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Microsoft issues out of band update for LNK

Microsoft will issue an out-of-band update next Monday, August 2nd. The update will address the critical LNK vulnerability that applies to all versions of the Windows Operating system, from Windows XP SP3 to Windows 7.

Microsoft’s decision to issue this upgrade before the normal Patch Tuesday on August 10 is due to reports of increasing number of attacks that use the LNK flaw.

Windows 2000 and XP SP2 users will not be covered and are now in a predicament that will become increasingly urgent. Attacks will continue to become more prevalent and their defensive options are limited. Microsoft’s work-around in Advisory KB2286198 has a serious impact on the usability of the system as desktop icons are all replaced by standard generic representations and navigation is hampered. The best option for XP SP2 users is to upgrade to SP3 as soon as possible, Windows 2000 users need to migrate to a new OS alltogether.

Primary attack vectors for the LNK vulnerability are USB sticks and shared drives, ahe attack depends on a specially crafted LNK file and a custom DLL to function. Remote attacks through e-mail or websites are theoretically possible, but require multiple steps and user interaction. Nevertheless disabling SMB and WebDAV protocols in the outbound ruleset of internet facing firewalls is a measure that provides additional protection against the remote attack vector.

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