The First Windows 7 Zero-Day Exploit

xploraiswakco writes with the first Microsoft-confirmed Windows 7 zero-day vulnerability, with a demonstration exploit publicly available. The problem is in SMBv2 and SMBv1 and affects Windows 7 and Windows Server 2008 R2, but not Vista, XP, or Windows Server 2003. A maliciously crafted URI could hard-crash affected machines beyond any remedy besides pushing the white button. "Microsoft said it may patch the problem, but didn't spell out a timetable or commit to an out-of-cycle update before the next regularly-scheduled Patch Tuesday of December 8. Instead, the company suggested users block TCP ports 139 and 445 at the firewall." Reader xploraiswakco adds, "As important as this the mentioned article is, it should also be pointed out that any IT staff worth their pay packet should already have port 139 blocked at the firewall, and probably port 445, too."

Comments

Re:Are you trolling?

[DarkOx]

I always thought that zero-day referred to the time between when an exploit was being used in the wild and the amount of time admins/endusers had to patch there systems.

In the case of an exploit floating about in the wild where there has been no patch made available is a zero day because I have had zero days to patch my systems before the potential for easy exploitation.

You need to block *outgoing* ports

[WD]

The article and summary are not clear, but you need to block *outoing* ports 139 and 445 at the firewall to help protect against this issue. The vulnerability is triggered by the system attempting to make an SMB connection to a malicious server. This can happen in a number of ways, such as viewing a web page in IE or viewing an email message in Outlook or Outlook Express.

If your firewall blocks outgoing 139 and 445, then the SMB connection attempt fails.