Cisco’s WebEx software is affected by a serious vulnerability that can be exploited to execute arbitrary commands with elevated privileges.
The security hole was discovered by Ron Bowes and Jeff McJunkin of Counter Hack. The researchers dubbed the flaw WebExec and even set up a dedicated website for it at webexec.org.
The vulnerability, tracked as CVE-2018-15442, was reported to Cisco in early August and patches were released within two months. Cisco coordinated the disclosure of the flaw with the researchers and there is no evidence that it has been exploited for malicious purposes.
According to Cisco, the WebExec vulnerability affects Webex Meetings Desktop App prior to 33.6.0, and Webex Productivity Tools releases 32.6.0 and later, prior to 33.0.5.
Cisco says the flaw can be exploited by an authenticated, local attacker to execute arbitrary commands with SYSTEM privileges. However, the networking giant noted that remote exploitation may also be possible in Active Directory deployments through the operating system’s remote management tools.
“This is a pretty unique vulnerability, because it’s a remote vulnerability in a client application that doesn’t even listen on a port,” Bowes and McJunkin wrote. “The summary is: when the WebEx client is installed, it also installs a Windows service called WebExService that can execute arbitrary commands at SYSTEM-level privilege. Due to poor ACLs, any local or domain user can start the process over Window’s remote service interface (except on Windows 10, which requires an administrator login).”
The researchers have made available proof-of-concept (PoC) code for both Nmap and Metasploit, along with a tool that allows users to check if their systems are vulnerable. Technical details on the vulnerability have also been released.