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Sophos advises "Renepo" worm brings broad-spectrum anti-security attacks to Mac OS X

  • 25 October, 2004 14:33

<p>Sophos, a world leader in protecting businesses against spam and viruses, is advising Mac OX S administrators of an anti-security worm known as "Renepo". The worm does not have prodigious spreading powers (for example, it does not use peer-to-peer sharing, email or instant messaging to spread), but is full of anti-security programming.</p>
<p>For example, Renepo will turn off the OS X firewall and other security software; will download and install hacker tools for password sniffing and cracking; will make key system directories world-writeable; and will create an admin-level user for later system abuse. Renepo also turns off accounting and logging to help hide its presence.</p>
<p>"You do not want this thing in your OS X network," said Paul Ducklin, Asia Pacific Head of Technology for Sophos. "Renepo makes such a wide range of security-related changes that all security bets are off once you have been compromised. Because Renepo attempts to harvest user, configuration and password data for a wide range of applications, including FTP servers, web servers, browsers, the VNC remote control program and the operating system itself, it represents a huge security headache rolled into a single shell script."</p>
<p>As Ducklin points out however, there is a silver lining: "The Renepo virus is not in the wild, and can therefore be considered a shot across the bows rather than a clear and present danger. Hopefully, its existence will be a timely warning to any Mac users who still assume they are safe because the Bad Guys aren't interested in the Mac platform."</p>
<p>Technical details, including detection and recovery instructions, are included below. This information is also available on-line at:</p>
Paul Ducklin ( is available for comment:
+61 2 9409 9100 (tel)
+61 407 320 515 (mob)
+61 2 9409 9191 (fax)</p>
<p>Sophos's press contact at Gotley Nix Evans is:
Michael Henderson (
+61 2 9957 5555 (tel)
+61 413 054 738 (mobile)</p>
<p>---[begin SH/Renepo-A technical details]---</p>
<p>Name: SH/Renepo</p>
<p>Type: Bash shell script virus</p>
<p>OS targeted: Mac OS X</p>
* spreads via "share crawling" to mounted volumes
* downloads and installs additional malicious code
* disables system security features
* collects confidential system data, including passwords
* reports infections to a remote server
* creates a new admin-level user</p>
SH/Renepo is a shell script worm targeted at the Macintosh OS X platform. If run on your computer (either accidentally or by design), it copies itself to the local startup directory (/System/Library/StartupItems) and to any other mounted volumes, including other computers on your network. Renepo also makes infected StartupItems folders world-writeable, thus opening a dangerous backdoor on any system it infects.</p>
<p>Note that any attacker trying to plant this worm in your network would need to get root access on one of your boxes first, meaning that you would already be "owned". Nevertheless, Renepo collects into a single script a wide range of anti-security attacks. Once the worm has run on your computer, it will compromise system security in many ways, including:</p>
<p>* turning off system accounting and logging
* turning off the OS X firewall
* turning off software auto-updates
* turning off LittleSnitch (a security program for OS X)
* turning on filesharing
* turning on ssh
* making key system files world-writeable
* installing ohphoneX (a voice and video sharing program for OS X)
* installing John the Ripper (a password cracker)
* installing dsniff (a password sniffer)
* logging the IP numbers of infected computers to a remote server
* creating a directory in which to stash harvested data (/.info)
* harvesting application, user and system data
* collecting Windows password hashes from samba
* searching for VNC password information
* trawling for passwords in the swap file
* creating a new admin-level user (LDAP-daemon)</p>
<p>Looking for signs of infection:
The Renepo virus can spread using any filename, but always tries to copy itself to /SystemLibrary/StartupItems. Be sure to review this location for unwanted or malicious scripts.</p>
<p>The Renepo virus creates a directory named "/.info" in which to collect data such as password hashes and application configuration. The presence of this directory should be considered suspicious.</p>
<p>The Renepo virus attempts to create an admin-level user named "LDAP-daemon" with a password hash of "rQ3p5/hpOpvGE" and a user ID of 401. The presence of such an account should be considered suspicious.</p>
Since Renepo makes a wide range of changes to system security, a complete security review should be carried out on compromised computers. Be sure to turn back on any services disabled by the virus, including accounting, logging, firewall and auto-updates. Also look for files and directories with "777" (world-writeable) permissions, especially /etc/hostconfig, /etc/xinetd.d/shh and the various data files used by cron.</p>
<p>Assume that all passwords on your network have been compromised. Renepo attempts to harvest user, configuration and password data for a wide range of applications, including FTP servers, web servers, browsers, VNC and the operating system itself.</p>
<p>---[end SH/Renepo-A technical details]---</p>

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