Analysis by: Christopher Daniel So

 PLATFORM:

Linux, UNIX, Mac OS X

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet

This backdoor connects to Internet Relay Chat (IRC) servers. It joins an Internet Relay Chat (IRC) channel. It executes commands from a remote malicious user, effectively compromising the affected system.

  TECHNICAL DETAILS

File Size: 66,395 bytes
File Type: Script
Memory Resident: Yes
Initial Samples Received Date: 01 Feb 2011
Payload: Connects to URLs/IPs

Arrival Details

This backdoor may be downloaded from the following remote sites:

  • http://{BLOCKED}host.us/bots/pl

This malware arrives via the following means:

Backdoor Routine

This backdoor connects to any of the following Internet Relay Chat (IRC) servers:

  • linksys.{BLOCKED}shellz.net:25
  • irc.{BLOCKED}-newbie.org:6667
  • irc.{BLOCKED}thien.net:6667
  • {BLOCKED}2.{BLOCKED}7.181.100:53
  • {BLOCKED}briel.{BLOCKED}u.cc:8080
  • {BLOCKED}7.{BLOCKED}4.250.46:80
  • {BLOCKED}za.{BLOCKED}briel.{BLOCKED}u.cc
  • {BLOCKED}h.rocks
  • irc.{BLOCKED}net.com:6667

It joins any of the following Internet Relay Chat (IRC) channels:

  • #shellshock
  • #bug
  • #DNC
  • #w00t
  • #fr2
  • #113
  • #vafe
  • #cabal
  • #scan
  • #exit

It executes the following commands from a remote malicious user:

  • multiscan - Scan sites for multi-scan vulnerabilities
  • socks5 - Set up SOCKSv5 protocol and return an IP address
  • sql2 - Scan for sites with vulnerable SQL server
  • portscan - Scan an IP address for the following ports: 15, 19, 98, 20, 21, 22, 23, 25, 37, 39, 42, 43, 49, 53, 63, 69, 79, 80, 101, 106, 107, 109, 110, 111, 113, 115, 117, 119, 135, 137, 139, 143, 174, 194, 389, 389, 427, 443, 444, 445, 464, 488, 512, 513, 514, 520, 540, 546, 548, 565, 609, 631, 636, 694, 749, 750, 767, 774, 783, 808, 902, 988, 993, 994, 995, 1005, 1025, 1033, 1066, 1079, 1080, 1109, 1433, 1434, 1512, 2049, 2105, 2432, 2583, 3128, 3306, 4321, 5000, 5222, 5223, 5269, 5555, 6660, 6661, 6662, 6663, 6665, 6666, 6667, 6668, 6669, 7000, 7001, 7741, 8000, 8018, 8080, 8200, 10000, 19150, 27374, 31310, 33133, 33733, 55555
  • logcleaner - Deletes all files in the following directories:
    • /var/log/lastlog
    • /var/log/wtmp
    • /etc/wtmp
    • /var/run/utmp
    • /etc/utmp
    • /var/log
    • /var/logs
    • /var/adm
    • /var/apache/log
    • /var/apache/logs
    • /usr/local/apache/log
    • /usr/local/apache/logs
    • /root/.bash_history
    • /root/.ksh_history
  • sendmail - Send an email to a target
  • system - Get OS name and version, system uptime, current process name, user ID, group ID and current directory
  • cleartmp - Delete all files in /tmp
  • rootable - Enumerates possible root exploits in the infected system
  • nmap - Search an IP address for open ports in a specified range
  • back - Execute a remote shell (/bin/sh)
  • packetstorm - Enumerate advisories in http://www.packetstormsecurity.org/whatsnew20.xml
  • milw0rm - Enumerate exploits listed in milw0rm's website
  • udpflood - Perform UDP flooding
  • tcpflood - Perform TCP flooding
  • httpflood - Perform HTTP flooding
  • sqlflood - Perform SQL flooding
  • killme - Disconnect from the IRC server and terminate self
  • join - Join a channel
  • part - Leave a channel
  • reset - Disconnect from the IRC server
  • voice - Grant a user the voice status
  • owner - Grant a user channel ownership
  • deowner - Revoke a user's channel ownership
  • devoice - Revoke a user's voice status
  • halfop - Grant a user the half operator status
  • dehalfop - Revoke a user's half operator status
  • op - Grant a user the operator status
  • deop - Revoke a user's operator status
  • msgflood - Perform private message flooding to a target
  • dccflood - Perform DCC flooding to a target
  • ctcpflood - Perform TCP flooding to a target
  • noticeflood - Perform a NOTICE message flooding to a target
  • channelflood - Join 25 random IRC channels
  • maxiflood - Perform msgflood, ctcpflood and noticeflood simultaneously

NOTES:

This backdoor changes its process name to usr/sbin/httpd. It uses the IRC nickname ontet and ald.

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 7.806.11
FIRST VSAPI PATTERN DATE: 01 Feb 2011

Restart in normal mode and scan your computer with your Trend Micro product for files detected as PERL_SHELBOT.SMO. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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