CWE-294: Authentication Bypass by Capture-replay

What is CWE-294?

CWE-294 is Authentication Bypass by Capture-replay. The flaw arises when a capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes). The database currently holds 77 vulnerabilities mapped to CWE-294 and none of them are in the CISA Known Exploited Vulnerabilities catalog.

Analyzing data...

OWASP TOP 10:2025 RANK7 — A07:2025 — Authentication Failures
Related CVES (365 days)77
AbstractionBase
Likelihood of exploitHigh

Vulnerabilities mapped to CWE-294

77 vulnerabilities863% increase year over year

No data

No vulnerability data in CISA KEV for CWE-294

Official definition

ByMitre CWE

A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes).

Capture-replay attacks are common and can be difficult to defeat without cryptography. They are a subset of network injection attacks that rely on observing previously-sent valid commands, then changing them slightly if necessary and resending the same commands to the server.

Characteristics

Modes of introduction

  • Architecture and Design: COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.

Common consequences

ImpactScopeExplanation
Gain Privileges or Assume IdentityAccess ControlMessages sent with a capture-relay attack allow access to resources which are not otherwise accessible without proper authentication.

Risk mitigations

  1. Architecture and DesignUtilize some sequence or time stamping functionality along with a checksum which takes this into account in order to ensure that messages can be parsed only once.
  2. Architecture and DesignSince any attacker who can listen to traffic can see sequence numbers, it is necessary to sign messages with some kind of cryptography to ensure that sequence numbers are not simply doctored along with content.

Representative vulnerabilities

Sources (2)

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