July 8, 2008
Multiple vendors' implementations of the DNS protocol are prone to a DNS-spoofing vulnerability because the software fails to securely implement random values when performing DNS queries.
Successfully exploiting this issue allows remote attackers to spoof DNS replies, allowing them to redirect network traffic and to launch man-in-the-middle attacks.
This issue affects Microsoft Windows DNS Clients and Servers, ISC BIND 8 and 9, and multiple Cisco IOS releases; other DNS implementations may also be vulnerable.
Block external access at the network boundary, unless external parties require service.
Ensure that only trusted hosts and networks can send DNS responses to affected computers.
Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Use NIDS to detect suspicious or anomalous network traffic. Monitor logs for signs of malicious activity.
The vendor has released an advisory along with fixes to address this issue. Please see the references for more information.
NOTE: There are several reports that various firewall and security gateway applications are adversely affected by the changes associated with the fixes for this issue. Some vendors recommend removing the Microsoft patch associated with this issue. Users are advised to use extreme caution and to thoroughly evaluate the impact of removing the patch before doing so.
UPDATE: Microsoft has released an updated advisory detailing known issues with their updates.
UPDATE (August 1, 2008): Reports indicate that the Apple update for OS X 10.4.11 may not fully address this issue; Symantec has not confirmed this. Please see the references for more information.
Dan Kaminsky of IOActive
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