Critical vulnerability discovered in Arcserve backup software

Arcserve has patched a critical authentication bypass in its Unified Data Protection product that gave attackers control over the software’s web administration interface, and led to a remote code execution (RCE) attack.

Discovered by researcher Juan Manuel Fernandez (@TheXC3LL) and MDSec’s Sean Doherty, CVE-2023-26258 affects UDP between version 7.0 and 9.0, and has been patched by Arcserve.

While exploring the login interactions between client and server, the two researchers spotted a variable called authUUID and method called validateUserByUuid.

They were then able to use that information to obtain access; as they described in this post, they got “a cookie with a session.”

From there, the researchers were then able to retrieve and decrypt the admin’s password, giving them complete control over the system, including RCE capabilities.

Fernandez and Doherty have posted their attack tools at GitHub.

According to the MDSec post, the pair first disclosed their findings to Arcserve on February 9, and the company posted its patch on June 27.

Arcserve said all UDP Windows agents and Recovery Point Servers need to be upgraded to 9.1, manually or via an automatic update.