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F-Secure Malware Information Pages: Worm:Solaris/Wanuk.A
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Summary
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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. |
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Disinfection
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Disinfection of Network Worms
A network worm uses local network (LAN) to spread itself, and to stop its spreading, it is advised to temporarily shut down a network until all workstations and servers are disinfected. A single infected workstation can reinfect the cleaned computers and ruin all previous disinfection attempts. However, if F-Secure Anti-Virus version 5.40 or a later version is installed on computers connected to a local network, it is recommended to set disinfection action of the On-Access Scanner (OAS) to 'Disinfect Automatically'. Such action will allow to protect the cleaned workstations connected to an infected network from further reinfection by a network worm.
For instructions on how to eliminate an outbreak of a network worm, please visit this page:
http://www.f-secure.com/v-descs/netdisinf.shtml |
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Detailed Description
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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:
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F-Secure Corporation |
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Last Modified: March 05, 2007
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