Exploit Code Arises for Latest Windows Flaws

Malicious code adds more fuel to the fears that another Windows worm is on the horizon.

Adding more fuel to the fears that another Windows worm is on the horizon, security experts said Tuesday afternoon that they have seen working exploit code in the wild for the latest pair of vulnerabilities in the Windows RPC DCOM interface.

The discovery of the code, which can be used to attack the two buffer overrun flaws in the interface, comes just two days after someone posted to a security mailing list exploit code for a denial-of-service weakness in the same interface. The RPC DCOM problems are particularly troubling and potentially dangerous because they affect nearly every current version of Windows, including the new Windows Server 2003.

A previously discovered buffer overrun in the interface was exploited by the Blaster worm that tore through the Internet in August.

The newly released exploit code gives attackers the ability to get privileged access to vulnerable machines and also allows for the creation of a new account with a preset password. The exploit tool also gives attackers the option of targeting specifically configured machines, i.e., Windows 2000 Service Pack 3 or machines that have the patch for the original RPC DCOM flaw installed but not the fix for the more recent vulnerabilities, according to an analysis by iDefense Inc., based in Reston, Va.

Ken Dunham, malicious code manager at iDefense, said he expects to see widespread compromise of vulnerable PCs in the next few days and also anticipates the release of a worm based on this code. The exploit code has been posted to at least one well-known cracker Web site.

"Weve seen it, weve brought it into the lab and it works. We havent seen any infections yet, but its only a matter of time before it gets going in the wild," said Bruce Schneier, CTO and founder of Counterpane Internet Security Inc., in Cupertino, Calif., a managed security monitoring provider. "When [a new worm] hits, its likely to be a fast-spreader. Someone could just take the old Blaster code, rip out the old infection mechanism, drop this one in, and youre done."

The new code exploits two buffer overruns in the Remote Procedure Call (RPC) Distributed Component Object Model (DCOM) interface in Windows. Specifically, the problems lie in the portion of the service that handles RPC messages for the activation of the DCOM. Microsoft Corp. released a patch for the flaws last week.

At the time the vulnerabilities were disclosed, many security experts said the flaws were ripe for a worm attack, given the widespread usage of Windows and the nearly identical nature of the problems to the flaw that Blaster attacks.

Discuss this in the eWEEK forum.