TCP Traffic on Networks in Asia Redirected to Malicious Websites
IntelliShield: Applied Mitigation Bulletin
2009 March 06 22:14 GMT
2009 March 13 21:23 GMT
IntelliShield is updating this bulletin with information about the TCP traffic redirection attacks that are affecting networks in Asia.
Public reports are indicating that some TCP traffic that is passed through certain networks in Asia may be redirected to malicious websites. Full details of the attacks are unclear, but they could be a result of a malicious code outbreak, DNS compromise, non-blind TCP spoofing attacks, or another man-in-the-middle style of attack.
Non-blind TCP spoofing attacks refer to TCP attacks where attackers reside on the same subnet as the targeted user, or along the path of a user's traffic. Because the attacker has visibility into the victim's traffic, he or she can determine the sequence and acknowledge (SEQ/ACK) numbers; if these numbers are known, the attacker can accurately spoof the victim's desired destination. Successful spoofing could result in session hijacking, redirection, or other interference or inspection of the victim's traffic.
Non-blind TCP spoofing attacks take place between a user and the destination device or application when an attacker is attempting to locate valid SEQ/ACK packets. This type of attack could allow an attacker to redirect packets with valid SEQ/ACK numbers to a user, which may redirect the user's browser session to a malicious website. Public sources indicate that this website was hxxp://www.dachengkeji.com/aritcle/index.htm, but the URL has become unreachable. Attacks could redirect users to other malicious sites or compromised legitimate sites that may subsequently infect systems with malicious code or allow attackers to perform other malicious activities.
The following websites may redirect users:
www.msn.com.tw tw.msn.com taiwan.cnet.com
Users should also be aware of the possibility of web redirects and use caution even when visiting well-known and trusted websites. For assistance in verifying the authenticity of URLs, users can check the reputation of an IP address or domain using web reputation tools.
Version 3,March 12, 2009, 3:05 PM: IntelliShield is re-releasing this bulletin to include updated information about the TCP traffic redirection attacks on Taiwanese networks.
Version 2, March 11, 2009, 12:03 PM: IntelliShield is re-releasing the bulletin detailing the TCP traffic redirection attacks on Taiwanese networks to include updated information.
Version 1, March 6, 2009, 5:14 PM: Reports indicate that users attempting to browse to certain Taiwanese websites are being redirected to malicious websites.
The security vulnerability applies to the following combinations of products.
Security Activity Bulletin
Original Release Base
The urgency and severity ratings of this alert are not tailored to individual users; users may value alerts differently based upon their network configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.