Bug ID 904053: Unable to set ASM Main Cookie/Domain Cookie hashing to Never

Last Modified: Sep 18, 2020

Bug Tracker

Affected Product:  See more info
BIG-IP ASM(all modules)

Known Affected Versions:
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, 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, 14.1.0, 14.1.0.1, 14.1.0.2, 14.1.0.3, 14.1.0.5, 14.1.0.6, 14.1.2, 14.1.2.1, 14.1.2.2, 14.1.2.3, 14.1.2.4, 14.1.2.5, 14.1.2.6, 14.1.2.7, 15.0.0, 15.0.1, 15.0.1.1, 15.0.1.2, 15.0.1.3, 15.0.1.4, 15.1.0, 15.1.0.1, 15.1.0.2, 15.1.0.3, 15.1.0.4, 15.1.0.5, 16.0.0, 16.0.0.1

Opened: Apr 26, 2020
Severity: 3-Major

Symptoms

Disabling ASM Main Cookie/Domain Cookie hashing in a Policy's Learning and Blocking Setting with 'Never (wildcard only)' does not stop the ASM Main Cookie from continuing to hash server-provided cookies.

Impact

A sufficient number of ASM Main Cookies and/or a sufficiently large number of cookies for each ASM Main cookie to hash can result in the HTTP header becoming prohibitively large, causing traffic to be refused by the server.

Conditions

-- ASM enabled. -- Learning mode enabled for Policy. -- Learn New Cookies set to 'Never (wildcard only)' instead of default 'Selective'.

Workaround

Disable Learning mode for the Policy disables Cookie hashing. Note: This affects all learning, not just Cookie hashing.

Fix Information

None

Behavior Change