Cisco Adaptive Security Appliance (ASA) software and Cisco Firepower Threat Defense (FTD) software fails to properly parse SIP traffic, which can result in a denial-of-service condition on affected devices.
Cisco Adaptive Security Appliance (ASA) software and Cisco Firepower Threat Defense (FTD) software fails to properly parse SIP traffic, which can allow an attacker to trigger high CPU usage, resulting in a denial-of-service condition on affected devices. This vulnerability is exposed if SIP Inspection is enabled on affected devices, which is the default configuration on ASA devices. The Cisco SIP Inspection feature is advertised to "... enforce the sanity of the SIP messages, as well as detect SIP-based attacks."
By causing an affected Cisco device to parse specially-crafted SIP traffic, a remote, unauthenticated attacker may be able to trigger a denial-of-service condition on affected devices.
The CERT/CC is currently unaware of a practical solution to this problem. Please consider the following workarounds:
Disable SIP Inspection
According to the Cisco advisory:
To disable SIP inspection, configure the following:
Cisco ASA Software and Cisco FTD Software Releases 6.2 and later (in FTD 6.2 and later use Cisco FMC to add the following via FlexConfig policy):
no inspect sip
Cisco FTD Software Releases prior to 6.2:
configure inspection sip disable
This vulnerability was publicly reported by Cisco.
This document was written by Will Dormann.
|Date First Published:||2018-11-01|
|Date Last Updated:||2018-11-05 19:20 UTC|