NGSEC: "As it is said in ettercap's home page 'Ettercap is a multipurpose sniffer/interceptor/logger for switched LAN'. Due to improper use of the memcpy() function, anyone can crash ettercap and execute code as root user... This vulnerability only exists on Linux version because on *BSD and MacOSX ettercap only works on ethernets devices."
Next Generation Security Technologies http://www.ngsec.com Security Advisory Title: Ettercap, remote root compromise ID: NGSEC-2002-1 Application: ettercap 0.6.3.1 and older (http://ettercap.sourceforge.net) Date: 05/02/2002 Status: Vendor Contacted, new fixed version released. Platform: Linux on interfaces with MTU > 2000 Author: FermÃn J. Serna Location: http://www.ngsec.com/docs/advisories/NGSEC-2002-1.txt Overview: --------- As it is said in ettercap's home page "Ettercap is a multipurpose sniffer/interceptor/logger for switched LAN". Due to improper use of the memcpy() function, anyone can crash ettercap and execute code as root user. Vulnerabiliy has been confirmed and exploited in ettercap's version 0.6.3.1. Older versions maybe vulnerable too. This vulnerability only exists on Linux version because on *BSD and MacOSX ettercap only works on ethernets devices. Technical description: ---------------------- Ettercap is composed of decoders which looks for user, passwords, communities and stuff alike. Several decoders (mysql, irc, ...) suffer the following problem: memcpy(collector, payload, data_to_ettercap->datalen); Collector is declared as: u_char collector[MAX_DATA]; Where MAX_DATA is: #define MAX_DATA 2000 Datalen is the data (after TCP/UDP header) length read from the interface. So on interfaces where MTU is higher than 2000 you can exploit ettercap. Since normal ethernets have MTU:1500 this bug can not be exploited due to unsupported defragmentation in ettercap, but may be crashed with a forged packet (ip->tot_len > MAX_DATA). Here are common MTU and interface types: 65535 Hyperchannel 17914 16 Mbit/sec token ring 8166 Token Bus (IEEE 802.4) 4464 4 Mbit/sec token ring (IEEE 802.5) 1500 Ethernet 1500 PPP (typical; can vary widely) Exploit for this vulnerability can be found at http://www.ngsec.com/downloads/exploits/ettercap-x.c Sample explotation could be also in loopback interfaces: MTU:16436 piscis:~# ettercap -NszC -i lo &  21887 piscis:~# ./ettercap-x 0 | nc localhost 3306 ettercap-0.6.3.1 xploit by FermÃn J. Serna Next Generation Security Technologies http://www.ngsec.com punt! piscis:~# telnet localhost 36864 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. id; uid=0(root) gid=0(root) groups=0(root),1(bin),2(daemon),3(sys),10(wheel) Recomendations: --------------- Upgrade to a newer ettercap version. Run ettercap on a secure environment. More advisories at: http://www.ngsec.com/advisories/ PGP Key: http://www.ngsec.com/labs.asc (c)Copyright 2002 NGSEC. All rights reserved.