The Samba Team, a group that manages the open-source software, released patches on Monday and a new version of the software, Samba 2.2.8a, to address the vulnerability.
Samba is a widely used software package that enables users to access and use files, printers and other shared resources on a corporate intranet or on the internet.
Samba works with a variety of operating systems, including Linux, Unix, OpenVMS and OS/2 and allows files hosted on machines running those operating systems to share files with machines running versions of the Microsoft Windows operating system.
The buffer overflow vulnerability disclosed Monday by Digital Defense is caused by an improperly written function within the Samba code.
Buffer overflows occur when a process tries to store more data in a buffer, or temporary data storage area, than it was intended to hold. Malicious hackers can use buffer overflows to place and execute code on compromised machines.
The vulnerability has been known about within hacking circles for more than a month and was already being used to attack vulnerable systems on the internet before the Digital Defense advisory was released, a security expert said.
Digital Defense said that it detected an active exploit using the Samba vulnerability on a test system it set up on the internet.
However, Digital Defense may be to blame for some of those exploits.
Along with its advisory, Digital Defense accidentally posted its own exploit code, a script named "trans2root.pl" on its Security Tools page.
When run against a vulnerable system, the exploit provided by Digital Defense would give an attacker total access to the remote system.
"It was an unfortunate incident. We had an individual who was overzealous and released a script we had developed for internal development and testing of the vulnerability," said Rick Fleming, chief technology officer at Digital Defense.
The script was available for download from Digital Defense for approximately 12 hours, but no figures were available on how many copies of the file were downloaded during that time.
While it is common for Digital Defense to release tools that detect and test for the vulnerabilities the company uncovers, the trans2root.pl file was not an example of such a tool.
"Tools are usually a proof of concept. They're not things that anyone can run. You need a programming background to effectively use the tool," Fleming said.
In addition, Digital Defense usually waits at least a month after the release of a patch from the supplier to release a tool, depending on the severity of the vulnerability. In some cases, no tool is released.
Samba is a standard part of many Linux and Unix distributions including those released by Red Hat, MandrakeSoft and Debian. All previous versions of Samba up to version 2.2.8 are affected by the vulnerability.
Despite the fact that the vulnerability is widespread, it is unlikely that it could be exploited from remote users on the internet, according to Fleming.
Digital Defense urged Samba users to check their Samba servers for signs of compromise and to apply patches for the vulnerability or upgrade to Samba 2.2.8a at http://www.samba.org.