangerous buffer underwrite conditions that allow attackers to move down the stack where they otherwise might not have access in a normal buffer overflow condition. Buffer underwrites occur frequently when large unsigned values are cast to signed values, and then used as indexes into a buffer or for pointer arithmetic.

Informations générales

Modes d'introduction

Implementation

Plateformes applicables

Langue

Name: C (Undetermined)
Name: C++ (Undetermined)

Conséquences courantes

Portée Impact Probabilité
AvailabilityDoS: Crash, Exit, or Restart

Note: Incorrect sign conversions generally lead to undefined behavior, and therefore crashes.
IntegrityModify Memory

Note: If a poor cast lead to a buffer overflow or similar condition, data integrity may be affected.
Integrity
Confidentiality
Availability
Access Control		Execute Unauthorized Code or Commands, Bypass Protection Mechanism

Note: Improper signed-to-unsigned conversions without proper checking can sometimes trigger buffer overflows which can be used to execute arbitrary code. This is usually outside the scope of a program's implicit security policy.

Mesures d’atténuation potentielles

Phases : Requirements
Choose a language which is not subject to these casting flaws.
Phases : Architecture and Design
Design object accessor functions to implicitly check values for valid sizes. Ensure that all functions which will be used as a size are checked previous to use as a size. If the language permits, throw exceptions rather than using in-band errors.
Phases : Implementation
Error check the return values of all functions. Be aware of implicit casts made, and use unsigned variables for sizes if at all possible.

Notes de cartographie des vulnérabilités

Justification : This CWE entry is at the Variant level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Commentaire : 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.

Modèles d'attaque associés

CAPEC-ID Nom du modèle d'attaque
CAPEC-92 Forced Integer Overflow
This attack forces an integer variable to go out of range. The integer variable is often used as an offset such as size of memory allocation or similarly. The attacker would typically control the value of such variable and try to get it out of range. For instance the integer in question is incremented past the maximum possible value, it may wrap to become a very small, or negative number, therefore providing a very incorrect value which can lead to unexpected behavior. At worst the attacker can execute arbitrary code.

Références

REF-62

The Art of Software Security Assessment
Mark Dowd, John McDonald, Justin Schuh.

REF-18

The CLASP Application Security Process
Secure Software, Inc..
https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf

Soumission

Nom Organisation Date Date de publication Version
CLASP 2006-07-19 +00:00 2006-07-19 +00:00 Draft 3

Modifications

Nom Organisation Date Commentaire
CWE Content Team MITRE 2008-09-08 +00:00 updated Applicable_Platforms, Common_Consequences, Relationships, Other_Notes, Taxonomy_Mappings
CWE Content Team MITRE 2009-05-27 +00:00 updated Demonstrative_Examples
CWE Content Team MITRE 2009-10-29 +00:00 updated Common_Consequences
CWE Content Team MITRE 2010-12-13 +00:00 updated Other_Notes
CWE Content Team MITRE 2011-06-01 +00:00 updated Common_Consequences
CWE Content Team MITRE 2012-05-11 +00:00 updated References, Relationships
CWE Content Team MITRE 2012-10-30 +00:00 updated Potential_Mitigations
CWE Content Team MITRE 2014-06-23 +00:00 updated Demonstrative_Examples, Description, Other_Notes
CWE Content Team MITRE 2014-07-30 +00:00 updated Relationships, Taxonomy_Mappings
CWE Content Team MITRE 2020-02-24 +00:00 updated Relationships
CWE Content Team MITRE 2020-08-20 +00:00 updated Relationships
CWE Content Team MITRE 2020-12-10 +00:00 updated Relationships
CWE Content Team MITRE 2021-03-15 +00:00 updated References
CWE Content Team MITRE 2023-01-31 +00:00 updated Description
CWE Content Team MITRE 2023-04-27 +00:00 updated Relationships
CWE Content Team MITRE 2023-06-29 +00:00 updated Mapping_Notes