Microsoft Windows contains a vulnerability that could allow an unauthenticated, remote attacker to cause DNS services to store false entries within caches. Updates are available.
Description
Microsoft Windows contains a vulnerability that could allow an unauthenticated, remote attacker to cause DNS services to store false entries within caches.
This vulnerability exists due to errors when the vulnerable system handles malformed DNS responses. An unauthenticated, remote attacker could exploit this vulnerability by sending a malicious DNS response to the server. If successful, the attacker could poison the server DNS cache.
Microsoft has confirmed this vulnerability and released software updates.
Warning Indicators
The following Microsoft Windows-based systems running DNS services are affected:
Windows 2000 Server SP4
Windows Server 2003 SP2 and prior
Windows Server 2003 x64 Edition SP2 and prior
Windows Server 2003 for Itanium-based Systems with SP2 and prior
Windows Server 2008 for 32-bit Systems
Windows Server 2008 for x64-based Systems
IntelliShield Analysis
To exploit this vulnerability, an attacker must make repeated DNS query lookups of a targeted server. This type of activity could be observed and may indicate a possible ongoing exploit. If an exploit is successful, the attacker could cause the server to store false entries within the DNS cache. An attacker could cause the server to store false entries for financial websites or other sites in an attempt to redirect users to malicious sites, allowing the attacker to conduct phishing or spoofing attacks.
The Cisco Applied Intelligence team has created an Applied Mitigation Bulletin to address vulnerabilities that Microsoft disclosed in the March 2009 security bulletin release. This Cisco bulletin, which assists administrators in identifying or mitigating these vulnerabilities using Cisco devices, is available at the following link: Cisco Applied Mitigation Bulletin: Microsoft Security Bulletin Release for March 2009
The update available from Microsoft corrects this vulnerability by ensuring the DNS server properly handles repeated DNS lookups.
Vendor Announcements
Microsoft has released a security bulletin at the following link: MS09-008
Impact
An unauthenticated, remote attacker could exploit this vulnerability to write arbitrary DNS entries into DNS server caches. An exploit could allow the attacker to conduct spoofing or man-in-the-middle attacks.
Technical Information
This vulnerability exists due to errors when the vulnerable system handles malformed DNS responses. An unauthenticated, remote attacker could exploit this vulnerability by sending a malicious DNS response to the server. The processing of a malicious DNS response could cause a server to perform a large number of DNS lookups, returning a series of transaction identification numbers to the requestor. The attacker could gather the returned lookups and their related transaction IDs to determine future transaction numbers. The attacker could use the transaction numbers to send further requests that may poison the server DNS cache, causing it to store false entries that an attacker could leverage for phishing or man-in-the-middle attacks.
Safeguards
Administrators are advised to apply the appropriate updates.
Administrators are advised to restrict access to trusted users.
Administrators may consider employing network filtering devices to block malformed requests to vulnerable systems.
Patches/Software
Microsoft customers can obtain updates directly by using the links in the MS09-008 security bulletin. These updates are also distributed by Windows automatic update features and available on the Windows Update website. Microsoft Windows Server Update Services (WSUS), Systems Management Server, and System Center Configuration Manager can assist administrators in deploying software updates.
Signatures
Cisco Systems Cisco Intrusion Prevention System (IPS) 6.0
Datacenter Edition Base | Datacenter Edition, 64-bit Base | Enterprise Edition Base | Enterprise Edition, 64-bit Base | Standard Edition Base | Standard Edition, 64-bit Base | Web Server Base | Web Server, 64-bit Base
Associated Products:
N/A
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