Eight patches - five critical - in MS April patch batch

Microsoft issued eight patches - five critical - to deal with 12 vulnerabilities on Tuesday. Fixes for Windows, Internet Explorer, Word, MSN Messenger and an update for Microsoft Exchange (2000 and 2003) all featured in Microsoft's latest patch batch.

Vulnerabilities in Microsoft's TCP/IP stack that could allow remote code execution and denial of service (MS05-019) and a cumulative security update for Internet Explorer (MS05-020) both make the critical list. An MSN Messenger security flaw involving the processing of GIF files (MS05-022), a MS Word security glitch (MS05-023) and the Exchange flaw (MS05-021) that could allow hackers to run hostile code on vulnerable systems also earn Microsoft's highest warning category. US CERT has published a summary of these alerts here.

Qualys, the firm credited with finding the TCP/IP stack flaw, warns that the problem is not limited to Microsoft. The vulnerability in Internet Control Message Protocol (ICMP) messages makes it possible to reset or slow an established connection as explained in a UK National Information Security Co-ordination Centre UNIRAS alert here.

SP2 'block off'

Tuesday also marked the expiry of a Windows XP SP2 blocker tool. When Microsoft released SP2 in August 2004 it offered firms the opportunity to "hold off" automatic installation of SP2 while still receiving security patches. That suspension expired on 12 April but Microsoft reckons the effect on corporates will not be huge since large firms use their own deployment tools rather than relying on Microsoft's Automatic Update service. According to Microsoft's latest publicly released download figures, SP2 had been distributed to over 170m customers via download and CD by mid February 2005. ®

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