COMMON WEAKNESS ENUMERATIONIncomplete

CWE-294

Authentication Bypass by Capture-replay

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).

Abstraction

Base

Structure

Simple

Likelihood of Exploit

High

Understand the problem

What is the problem?

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).

Extended description

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.

Root cause

How and when does the problem arise?

Lifecycle phase

Architecture and Design

COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.

Risk

What does successful exploitation lead to?

Gain Privileges or Assume Identity

Affected security scopes: Access Control

Messages sent with a capture-relay attack allow access to resources which are not otherwise accessible without proper authentication.

Defence

How is it prevented and fixed?

Architecture and Design

Architecture and design approach

Detail
Utilize 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.

Architecture and Design

Architecture and design approach

Detail
Since 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.