Mailing-List: contact securesoftware-help@list.cr.yp.to; run by ezmlm Delivered-To: mailing list securesoftware@list.cr.yp.to Received: (qmail 48875 invoked by uid 1017); 15 Dec 2004 08:28:52 -0000 Date: 15 Dec 2004 08:28:52 -0000 Message-ID: <20041215082852.48874.qmail@cr.yp.to> Mail-Followup-To: securesoftware@list.cr.yp.to, lukem@netbsd.org Automatic-Legal-Notices: See http://cr.yp.to/mailcopyright.html. From: "D. J. Bernstein" To: securesoftware@list.cr.yp.to, lukem@netbsd.org Subject: [remote] [control] tnftp 20030825 does not check for directory escapes Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Yosef Klein, a student in my Fall 2004 UNIX Security Holes course, has discovered a remotely exploitable security hole in tnftp, an FTP client, version 20030825 (current at least in FreeBSD ports). I'm publishing this notice, but all the discovery credits should be assigned to Klein. You are at risk if you use tnftp to download a batch of files from an FTP server. Anyone who provides an FTP response to tnftp (not necessarily the legitimate server administrator; an attacker can modify FTP responses passing through the network) then has complete control over your account: he can read and modify your files, watch the programs you're running, etc. The bug is triggered by the server sending a file name with slashes, such as /home/you/.cshrc. The mget() function in cmds.c blindly uses the server's file name (cp) as a local file name (tp passed to recvrequest); users normally expect file-transfer programs to check for escapes from the current directory. ---D. J. Bernstein, Associate Professor, Department of Mathematics, Statistics, and Computer Science, University of Illinois at Chicago