cwe.mitre.org Open in urlscan Pro
192.52.194.135  Public Scan

Form analysis
1 forms found in the DOM

/cgi-bin/jumpmenu.cgi

<form action="/cgi-bin/jumpmenu.cgi" align="right" style="padding:0px; margin:0px"> ID <label for="id" style="padding-right:5px">Lookup:</label>
  <input id="id" name="id" type="text" style="width:50px; font-size:80%" maxlength="10">
  <input value="Go" style="padding: 0px; font-size:80%" type="submit">
</form>

Text Content

COMMON WEAKNESS ENUMERATION

A Community-Developed List of Software & Hardware Weakness Types



Home > CWE List > CWE- Individual Dictionary Definition (4.7)  
ID Lookup:

--------------------------------------------------------------------------------

 * Home
 * About
   Overview Board Board Meeting Minutes History Documents FAQs Glossary
 * CWE List
   Latest Version Downloads Reports Visualizations Archive
 * Scoring
   Methodologies Prioritizing Weaknesses CWSS CWRAF Top 25 Top Hardware
 * Mapping Guidance
   CVE → CWE Mapping Guidance CVE → CWE Mapping Quick Tips CVE → CWE Mapping
   Examples Common Terms Cheatsheet
 * Community
   Community Members Working Groups & Special Interest Groups Compatibility
   Discussion List Discussion Archives Content Suggestions
 * News
   Current News Twitter LinkedIn YouTube Podcast Medium News Archive
 * Search

CWE Glossary Definition



CWE-331: INSUFFICIENT ENTROPY


Weakness ID: 331
Abstraction: Base
Structure: Simple

Presentation Filter:
Basic Complete High Level Mapping-Friendly
Description
The software uses an algorithm or scheme that produces insufficient entropy,
leaving patterns or clusters of values that are more likely to occur than
others.
Relationships
This 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)

NatureTypeIDNameChildOfClass - a weakness that is described in a very abstract
fashion, typically independent of any specific language or technology. More
specific than a Pillar Weakness, but more general than a Base Weakness. Class
level weaknesses typically describe issues in terms of 1 or 2 of the following
dimensions: behavior, property, and resource.330Use of Insufficiently Random
ValuesParentOfVariant - 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.332Insufficient Entropy in PRNGParentOfVariant - 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.333Improper Handling of
Insufficient Entropy in TRNG

This 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 "Software Development" (CWE-699)

NatureTypeIDNameMemberOfCategory - a CWE entry that contains a set of other
entries that share a common characteristic.1213Random Number
IssuesMemberOfCategory - a CWE entry that contains a set of other entries that
share a common characteristic.310Cryptographic Issues

This 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 "Weaknesses for Simplified Mapping of Published
Vulnerabilities" (CWE-1003)

NatureTypeIDNameChildOfClass - a weakness that is described in a very abstract
fashion, typically independent of any specific language or technology. More
specific than a Pillar Weakness, but more general than a Base Weakness. Class
level weaknesses typically describe issues in terms of 1 or 2 of the following
dimensions: behavior, property, and resource.330Use of Insufficiently Random
Values

This 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)

NatureTypeIDNameMemberOfCategory - a CWE entry that contains a set of other
entries that share a common characteristic.1013Encrypt Data

Modes Of Introduction
The 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.

PhaseNoteArchitecture and DesignImplementationREALIZATION: This weakness is
caused during implementation of an architectural security tactic.

Applicable Platforms
This 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: Language-Independent (Undetermined Prevalence)

Common Consequences
This 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.

ScopeImpactLikelihoodAccess Control
Other


Technical Impact: Bypass Protection Mechanism; Other

An attacker could guess the random numbers generated and could gain unauthorized
access to a system if the random numbers are used for authentication and
authorization.

Demonstrative Examples

Example 1

This code generates a unique random identifier for a user's session.

(bad code)
Example Language: PHP 
function generateSessionID($userID){
srand($userID);
return rand();
}

Because the seed for the PRNG is always the user's ID, the session ID will
always be the same. An attacker could thus predict any user's session ID and
potentially hijack the session.

This example also exhibits a Small Seed Space (CWE-339).

Example 2

The following code uses a statistical PRNG to create a URL for a receipt that
remains active for some period of time after a purchase.

(bad code)
Example Language: Java 
String GenerateReceiptURL(String baseUrl) {
Random ranGen = new Random();
ranGen.setSeed((new Date()).getTime());
return(baseUrl + ranGen.nextInt(400000000) + ".html");
}

This code uses the Random.nextInt() function to generate "unique" identifiers
for the receipt pages it generates. Because Random.nextInt() is a statistical
PRNG, it is easy for an attacker to guess the strings it generates. Although the
underlying design of the receipt system is also faulty, it would be more secure
if it used a random number generator that did not produce predictable receipt
identifiers, such as a cryptographic PRNG.

Observed Examples

ReferenceDescription
CVE-2001-0950
Insufficiently random data used to generate session tokens using C rand(). Also,
for certificate/key generation, uses a source that does not block when entropy
is low.
CVE-2008-2108
Chain: insufficient precision (CWE-1339) in random-number generator causes some
zero bits to be reliably generated, reducing the amount of entropy (CWE-331)

Potential Mitigations

Phase: Implementation

Determine the necessary entropy to adequately provide for randomness and
predictability. This can be achieved by increasing the number of bits of objects
such as keys and seeds.

Memberships
This 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.

NatureTypeIDNameMemberOfView - a subset of CWE entries that provides a way of
examining CWE content. The two main view structures are Slices (flat lists) and
Graphs (containing relationships between entries).884CWE
Cross-sectionMemberOfCategory - a CWE entry that contains a set of other entries
that share a common characteristic.905SFP Primary Cluster:
PredictabilityMemberOfCategory - a CWE entry that contains a set of other
entries that share a common characteristic.1170SEI CERT C Coding Standard -
Guidelines 48. Miscellaneous (MSC)MemberOfCategory - a CWE entry that contains a
set of other entries that share a common characteristic.1346OWASP Top Ten 2021
Category A02:2021 - Cryptographic Failures

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 PLOVERInsufficient Entropy
WASC11Brute Force CERT C Secure CodingMSC32-CExactProperly seed pseudorandom
number generators

Related Attack Patterns

CAPEC-IDAttack Pattern Name CAPEC-59Session Credential Falsification through
Prediction

References
[REF-207] John Viega and Gary McGraw. "Building Secure Software: How to Avoid
Security Problems the Right Way". 1st Edition. Addison-Wesley. 2002.

Content History

SubmissionsSubmission DateSubmitterOrganization2006-07-19PLOVER
ModificationsModification DateModifierOrganization2008-07-01Eric
DalciCigitalupdated Time_of_Introduction2008-09-08CWE Content TeamMITREupdated
Relationships, Taxonomy_Mappings2010-02-16CWE Content TeamMITREupdated
Taxonomy_Mappings2011-06-01CWE Content TeamMITREupdated
Common_Consequences2012-05-11CWE Content TeamMITREupdated Common_Consequences,
Demonstrative_Examples, References, Relationships2012-10-30CWE Content
TeamMITREupdated Potential_Mitigations2015-12-07CWE Content TeamMITREupdated
Relationships2017-11-08CWE Content TeamMITREupdated Applicable_Platforms,
Modes_of_Introduction, Relationships, Taxonomy_Mappings2019-01-03CWE Content
TeamMITREupdated Relationships2019-06-20CWE Content TeamMITREupdated
Relationships2020-02-24CWE Content TeamMITREupdated Relationships2021-07-20CWE
Content TeamMITREupdated Maintenance_Notes, Observed_Examples2021-10-28CWE
Content TeamMITREupdated Relationships

More information is available — Please select a different filter.

Page Last Updated: April 28, 2022
 

Site Map | Terms of Use | Privacy Policy | Contact Us |

Use of the Common Weakness Enumeration (CWE) and the associated references from
this website are subject to the Terms of Use. CWE is sponsored by the U.S.
Department of Homeland Security (DHS) Cybersecurity and Infrastructure Security
Agency (CISA) and managed by the Homeland Security Systems Engineering and
Development Institute (HSSEDI) which is operated by The MITRE Corporation
(MITRE). Copyright © 2006–2022, The MITRE Corporation. CWE, CWSS, CWRAF, and the
CWE logo are trademarks of The MITRE Corporation.