Bugtraq mailing list archives
RFC-1644 (fwd)
From: aleph1 () DFW NET (Aleph One)
Date: Mon, 6 Apr 1998 10:30:55 -0500
---------- Forwarded message ---------- Date: Sat, 4 Apr 1998 19:21:58 +0600 (ESS) From: Vasim Valejev <vasim () diaspro com> To: freebsd-security () FreeBSD ORG Subject: RFC-1644 Hi ! Transactions-TCP (RFC-1644) in FreeBSD (and other systems) can cause problems for security : 1. New variant of SYN-flood attack . Someone can send many T/TCP packets with fake originate address (any unreachable address) and overload (possible cause Denial-Of-Service) victim's server (for example - many T/TCP requests to telnet/ftp/http/etc daemons) . 2. Attack to r*-services (rshd/rlogind without kerberos-authentication) . Hacker can send T/TCP requests with originate address from /etc/hosts.equiv or .rhosts files . In some cases (computer with address from hacker's request can't send TCP-RST packet in time) it possible run commands on attacked target . My experiments shows what attacker just need 10-50 ms delay between victim sending SYN-ACK packet and receiving RST packet from trusted computer (it depends from algorithm rshd/rlogind , place DNS-server with reverse zone , etc) . This attack can be used on other tcp-services with authentication based on ip-address . RFC-1644 must die :( . My english too (*sigh*) . Just do 'sysctl -w net.inet.tcp.rfc1644=0' and forget about it :) . Vasim V. (2:5011/27 http://members.tripod.com/~Vasim VV86-RIPE)
Current thread:
- RFC-1644 (fwd) Aleph One (Apr 06)