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Common Weakness Enumeration

A community-developed list of SW & HW weaknesses that can become vulnerabilities

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ID

CWE-332: Insufficient Entropy in PRNG

Weakness ID: 332
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: VariantVariant - a weakness that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
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+ Description
The lack of entropy available for, or used by, a Pseudo-Random Number Generator (PRNG) can be a stability and security threat.
+ Common Consequences
Section HelpThis table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
ScopeImpactLikelihood
Availability

Technical Impact: DoS: Crash, Exit, or Restart

If a pseudo-random number generator is using a limited entropy source which runs out (if the generator fails closed), the program may pause or crash.
Access Control
Other

Technical Impact: Bypass Protection Mechanism; Other

If a PRNG is using a limited entropy source which runs out, and the generator fails open, the generator could produce predictable random numbers. Potentially a weak source of random numbers could weaken the encryption method used for authentication of users.
+ Potential Mitigations

Phases: Architecture and Design; Requirements

Strategy: Libraries or Frameworks

Use products or modules that conform to FIPS 140-2 [REF-267] to avoid obvious entropy problems. Consult FIPS 140-2 Annex C ("Approved Random Number Generators").

Phase: Implementation

Consider a PRNG that re-seeds itself as needed from high-quality pseudo-random output, such as hardware devices.

Phase: Architecture and Design

When deciding which PRNG to use, look at its sources of entropy. Depending on what your security needs are, you may need to use a random number generator that always uses strong random data -- i.e., a random number generator that attempts to be strong but will fail in a weak way or will always provide some middle ground of protection through techniques like re-seeding. Generally, something that always provides a predictable amount of strength is preferable.
+ Relationships
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Research Concepts" (CWE-1000)
NatureTypeIDName
ChildOfBaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.331Insufficient Entropy
Section HelpThis table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
+ Relevant to the view "Architectural Concepts" (CWE-1008)
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1013Encrypt Data
+ Modes Of Introduction
Section HelpThe different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
PhaseNote
Architecture and Design
ImplementationREALIZATION: This weakness is caused during implementation of an architectural security tactic.
+ Applicable Platforms
Section HelpThis listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.

Languages

Class: Not Language-Specific (Undetermined Prevalence)

+ Likelihood Of Exploit
Medium
+ Observed Examples
ReferenceDescription
Chain: JavaScript-based cryptocurrency library can fall back to the insecure Math.random() function instead of reporting a failure (CWE-392), thus reducing the entropy (CWE-332) and leading to generation of non-unique cryptographic keys for Bitcoin wallets (CWE-1391)
security product has insufficient entropy in the DRBG, allowing collisions and private key discovery
+ Memberships
Section HelpThis MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.861The CERT Oracle Secure Coding Standard for Java (2011) Chapter 18 - Miscellaneous (MSC)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.905SFP Primary Cluster: Predictability
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1152SEI CERT Oracle Secure Coding Standard for Java - Guidelines 49. Miscellaneous (MSC)
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1414Comprehensive Categorization: Randomness
+ Vulnerability Mapping Notes

Usage: ALLOWED

(this CWE ID could be used to map to real-world vulnerabilities)

Reason: Acceptable-Use

Rationale:

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.

Comments:

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.
+ Notes

Maintenance

As of CWE 4.5, terminology related to randomness, entropy, and predictability can vary widely. Within the developer and other communities, "randomness" is used heavily. However, within cryptography, "entropy" is distinct, typically implied as a measurement. There are no commonly-used definitions, even within standards documents and cryptography papers. Future versions of CWE will attempt to define these terms and, if necessary, distinguish between them in ways that are appropriate for different communities but do not reduce the usability of CWE for mapping, understanding, or other scenarios.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
CLASPInsufficient entropy in PRNG
The CERT Oracle Secure Coding Standard for Java (2011)MSC02-JGenerate strong random numbers
+ References
[REF-267] Information Technology Laboratory, National Institute of Standards and Technology. "SECURITY REQUIREMENTS FOR CRYPTOGRAPHIC MODULES". 2001-05-25. <https://csrc.nist.gov/csrc/media/publications/fips/140/2/final/documents/fips1402.pdf>. URL validated: 2023-04-07.
[REF-18] Secure Software, Inc.. "The CLASP Application Security Process". 2005. <https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>.
[REF-1374] Unciphered. "Randstorm: You Can't Patch a House of Cards". 2023-11-14. <https://www.unciphered.com/blog/randstorm-you-cant-patch-a-house-of-cards>. URL validated: 2023-11-15.
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
CLASP
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2009-03-10CWE Content TeamMITRE
updated Potential_Mitigations
2009-12-28CWE Content TeamMITRE
updated Potential_Mitigations
2010-06-21CWE Content TeamMITRE
updated Potential_Mitigations
2011-06-01CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Relationships, Taxonomy_Mappings
2011-09-13CWE Content TeamMITRE
updated Potential_Mitigations, References
2012-05-11CWE Content TeamMITRE
updated Common_Consequences, Demonstrative_Examples, Relationships
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Modes_of_Introduction, References, Relationships
2019-01-03CWE Content TeamMITRE
updated Relationships, Taxonomy_Mappings
2019-06-20CWE Content TeamMITRE
updated Relationships
2020-02-24CWE Content TeamMITRE
updated Relationships
2021-03-15CWE Content TeamMITRE
updated References
2021-07-20CWE Content TeamMITRE
updated Maintenance_Notes
2021-10-28CWE Content TeamMITRE
updated Observed_Examples
2023-04-27CWE Content TeamMITRE
updated References, Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
2024-02-29
(CWE 4.14, 2024-02-29)
CWE Content TeamMITRE
updated Observed_Examples, References
Page Last Updated: July 16, 2024