Months after promising to tighten up its procedures for certifying third-party software drivers, Microsoft is still giving the green light to network interface card (NIC) drivers that leak sensitive user information from machines running Windows Server 2003, according to a prominent security company.
The allegations were made in an alert posted Monday by Next Generation Security Software (NGSSoftware) of Sutton, England.
Microsoft was unable to respond in time for this report.
At least two NIC drivers that shipped with Windows Server 2003 contain a security hole that leaks information stored on a system in Ethernet "frames" or streams of data sent over a network, according to the alert.
The alert identified the vulnerability in drivers for the VIA Technologies Rhine II ethernet controller and the Advanced Micro Devices (AMD) PCNet family of drivers, according to Chris Paget, the NGSSoftware researcher who wrote the alert.
The Rhine II and PCNet drivers were the only two tested by NGSSoftware. Many other Windows Server 2003 NIC drivers could also be affected, Paget said.
The problem reported by NGSSoftware is just a new variation on a vulnerability discovered by @stake, a security consulting company based in Cambridge, Mass., almost a year ago and revealed in January.
Institute of Electrical and Electronics Engineers (IEEE) standards specify that streams of information sent over an Ethernet network should be organized into "frames" that are at least 46 bytes long.
In cases where higher layer protocols such as IP (Internet Protocol) provide packet data that is less than 46 bytes long, the software device drivers are supposed to fill in the empty space in the Ethernet frame with unusable data such as strings of "0's" in a process known as "padding" the frame.
Researchers at @stake found that the software drivers written by many leading NIC manufacturers instead use real data pulled at random from a machine to pad the frames.
At the time, @stake researchers demonstrated the problem with messages assembled using ICMP (Internet Control Message Protocol), an extension of IP. Researchers captured passwords and Web browser session information from the filler information.
NGSSoftware found leaked data in padding for TCP (Transmission Control Protocol) exchanges. Other protocols may exhibit the same flaw as well, Paget said.
While the vulnerability does not affect information sent over the Internet, it could allow attackers on the same network as a machine that is vulnerable to sniff out passwords, account numbers or other information from that system, he said.
The problem is a "low risk" for most organizations, but could be a big problem for companies or organizations with secure servers running the Windows platform.
"If you're a government with top secret information or you have a security-sensitive server, it could allow someone on the same network as the server to get information out of it," Paget said.
Microsoft does not produce NIC drivers for its operating systems, relying on the NIC hardware manufacturer and other third party companies to do that using specifications provided by the Redmond, Wash.-based company.
