A high severity vulnerability exists within the Cisco Secure Client Software for Windows and Cisco AnyConnect Secure Mobility Client Software for Windows. This elevation of privileges flaw could enable an attacker to have SYSTEM level privileges to carry out further attacks on vulnerable systems. The Cisco Secure Client and Cisco AnyConnect Secure Mobility Client products are used for secure remote working through virtual private network access, also providing endpoint management and telemetry features for administrators to manage.  

This high severity vulnerability is tracked as CVE-2023-20178 and has been assigned a CVSS base score of 7.8. although this vulnerability is not currently believed to be exploited in the wild or have a public exploit disclosed, Cisco have stated in their security advisory that a potential exploit of this flaw could be conducted by a low-privileged, authenticated, local attacker. This flaw occurs due to improper permissions being assigned to a temporary directory, which is created during the client update process run after a successful VPN connection is established. A function of the Windows installer process can be used maliciously by an attacker to exploit this vulnerability and escalate their privileges to SYSTEM level, where they can then go on to execute arbitrary code at this high level.  

Cisco have confirmed that only the Windows software versions of these products are vulnerable, and that Cisco AnyConnect Secure Mobility Client for Linux and MacOS, Cisco Secure Client-AnyConnect for Android, Cisco Secure Client AnyConnect VPN for iOS, and Cisco Secure Client for Linux and MacOS are not affected by this flaw. The use of the Windows installer process in this potential exploit may be the reason other software versions on other operating systems are not affected by this flaw.  

There are no workarounds that can be used to address this vulnerability, so the only mitigation option is to apply the relevant software update to patch this flaw. The first fixed release for Cisco AnyConnect Secure Mobility Client for Windows Software is version 4.10MR7 (4.10.07061), and the first fixed release for Cisco Secure Client for Windows Software is version 5.0MR2 (5.0.02075). Customers are advised to update affected products to these recent releases, or later versions, in order to apply the security patches to fix this flaw.