Cisco Issues Web Security Appliance Security Updates

In early November Cisco made available security updates to resolve 3 CVEs (defined)(1x critical and 2x high severity) within their Web Security Appliances (WSA).

Why Should These Issues Be Considered Important?
The first and most serious vulnerability could allow an authenticated user (a user already with some level of access to your Cisco appliance) if they pass specific commands as arguments (parameters, defined) to the system scripts used to create certificates that will result in them obtaining root level access (defined) to your security appliance.

The remaining 2 high severity issues could result in a denial of service (DoS, defined) condition when exploited by a remote unauthenticated attacker (i.e. someone with no initial access to your security appliance). These issues are caused by failures to free (make available for use) memory during “opening multiple connections that request file ranges” and retrieving “data from the proxy server cache to terminate a TCP connection.” The result of these denial of service attacks would be your security appliance being temporarily unavailable to carry out it’s role within your organization.

The most severe security issue has no available workaround but the high severity issues have workarounds and indicators of compromise (IOC)(defined) to detect if attacks using these issues have occurred. At this time, the Cisco Product Security Incident Response Team (PSIRT) is not aware of any of these issues being used to attack its customers.

The affected appliances are as follows:

  • Critical issue: Cisco AsyncOS for the WSA versions 8.0 and later, both virtual and hardware versions
  • High severity issues: Cisco AsyncOS versions 8.0 through 8.8 for Cisco WSA on both virtual and hardware appliances.

Steps to determine if your appliances are affected are provided in the 3 Cisco security advisories mentioned below.

How Can I Protect Myself From These Issues?
If your organization uses any of the above mentioned Cisco Web Security Appliances please follow the directions within the 3 Cisco security advisories mentioned below to install the necessary security updates:

Cisco Web Security Appliance Certificate Generation Command Injection Vulnerability
Cisco Web Security Appliance Range Request Denial of Service Vulnerability Advisory 1
Cisco Web Security Appliance Range Request Denial of Service Vulnerability Advisory 2

Thank you.

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