Bug ID 1017557: ASM Plugin Abort reset for chunked response without proper terminating 0 chunk followed by FIN

Last Modified: Sep 13, 2023

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

Known Affected Versions:
15.1.2, 15.1.2.1, 15.1.3, 15.1.3.1, 15.1.4, 15.1.4.1, 15.1.5, 15.1.5.1, 15.1.6, 15.1.6.1, 15.1.7, 15.1.8, 15.1.8.1, 15.1.8.2

Fixed In:
17.1.0, 16.1.4, 15.1.9

Opened: May 11, 2021

Severity: 3-Major

Symptoms

ASM BD sends a reset back to the client when the backend server sends a response without proper terminating 0 chunk followed by FIN.

Impact

Valid requests can be reset.

Conditions

- ASM provisioned - ASM policy attached to a virtual server - Backed server sends a bad chunked response

Workaround

Any one of the following workarounds can be applied. -- Fix backed server behavior. -- Fix bad response using iRule, appending proper terminating 0 chunk -- Change ASM internal /usr/share/ts/bin/add_del_internal update bypass_upon_load 1

Fix Information

Fix ASM to properly handle bad chunked response followed by FIN

Behavior Change

Guides & references

K10134038: F5 Bug Tracker Filter Names and Tips