Predictable Exact Value from Previous Values
Weakness ID: 342 (Weakness Base)Status: Draft
+ 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



+ Observed Examples
CVE-1999-0074Listening TCP ports are sequentially allocated, allowing spoofing attacks.
CVE-1999-0077Predictable TCP sequence numbers allow spoofing.
CVE-2000-0335DNS resolver uses predictable IDs, allowing a local user to spoof DNS query results.
+ Potential Mitigations

Increase the entropy used to seed a PRNG.

Phase: Implementation

Perform FIPS 140-2 tests on data to catch obvious entropy problems.

Phase: Implementation

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

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness ClassWeakness Class330Use of Insufficiently Random Values
Development Concepts (primary)699
Research Concepts (primary)1000
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERPredictable Exact Value from Previous Values
+ Content History
Submission DateSubmitterOrganizationSource
PLOVERExternally Mined
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