A Vulnerability in Cisco Adaptive Security Appliance and Firepower Threat Defense Could Allow for Security Bypass

ITS Advisory Number: 
2021-139
Date(s) Issued: 
Friday, October 29, 2021
Subject: 
A Vulnerability in Cisco Adaptive Security Appliance and Firepower Threat Defense Could Allow for Security Bypass
Overview: 

A vulnerability has been discovered in Cisco Adaptive Security Appliance and Firepower Threat Defense, which could allow attackers to bypass security mechanisms on the system. Successful exploitation of this vulnerability could allow an unauthenticated remote attacker to bypass security mechanisms on the targeted host.

 

THREAT INTELLIGENCE:

There are currently no reports of this vulnerability being exploited in the wild.

 

Systems Affected: 
  • Cisco Adaptive Security Appliance (ASA) Software 9.7 and earlier.
  • Cisco Adaptive Security Appliance (ASA) Software prior to 9.8.4.40
  • Cisco Adaptive Security Appliance (ASA) Software prior to 9.12.4.25
  • Cisco Adaptive Security Appliance (ASA) Software prior to 9.14.3.1
  • Cisco Adaptive Security Appliance (ASA) Software prior to 9.15.1.17
  • Cisco Adaptive Security Appliance (ASA) Software prior to 9.16.1.28
  • Cisco Adaptive Security Appliance (ASA) Software 9.9, 9.10, and 9.13
  • Cisco Firepower Threat Defense (FTD) Software 6.3 and earlier
  • Cisco Firepower Threat Defense (FTD) Software prior to 6.4.0.13
  • Cisco Firepower Threat Defense (FTD) Software prior to 6.6.5
  • Cisco Firepower Threat Defense (FTD) Software prior to 6.7.0.3
  • Cisco Firepower Threat Defense (FTD) Software prior to 7.0.1
  • Cisco Firepower Threat Defense (FTD) Software prior to 7.0.1
  • Cisco Firepower Threat Defense (FTD) Software 6.5
RISK
GOVERNMENT
Large and medium government entities: 
High
Small government entities: 
High
BUSINESS
Large and medium business entities: 
High
Small business entities: 
High
Home Users: 
Low
Description: 

A vulnerability has been discovered in Cisco Adaptive Security Appliance and Firepower Threat Defense, which could allow attackers to bypass security mechanisms on the system. The vulnerability is the result of a design error in the identity-based firewall (IDFW) rule processing feature of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software, which could allow an unauthenticated, remote attacker to bypass security protections (CVE-2021- 34787). Attackers may be able to exploit this issue by sending a specially crafted network request to an affected device.

Actions: 
  • After appropriate testing, immediately install the update provided by Cisco.
  • Run all software as a non-privileged user (one without administrative privileges) to diminish the effects of a successful attack.
  • Remind users not to visit websites or follow links provided by unknown or untrusted sources.
  • Inform and educate users regarding the threats posed by hypertext links contained in emails or attachments especially from un-trusted sources.
  • Apply the Principle of Least Privilege to all systems and services.