Bug ID 664714: Client-side challenge is changing POST parameter value under some circumstances

Last Modified: Sep 13, 2023

Affected Product(s):
BIG-IP ASM(all modules)

Known Affected Versions:
12.1.2, 12.1.3, 12.1.3.1, 12.1.3.2, 12.1.3.3, 12.1.3.4, 12.1.3.5, 12.1.3.6, 12.1.3.7, 13.0.0, 13.0.0 HF1, 13.0.0 HF2, 13.0.0 HF3, 13.0.1, 13.1.0, 13.1.0.1, 13.1.0.2, 13.1.0.3, 13.1.0.4, 13.1.0.5, 13.1.0.6, 13.1.0.7, 13.1.0.8, 13.1.1, 13.1.1.2, 13.1.1.3, 13.1.1.4, 13.1.1.5, 13.1.3, 13.1.3.1, 13.1.3.2, 13.1.3.3, 13.1.3.4, 13.1.3.5, 13.1.3.6, 13.1.4, 13.1.4.1, 13.1.5, 13.1.5.1, 14.0.0, 14.0.0.1, 14.0.0.2, 14.0.0.3, 14.0.0.4, 14.0.0.5, 14.0.1, 14.0.1.1

Fixed In:
12.1.4

Opened: May 15, 2017

Severity: 3-Major

Symptoms

A parameter arrives with a different value to the server than was sent from the client. Happens while a brute force attack or web scraping challenge or web scraping session client-side mitigation is happening,

Impact

The wrong parameter arrives to the application. In response, the application may stop working or have other errors.

Conditions

-- POST request with URL-decoded parameters. -- A parameter is escaped. -- A client-side challenge is returned for this request.

Workaround

N/A

Fix Information

Client-side challenge no longer changes POST parameter value under described circumstances.

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips