WORM_OTOTI.LEX

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

Arrival Details

This worm arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This worm drops the following copies of itself into the affected system:

• %System%\csrcs.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

It drops the following files:

• %User Temp%\suicide.bat - auto-delete component

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.)

Autostart Technique

This worm adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
csrcs = "%System%\csrcs.exe"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe csrcs.exe"

(Note: The default value data of the said registry entry is Explorer.exe.)

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
DRM\amty

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

• {random}.exe

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

;{garbage characters}
[AuTOrUn]
;{garbage characters}
open={random}.exe
;{garbage characters}
shell\open\Command={random}.exe
;{garbage characters}
shell\open\Default=1
;{garbage characters}

Backdoor Routine

This worm connects to the following URL(s) to send and receive commands from a remote malicious user:

• http://{BLOCKED}.com:5400/po.php
• http://{BLOCKED}.com:5400/banner.gif
• http://{BLOCKED}.236:4700/fruits.htm

Other Details

This worm connects to the following URL(s) to get the affected system's IP address:

• http://www.{BLOCKED}ismyip.com
• http://{BLOCKED}kip.dyndns.org

NOTES:

It also accesses several websites to obtain the names of top downloaded torrents. It uses the names for its dropped copies in Peer to Peer applications.

• http://{BLOCKED}piratebay.org/top/401
• http://{BLOCKED}ratebay.se/top/401
• http://{BLOCKED}hunt.com/torrents/?iht=5&ihs1=2&age=0

The dropped AUTORUN.INF is detected by Trend Micro as TROJ_OTORUN.SMJ.