Threat Description

Adore

Details

Aliases:Adolff, Adore, Unix/Adore, Red worm, Linux/Adore
Category:Malware
Type:Worm
Platform:Linux

Summary



Adore is a worm, that spreads in Linux systems using four diffrent, known vulnerabilities already used by Ramen and Lion worms. These vulnerabilities concern BIND named, wu-ftpd, rpc.statd and lpd services.



Removal


Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

You may wish to refer to the Support Community for further assistance. You also may also refer to General Removal Instructions for a general guide on alternative disinfection actions.



Technical Details



When Adore is running, it scans for vulnerable hosts from random Class B subnets on the network. If vulnerable host is found, attempts to download the main worm part from a web server located in China, in a similar way that Lion worm does.

After the worm has been downloaded to the victim machine, it is stored in to "/usr/local/bin/lib/" directory and "start.sh" is executed launching the worm.

At the start, "start.sh" replaces "/bin/ps" with trojanized version that does not show processes that are part of the worm. The original "/bin/ps" command is copied "/usr/bin/anacron".

The script also replaces "/sbin/klogd" with a version that has a backdoor. The backdoor activates when it receives a ping packet with correct size, and opens a shell in the port 65535. Orginal "klogd" will be saved to "/usr/lib/klogd.o".

The worm sends sensitive system data, including contents of the "/etc/shadow" file to four different email addresses.

Adore also creates a script file "/etc/cron.daily/0anacron". This file will be executed by the cron daemon with the next daily run. At this time, the worm will remove itself from the system and restore the original "/bin/ps". All worm related processes except the backdoor will be shut down, and the system will be restarted if "/sbin/shutdown" exists. The backdoor will start after the system has been restarted as the "/sbin/klogd" still contains the backdoor.

All four vulnerabilities have been already fixed by different Linux vendors. Further information is available at:

Debian GNU/Linux: http://www.debian.org/security/

Linux Mandrake: http://www.linux-mandrake.com/en/security/

SuSE: http://www.suse.com/en/support/security/index.html

RedHat Linux: http://www.redhat.com/support/errata/

F-Secure Anti-Virus detects the Adore worm with the current updates.





Description Created: Analysis: Sami Rautiainen, F-Secure; April 2001


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