CWE - CWE-323: Reusing a Nonce, Key Pair in Encryption (4.18)

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CWE Glossary Definition

CWE-323: Reusing a Nonce, Key Pair in Encryption

Weakness ID: 323

Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction: Base Base - 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.

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Description

Nonces should be used for the present occasion and only once.

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.

Impact	Details
Bypass Protection Mechanism; Gain Privileges or Assume Identity	Scope: Access Control Potentially a replay attack, in which an attacker could send the same data twice, could be crafted if nonces are allowed to be reused. This could allow a user to send a message which masquerades as a valid message from a valid user.

Potential Mitigations

Phase(s)	Mitigation
Implementation	Refuse to reuse nonce values.
Implementation	Use techniques such as requiring incrementing, time based and/or challenge response to assure uniqueness of nonces.

Relationships

Section Help 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" (View-1000)

Nature	Type	ID	Name
ChildOf	Base Base - 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.	344	Use of Invariant Value in Dynamically Changing Context

Relevant to the view "Software Development" (View-699)

Nature	Type	ID	Name
MemberOf	Category Category - a CWE entry that contains a set of other entries that share a common characteristic.	320	Key Management Errors

Relevant to the view "Architectural Concepts" (View-1008)

Nature	Type	ID	Name
MemberOf	Category Category - a CWE entry that contains a set of other entries that share a common characteristic.	1013	Encrypt Data

Background Details

Nonces are often bundled with a key in a communication exchange to produce a new session key for each exchange.

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.

Phase	Note
Architecture and Design	REALIZATION: 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

High

Demonstrative Examples

Example 1

This code takes a password, concatenates it with a nonce, then encrypts it before sending over a network:

(bad code)

Example Language: C

void encryptAndSendPassword(char *password){

char *nonce = "bad";
...
char *data = (unsigned char*)malloc(20);
int para_size = strlen(nonce) + strlen(password);
char *paragraph = (char*)malloc(para_size);
SHA1((const unsigned char*)paragraph,parsize,(unsigned char*)data);
sendEncryptedData(data)

}

Because the nonce used is always the same, an attacker can impersonate a trusted party by intercepting and resending the encrypted password. This attack avoids the need to learn the unencrypted password.

Example 2

This code sends a command to a remote server, using an encrypted password and nonce to prove the command is from a trusted party:

(bad code)

Example Language: C++

String command = new String("some command to execute");
MessageDigest nonce = MessageDigest.getInstance("SHA");
nonce.update(String.valueOf("bad nonce"));
byte[] nonce = nonce.digest();
MessageDigest password = MessageDigest.getInstance("SHA");
password.update(nonce + "secretPassword");
byte[] digest = password.digest();
sendCommand(digest, command)

Once again the nonce used is always the same. An attacker may be able to replay previous legitimate commands or execute new arbitrary commands.

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.

Nature	Type	ID	Name
MemberOf	ViewView - 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).	884	CWE Cross-section
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	959	SFP Secondary Cluster: Weak Cryptography
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	1346	OWASP Top Ten 2021 Category A02:2021 - Cryptographic Failures
MemberOf	CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.	1414	Comprehensive Categorization: Randomness

Vulnerability Mapping Notes

Usage ALLOWED

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

Reason Acceptable-Use

Rationale

This CWE entry is at the Base 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.

Taxonomy Mappings

Mapped Taxonomy Name	Node ID	Fit	Mapped Node Name
CLASP	Reusing a nonce, key pair in encryption

References

[REF-18] Secure Software, Inc.. "The CLASP Application Security Process". 2005.
<https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf>. (URL validated: 2024年11月17日)

Content History

Submissions
Submission Date	Submitter	Organization
2006年07月19日 (CWE Draft 3, 2006年07月19日)	CLASP
2006年07月19日 (CWE Draft 3, 2006年07月19日)
Modifications
Modification Date	Modifier	Organization
2023年06月29日	CWE Content Team	MITRE
2023年06月29日	updated Mapping_Notes
2023年04月27日	CWE Content Team	MITRE
2023年04月27日	updated Relationships, Type
2021年10月28日	CWE Content Team	MITRE
2021年10月28日	updated Relationships
2020年02月24日	CWE Content Team	MITRE
2020年02月24日	updated References
2019年06月20日	CWE Content Team	MITRE
2019年06月20日	updated Type
2017年11月08日	CWE Content Team	MITRE
2017年11月08日	updated Applicable_Platforms, Modes_of_Introduction, Relationships
2014年07月30日	CWE Content Team	MITRE
2014年07月30日	updated Relationships
2012年10月30日	CWE Content Team	MITRE
2012年10月30日	updated Demonstrative_Examples, Potential_Mitigations
2012年05月11日	CWE Content Team	MITRE
2012年05月11日	updated Relationships
2011年06月01日	CWE Content Team	MITRE
2011年06月01日	updated Common_Consequences
2008年09月08日	CWE Content Team	MITRE
2008年09月08日	updated Background_Details, Common_Consequences, Relationships, Taxonomy_Mappings
2008年07月01日	Eric Dalci	Cigital
2008年07月01日	updated Time_of_Introduction

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Page Last Updated: September 09, 2025

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