From djb@cr.yp.to Wed Dec 15 14:23:38 2004
Date: 15 Dec 2004 08:35:05 -0000
From: D. J. Bernstein <djb@cr.yp.to>
To: securesoftware@list.cr.yp.to, bug@iglooftp.com
Subject: [remote] [control] IglooFTP 0.6.1 does not check for directory
    escapes

Yosef Klein, a student in my Fall 2004 UNIX Security Holes course, has
discovered a remotely exploitable security hole in IglooFTP, at least
version 0.6.1 (the current version 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 IglooFTP to download a batch of files, with
overwriting, from an FTP server. Anyone who provides an FTP response to
IglooFTP (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 download_selection_recursive() function in
ftplist.c blindly uses the server's file name as a local file name
(filename passed to IGLOO_download_from); 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