Update kills code-execution threat in Samba

Samba developers have warned of a software flaw that allows attackers to remotely execute malicious code on systems running the widely used file-sharing package.

Version 3.5.5, which was released on Tuesday, fixes the underlying buffer overrun in functions used to generate a credential known as a Windows Security ID. It can be exploited by sending a booby-trapped ID that overflows the stack variable and injects malicious code into memory.

It remains unclear how easy it is to exploit the bug. H D Moore, CSO of Rapid7 and chief architect of the Metasploit project, said the only vector he's been able to identify is an option known as quota support, which isn't enabled by default. Even when turned on, he added, an attacker would need a root password.

Moore said other possible openings included the file find, the get/set user quota, and active directory, but so far none of them has panned out.

Samba is used to share files across systems running Linux, Windows, and Mac OS X. The vulnerability affects Samba versions going back to 3.0, which was released more than five years ago. It was discovered during an internal audit.

Andrew Bartlett, the Cisco Systems employee who identified the bug, didn't return an email seeking additional details. ®