____ / /\ /____/ \____ \ \ / /\ ______________ \____\ _/ \ __________________________________________________ __/__ /\ \ / Fate Research Labs Security Advisory \ \/ /\ /\/\ Networking Division \____\/__\/ \ \ \ \ /\ \ \____\/__\/ ----------------------------------------------------------------------------------- Details: DLink Firewall/Router Vulnerable to Malformed Fragmented Packets Advisory ID: F8-DLINK20010906 Issue date: 062001SEPT Fate Division: Networking Researcher: Jonas Position: Research Scientist Severity: Medium/High Vendor Status: Contacted: No Response Vendor Web Site: http://www.dlink.com Platform: Confirmed on D-Link 704 home broadband firewall/router. Exploit Available: http://www.fatelabs.com __________________________________________________________________________________ 1. Summary The popular home broadband sharing device Dl-704 by DLink Technologies can easily be DoS'ed through malformed fragmented packets. Utilizing any standard packet crafting tool for these packets, generating a large number of identical/incorrectly fragmented IP packets causing the router to immediately stop forwarding packets and after approx. 2 minutes will require a reboot. 1a. Fragmentation The DoS relies on an exploit involving IP fragmentation, which is a process whereby IP datagrams are subdivided into smaller data packets during transit. Fragmentation is required because every network architecture carries data in groups called frames, and the maximum frame size varies from network to network. When an IP datagram enters a network whose maximum frame size is smaller than the size of the datagram, it is split into fragments. Thereafter, the fragments travel separately to their destination, at which point they are re-assembled and processed. 3. Exploit Fate Research Labs felt it would be a waste of valuable resources to recreate the wheel. Why rewrite code that is already available? Jolt2.c or hping2 can be downloaded from your favorite neighborhood sploit store. These 2 tools will accomplish the same effect. 4. Patch Details Download new firmware. V2.56b6 or later will fix it. http://www.dlink.com.tw/2000e/download/download.htm The US site only holds V2.55b15. 5. Shouts! You bitches thought Fate Labs was dead?! In the words of M1ch34L J4cKs0N y0! "You ain't seen nuthin yet!" Shouts to ph33r, Denatus, Soundman, Punisher, the coolio rehashed, my buddy Loki, and all @fate labs! "Let them hate us, provided they fear us." Long live our reign! 6. Standard Hello To anti.security.is A big fuck you to the arrogant bastards at anti.security.is. You are nothing more than a gaggle of Beetlejuice elitists trying to keep your 0day spl0it-pot from being released. Look at the beliefs you stand for before judging the beliefs of others. You claim that your beliefs protect the security vendors by "eliminating the communication medium for new exploits?" Maybe if they knew that you wanted to stop full disclosure so you could keep using your 0day on their customers networks without fear of it publishing on Bugtraq, you wouldn't look like such heroes. "Save a bug?" Here's your fucking bug, its dead, we squashed it with our 31337 0day advisory. - Fate Research Labs Soldiers for Full Disclosure ____ / /_____ / // \ / / \ \ \ /.__/ \ \__ .\ //___\\ \ / \_____//________________________________________________________ \____/ F8