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    SubjectLinux Worm (fwd)
    I'm annoyed when persons post virus alerts to unrelated lists but this
    is a serious threat. If your offended flame away.


    March 23, 2001 7:00 AM

    Late last night, the SANS Institute (through its Global Incident
    Analysis Center) uncovered a dangerous new worm that appears to be
    spreading rapidly across the Internet. It scans the Internet looking
    for Linux computers with a known vulnerability. It infects the
    vulnerable machines, steals the password file (sending it to a site), installs other hacking tools, and forces the newly
    infected machine to begin scanning the Internet looking for other

    Several experts from the security community worked through the night to
    decompose the worm's code and engineer a utility to help you discover
    if the Lion worm has affected your organization.

    Updates to this announcement will be posted at the SANS web site,


    The Lion worm is similar to the Ramen worm. However, this worm is
    significantly more dangerous and should be taken very seriously. It
    infects Linux machines running the BIND DNS server. It is known to
    infect bind version(s) 8.2, 8.2-P1, 8.2.1, 8.2.2-Px, and all
    8.2.3-betas. The specific vulnerability used by the worm to exploit
    machines is the TSIG vulnerability that was reported on January 29,

    The Lion worm spreads via an application called "randb". Randb scans
    random class B networks probing TCP port 53. Once it hits a system, it
    checks to see if it is vulnerable. If so, Lion exploits the system using
    an exploit called "name". It then installs the t0rn rootkit.

    Once Lion has compromised a system, it:

    - Sends the contents of /etc/passwd, /etc/shadow, as well as some
    network settings to an address in the domain.
    - Deletes /etc/hosts.deny, eliminating the host-based perimeter
    protection afforded by tcp wrappers.
    - Installs backdoor root shells on ports 60008/tcp and 33567/tcp (via
    inetd, see /etc/inetd.conf)
    - Installs a trojaned version of ssh that listens on 33568/tcp
    - Kills Syslogd , so the logging on the system can't be trusted
    - Installs a trojaned version of login
    - Looks for a hashed password in /etc/ttyhash
    - /usr/sbin/nscd (the optional Name Service Caching daemon) is
    overwritten with a trojaned version of ssh.

    The t0rn rootkit replaces several binaries on the system in order to
    stealth itself. Here are the binaries that it replaces:

    du, find, ifconfig, in.telnetd, in.fingerd, login, ls, mjy, netstat,
    ps, pstree, top

    - "Mjy" is a utility for cleaning out log entries, and is placed in /bin
    and /usr/man/man1/man1/lib/.lib/.
    - in.telnetd is also placed in these directories; its use is not known
    at this time.
    - A setuid shell is placed in /usr/man/man1/man1/lib/.lib/.x


    We have developed a utility called Lionfind that will detect the Lion
    files on an infected system. Simply download it, uncompress it, and
    run lionfind. This utility will list which of the suspect files is on
    the system.

    At this time, Lionfind is not able to remove the virus from the system.
    If and when an updated version becomes available (and we expect to
    provide one), an announcement will be made at this site.

    Download Lionfind at


    Further information can be found at:, CERT Advisory CA-2001-02,
    Multiple Vulnerabilities in BIND ISC BIND 8 contains buffer overflow
    in transaction signature (TSIG) handling code Information about the t0rn rootkit.
    The following vendor update pages may help you in fixing the original BIND

    Redhat Linux RHSA-2001:007-03 - Bind remote exploit
    Debian GNU/Linux DSA-026-1 BIND
    SuSE Linux SuSE-SA:2001:03 - Bind 8 remote root compromise. txt.txt
    Caldera Linux CSSA-2001-008.0 Bind buffer overflow

    This security advisory was prepared by Matt Fearnow of the SANS
    Institute and William Stearns of the Dartmouth Institute for Security
    Technology Studies.

    The Lionfind utility was written by William Stearns. William is an
    Open-Source developer, enthusiast, and advocate from Vermont, USA. His
    day job at the Institute for Security Technology Studies at Dartmouth
    College pays him to work on network security and Linux projects.

    Also contributing efforts go to Dave Dittrich from the University of
    Washington, and Greg Shipley of Neohapsis

    Matt Fearnow
    SANS GIAC Incident Handler

    If you have additional data on this worm or a critical quetsion please
    ------------ Output from pgp ------------
    Signature by unknown keyid: 0xA1694E46

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