Microsoft Windows Server Service Remote Code Execution Vulnerability (MS08-067, CVE-2008-4250)

1. Apply Official Security Update

Immediately install the MS08-067 security patch provided by Microsoft for your specific OS version.

2. Network-Level Mitigation (Port Blocking)

Block inbound traffic to SMB and NetBIOS ports at the network perimeter and host firewalls.

• Ports to block: TCP 139, TCP 445, UDP 137, UDP 138

Example PowerShell command to block inbound SMB:

New-NetFirewallRule -DisplayName "Block SMB Inbound" -Direction Inbound -LocalPort 139,445 -Protocol TCP -Action Block

3. Intrusion Prevention System (IPS) Signatures

Enable network-based IDS/IPS signatures (e.g., Snort SID 14919) to detect and block malicious RPC path canonicalization requests.

This vulnerability (MS08-067) resides in the Server service (netsvcs) of Microsoft Windows, specifically within the path canonicalization implementation in netapi32.dll. When processing a remote path via RPC, the NetpathCanonicalize function fails to properly validate the length of the input string, leading to a stack-based buffer overflow (CWE-119).

An unauthenticated attacker can exploit this by sending a specially crafted RPC request over SMB (Server Message Block). Because this vulnerability requires no authentication or user interaction, it has been heavily exploited in the wild by self-propagating malware such as the Conficker worm and Gimmiv.A.