Threat Description

Worm:​Solaris/Wanuk.A

Details

Aliases:Worm:​Solaris/Wanuk.A, Worm:​Solaris/Wanuk.A
Category:Malware
Type:Worm
Platform:Solaris

Summary



This malware uses a known vulnerability in Sun Solaris, the Sun Solaris TelNet Remote Authentication Bypass vulnerability. It uses adm and lp as its username.



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.

Network Disinfection

For general instructions on disinfecting a local network infection, please see Eliminating A Local Network Outbreak.



Technical Details



Upon execution, this malware drops the following files on /var/adm/sa/.adm:

  • .i86pc - worm component for Intel-based processors
  • .sun4 - worm component for Sparc-based processors
  • .lp-door.i86pc - backdoor component for Intel-based processors (Backdoor:Solaris/Wanukdoor.A)
  • .lp-door.sun4 - backdoor component for Sparc-based processors (Backdoor:Solaris/Wanukdoor.A)

Note: These files will be dropped regardless of the processor being used by the infected machine.This malware executes the following command "uname -m" to check the processor type of the targeted machine. If the return value is 14h, it is Intel-based processor, if it is 15h, it is Sparc-based processor. The following dropped files will be either a copy of .i86pc or .sun4: It will drop a copy and use one of the following filenames in /var/adm/sa/.adm:

  • devfsadmd
  • svcadm
  • cfgadm
  • kadmind
  • zoneadmd
  • sadm
  • sysadm
  • dladm
  • bootadm
  • routeadm
  • uadmin
  • acctadm
  • cryptoadm
  • inetadm
  • logadm
  • nlsadmin
  • sacadm
  • syseventadmd
  • ttyadmd
  • consadmd
  • metadevadm

And with one of the following filenames in /var/spool/lp/admins/.lp:

  • lpshut
  • lpsystem
  • lpadmin
  • lpmove
  • lpusers
  • lpfilter
  • lpstat
  • lpd
  • lpsched
  • lpc

Lastly in /var/spool/lp/admins/.lp, a copy of the backdoor component (Backdoor:Solaris/Wanukdoor.A)

  • .lp-door.i86pc - if the processor type is Intel
  • .lp-door.sun4 - if the processor type is Sparc

Autostart Mechanism

This malware creates the following cron job: echo 10 1 * * * (cd %s && cd %s && [ -x %s ] && PATH=. %s) >/dev/null 2>&1 & >> .crontab The above piece of code was used twice. It was used for the .adm files and .lp files. It can be rewritten as: echo 10 1 * * * (cd /var/adm/sa/ && cd .adm && [ -x {file dropped} ] && PATH=. {file dropped}) >/dev/null 2>&1 & >> .crontab And echo 10 1 * * * (cd /var/spool/lp/admins/.lp && cd .lp && [ -x {file dropped} ] && PATH=. {file dropped}) >/dev/null 2>&1 & >> .crontab This means that it will create a cron job that will start every day at 1:10am. It will execute the file dropped in /var/adm/sa/.adm or /var/spool/lp/admins/.lp and will be added to the PATH. ">/dev/null 2>&1" this code makes the execution in the terminal without any output.

Exploit

This malware uses a known vulnerability in Sun Solaris, the Sun Solaris TelNet Remote Authentication Bypass vulnerability. It uses adm and flp as its username.

Payload

Every 13th day of the month, this malware attempts to send any of the following messages using /usr/sbin/wall:

Otherwise, it will execute the following commands and process the output to possibly get a list of targeted IP addresses:

/usr/sbin/ifconfig -u4a
/usr/bin/netstat -f inet -rn

Note: It parses the output using the following strings:

  • netmask
  • inet
  • broadcast





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