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ID

CWE-342: Predictable Exact Value from Previous Values

Weakness ID: 342
Abstraction: Base
Status: Draft
Presentation Filter:
+ Description

Description Summary

An exact value or random number can be precisely predicted by observing previous values.
+ Time of Introduction
  • Architecture and Design
  • Implementation
+ Applicable Platforms

Languages

All

+ Common Consequences
ScopeEffect
Other

Technical Impact: Varies by context

+ Observed Examples
ReferenceDescription
Firewall generates easily predictable initial sequence numbers (ISN), which allows remote attackers to spoof connections.
Listening TCP ports are sequentially allocated, allowing spoofing attacks.
Predictable TCP sequence numbers allow spoofing.
DNS resolver uses predictable IDs, allowing a local user to spoof DNS query results.
+ Potential Mitigations

Increase the entropy used to seed a PRNG.

Phases: Architecture and Design; Requirements

Strategy: Libraries or Frameworks

Use products or modules that conform to FIPS 140-2 [R.342.1] to avoid obvious entropy problems. Consult FIPS 140-2 Annex C ("Approved Random Number Generators").

Phase: Implementation

Use a PRNG that periodically re-seeds itself using input from high-quality sources, such as hardware devices with high entropy. However, do not re-seed too frequently, or else the entropy source might block.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness ClassWeakness Class330Use of Insufficiently Random Values
Development Concepts (primary)699
Research Concepts (primary)1000
ChildOfCategoryCategory905SFP Primary Cluster: Predictability
Software Fault Pattern (SFP) Clusters (primary)888
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERPredictable Exact Value from Previous Values
+ References
[R.342.1] [REF-1] Information Technology Laboratory, National Institute of Standards and Technology. "SECURITY REQUIREMENTS FOR CRYPTOGRAPHIC MODULES". 2001-05-25. <http://csrc.nist.gov/publications/fips/fips140-2/fips1402.pdf>.
[R.342.2] [REF-17] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 20: Weak Random Numbers." Page 299. McGraw-Hill. 2010.
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
PLOVERExternally Mined
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Time_of_Introduction
2008-09-08CWE Content TeamMITREInternal
updated Relationships, Taxonomy_Mappings
2009-03-10CWE Content TeamMITREInternal
updated Potential_Mitigations
2009-12-28CWE Content TeamMITREInternal
updated Potential_Mitigations
2010-06-21CWE Content TeamMITREInternal
updated Potential_Mitigations
2011-06-01CWE Content TeamMITREInternal
updated Common_Consequences
2011-06-27CWE Content TeamMITREInternal
updated Common_Consequences
2011-09-13CWE Content TeamMITREInternal
updated Potential_Mitigations, References
2012-05-11CWE Content TeamMITREInternal
updated Observed_Examples, References, Relationships
2012-10-30CWE Content TeamMITREInternal
updated Potential_Mitigations

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Page Last Updated: May 05, 2017