I usually do not write security advisories unless absolutely necessary. This time I should, however I have neither the time, nor the desire to do so. But Kaspersky did not react, so ... quick and dirty: Kaspersky Internet Security 2013 (and any other Kaspersky product which includes the firewall funcionality) is susceptible to a remote system freeze. As of the 3rd March 2013, the bug is still unfixed. If IPv6 connectivity to a victim is possible (which is always the case on local networks), a fragmented packet with multiple but one large extension header leads to a complete freeze of the operating system. No log message or warning window is generated, nor is the system able to perform any task. To test: 1. download the thc-ipv6 IPv6 protocol attack suite for Linux from www.thc.org/thc-ipv6 2. compile the tools with "make" 3. run the following tool on the target: firewall6 <interface> <target> <port> 19 where interface is the network interface (e.g. eth0) target is the IPv6 address of the victim (e.g. ff02::1) port is any tcp port, doesnt matter which (e.g. 80) and 19 is the test case number. The test case numbers 18, 19, 20 and 21 lead to a remote system freeze. Solution: Remove the Kaspersky Anti-Virus NDIS 6 Filter from all network interfaces or uninstall the Kaspersky software until a fix is provided. The bug was reported to Kaspersky first on the 21st January 2013, then reminded on the 14th Feburary 2013. No feedback was given by Kaspersky, and the reminder contained a warning that without feedback the bug would be disclosed on this day. So here we are. Greets, Marc Heuse -- Marc Heuse www.mh-sec.de PGP: FEDD 5B50 C087 F8DF 5CB9 876F 7FDD E533 BF4F 891A