A security researcher has published proof-of-concept (PoC) code targeting a recently patched high-severity vulnerability in the Cisco AnyConnect Secure Mobility Client and Secure Client for Windows.
The software allows remote employees to connect to an organization’s network using a secure virtual private network (VPN) and provides monitoring capabilities.
Tracked as CVE-2023-20178 (CVSS score of 7.8), the security defect impacts the client update process of the software, allowing a local attacker with low-privileges to elevate their access and execute code with System privileges.
“This vulnerability exists because improper permissions are assigned to a temporary directory that is created during the update process. An attacker could exploit this vulnerability by abusing a specific function of the Windows installer process,” Cisco explains in an advisory.
At large, this is an arbitrary folder delete issue that can be triggered during the software update process, when a temporary folder is created to store copies of files that are being modified, to allow a rollback if the installation process is not completed.
An attacker with knowledge of this temporary folder can run an exploit containing an executable file designed to start an update process but trigger a rollback midway. At the same time, the exploit continuously attempts to replace the contents of the temporary folder with malicious files.
Once the update process halts, Windows attempts to restore the files in the temporary folder to their original location, but instead consumes the attacker’s malicious content.
This week, security researcher Filip Dragovic, who reported CVE-2023-20178 to Cisco, released a PoC that works in a similar manner, triggering an arbitrary file delete with System privileges.
The researcher says he tested the PoC on Secure Client version 5.0.01242 and AnyConnect Secure Mobility Client version 4.10.06079. Only the Windows iterations of the software are impacted.
Cisco addressed CVE-2023-20178 in early June with the release of AnyConnect Secure Mobility Client version 4.10.07061 and Secure Client version 5.0.02075.