Windows Explorer / Internet Exporer Long Share Name Buffer Overflow

Secunia Advisory: SA11482    
Release Date: 2004-04-26 

Critical: Highly critical 
Impact: System access
Where: From local network


Microsoft Windows 2000 Advanced Server
Microsoft Windows 2000 Datacenter Server
Microsoft Windows 2000 Professional
Microsoft Windows 2000 Server
Microsoft Windows 95
Microsoft Windows 98
Microsoft Windows 98 Second Edition
Microsoft Windows Millenium
Microsoft Windows XP Home Edition
Microsoft Windows XP Professional


Microsoft Internet Explorer 5.01
Microsoft Internet Explorer 5.5
Microsoft Internet Explorer 6

Rodrigo Gutierrez has discovered a vulnerability in Windows and Internet Explorer, which can be exploited by malicious people to compromise a user’s system.

The vulnerability is caused due to a boundary error, which can be triggered via Internet Explorer and Windows Explorer when connecting to a file server. This can be exploited to cause a buffer overflow by setting up a malicious share with an overly long name (about 300 bytes) containing no lower case characters.

Successful exploitation may potentially allow execution of arbitrary code on a user’s system but requires that the user is either tricked into connecting to a malicious file server, visit a malicious website, or follow a specially crafted link.

According to a Microsoft knowledge base article (see “Other References” section), the vulnerability should have been fixed in SP1 for Windows XP and SP4 for Windows 2000. However, the vulnerability has been confirmed on fully patched systems running Windows XP and Windows 2000.

The vulnerability reportedly also affect Windows 95, 98, and Me. It is currently unknown whether Windows NT4.0 and Windows 2003 are affected.

NOTE: Secunia would normally rate this kind of vulnerability as “Moderately critical”, since this kind of traffic should be restricted to a LAN via border routers and firewalls. However, this is not the case on many networks, which leads to the higher rating.

Restrict traffic in border routers and firewalls.

Disable “Client for Microsoft Networks” for network cards. This will impact file sharing functionality.

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