An exploit attacks a critical Microsoft Agent vulnerability less than 24 hours after the patch came out.
An exploit that attacks a critical Microsoft Agent vulnerability was published less than 24 hours after Microsoft released a relevant security advisory in its Sept. 11 Patch Tuesday
set of releases.
The security advisory for Microsoft Agent, MS07-051
, was the only critical release out of four security advisories. It addresses a vulnerability whereby the Microsoft Agenta set of software services for developers to enhance the user interface of Web-based applicationscan get hoodwinked by a malicious URL and can then be used to take over a targeted system without ever appearing to the user.
Microsoft Agent (agentsvr.exe) is prone to the stack-based buffer-overflow vulnerability because it fails to adequately bound check user-supplied data. The issue occurs when the "agentdpv.dll" ActiveX control processes maliciously craft URLs, resulting in memory corruption.
If the exploit succeeds, the attacker gains system control. If it fails, a denial-of-service occurs.
Symantec has exploit code available to members of its Immunity Partners Program.
Click here to read more about a tool for rapidly writing flaw exploits.
Proof-of-concept code is also available here
For users who cant apply the patch
straight away, Symantec and Microsoft recommend the typical mitigation strategies when dealing with an exploit that requires user interaction:
Run software as a non-privileged user with minimal access rights, and always run non-administrative software as an unprivileged user with minimal access rights. Also, stay away from links coming from strangers or untrustworthy sources.
Keep out of sites that have questionable integrity. Set browser security to disable execution of script code or active content. Dont open e-mail from strangers or those whom you dont trust, given that attackers could exploit the vulnerability through HTML e-mail.
As a workaround, Symantec suggests setting the kill bit for the following CLSIDs to prevent instantiation of malicious Microsoft Agent ActiveX controls:
Microsoft describes how to disable ActiveX controls here
. Microsoft also suggests unregistering "AgentSvr.exe" as a workaround.
Check out eWEEK.coms Security Center for the latest security news, reviews and analysis. And for insights on security coverage around the Web, take a look at eWEEKs Security Watch blog.