Microsoft Uncovers Exchange Server 5.5 Vulnerability

A flaw in the version, for which Microsoft has released a patch, could allow an attacker to execute code on other clients' systems.

A flaw in an old but still popular version of Microsoft Exchange Server could allow an attacker to execute code on other clients systems, according to a security bulletin released Tuesday by Microsoft, along with a patch for the flaw.

The bulletin, designated MS04-026, was the sole new security bulletin Microsoft released Tuesday for the month of August. The single patch closely follows the public release of Windows XP Service Pack 2 (SP2).

The Exchange Server bulletin, which Microsoft deemed one of "moderate" severity, describes a potential remote code execution on Exchange 5.5 (SP4) through Outlook Web Access. Exchange Servers 2000 and 2003 are not vulnerable.

Proper use of authentication and secure network protocols to access Exchange Server make it more difficult to exploit, according to the bulletin.

But if an attacker were able to perform the attack, they could put spoofed content in the browser and proxy server caches of Outlook Web Access clients, and possibly cause the clients to perform cross-site scripting attacks.

The company on Tuesday also revised a security bulletin issued one month ago relating to a local privilege elevation vulnerability in the POSIX subsystems of Windows NT 4 and Windows 2000. The modification notes that Microsoft INTERIX 2.2 is also vulnerable.

Microsoft had issued an out-of-sequence security bulletin July 30 along with a cumulative update for Internet Explorer addressing the problems detailed in the bulletin.

That bulletin addressed three critical problems that could allow attackers to compromise users systems.

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