A mega update for the widely used Excel spreadsheet program is the highlight of the latest batch of security patches issued by Microsoft on July 11.
One month after confirming that maliciously rigged Excel files were being used in targeted zero day attacks against businesses, Microsoft released a "critical" bulletin with patches for eight distinctly different Excel vulnerabilities.
The MS06-037 bulletin covers a wide range of "remote code execution" flaws that could let hackers take "complete control of the vulnerable client workstation."
"We recommend that customers apply the update immediately," Microsoft said.
Affected software packages include Office 2003 (SP1 and SP2), Office XP (SP3), Office 2000 SP3, Office 2004 for Mac and Excel v. X for Mac.
The Excel bulletin replaces the MS06-012 update issued in March 2006 to correct two more flaws in the way Office handles PNG and GIF image files.
The Microsoft Office software suite is a main focus of Julys Patch Day. In addition to the Excel bulletin, the company released MS06-038 to cover three malformed string parsing Office bugs and MS06-039 to correct two more flaws in the way Office handles PNG and GIF image files.
Over the last four months, the company has patched a whopping 19 flaws in the Microsoft Office software suite.
Microsoft has also slapped a "critical" rating on the MS06-036 bulletin that deals with a buffer overrun in the DHCP (Dynamic Host Configuration Protocol) Client service.
This could allow remote code execution on Windows 2000 SP4, Windows XP and Windows Server 2003, Microsoft warned.
Windows uses DHCP to reduce the complexity of administering network addresses but because of an unchecked buffer, Microsoft said an attacker could remotely hijack a compromised system to install programs; view, change, or delete data; or create new accounts with full user rights.
A fifth "critical" bulletin, MS06-035, also provides patches for a pair of remote code execution issues in the Windows Server Service.
Security experts believe one of the two Server Services bug —a heap overflow in Mailslot—could prove problematic.
"Thats the one to watch," said Marc Maiffret, chief hacking officer of eEye Digital Security. "Its a nasty wormable bug."
Affected OS versions includes Windows 2000 SP4, Windows XP and Windows Server 2003.
The July patch batch also includes:
- MS06-033—An "important" update with fixes for an information disclosure flaw in ASP.NET. This affects users of the Microsoft Windows NET Framework 2.0 and applies to Windows 2000 SP4, Windows XP and Windows Server 2003.
- MS06-034—Patches for a vulnerability in Microsoft Internet Information Services using ASP. This could allow remote code execution attacks but is only rated "important" because attackers would require valid logon credentials to launch a successful exploit.
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