Last Modified: Apr 28, 2025
Affected Product(s):
BIG-IP LTM
Known Affected Versions:
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, 14.1.2.8, 14.1.3, 14.1.3.1, 14.1.4, 14.1.4.1, 14.1.4.2, 14.1.4.3, 14.1.4.4, 14.1.4.5, 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, 15.1.1, 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, 15.1.9, 15.1.9.1, 15.1.10, 15.1.10.2, 15.1.10.3, 15.1.10.4, 15.1.10.5, 15.1.10.6, 16.0.0, 16.0.0.1, 16.0.1, 16.0.1.1, 16.0.1.2, 16.1.0, 16.1.1, 16.1.2, 16.1.2.1, 16.1.2.2, 16.1.3, 16.1.3.1, 16.1.3.2, 16.1.3.3, 16.1.3.4, 16.1.3.5
Fixed In:
17.0.0, 16.1.4, 14.1.4.6
Opened: Dec 23, 2021 Severity: 3-Major
The SYN Cookies Status of a virtual server shows 'full-hardware', but the 'Total Software' counter of software SYN Cookies continues to increment together with the 'Total Hardware' SYN Cookie counter during a SYN flood attack.
A portion of the SYN flood attack is handled in software, which might have some performance impact.
Only BIG-IP hardware platform with multiple HSB modules are affected by this issue, and whether specific devices are affected depends on the platform, the BIG-IP software version, and the selected turboflex profile. To determine whether any given BIG-IP device has more than HSB module in operation, inspect the state of the epva_flowstat tmstat table. If more than one value is present in the mod_id (hsb module ID) column, then the device is affected by this issue For example, the following output shows a device with two HSB modules (identified as module 1 and module 2): $ tmctl -s tmm,mod_id,pdenum,slot_id epva_flowstat tmm mod_id pdenum slot_id --- ------ ------ ------- 0 1 0 0 1 1 8 0 2 2 0 0 3 2 8 0
N/A
All TMMs now correctly enter hardware SYN Cookie mode.