WORM_AUTORUN.ZLK

This worm arrives via removable drives. It arrives by accessing affected shared networks.

It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

It drops copies of itself into all the removable drives connected to an affected system. It drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names. 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 via removable drives.

It arrives by accessing affected shared networks.

Installation

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

• %Application Data%\srtserv\{malware file name}.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It drops the following file(s)/component(s):

• %Application Data%\srtserv\sdata.dll - detected as RTKT_VERST.ZLK

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

Its DLL component is injected to the following process(es):

• running processes

It creates the following folders:

• %Application Data%\srtserv

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• KAENA_HOOK

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\Run
srtserv = %Application Data%\srtserv\{malware file name}.exe

Other System Modifications

This worm adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\MSrtn
value1 = {malware filename}.exe

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\MSrtn
value2 = {data}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Netlogon\Parameters
DynamicSiteName = Default-First-Site-Name

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\SafeBoot

Propagation

This worm drops copies of itself into all the removable drives connected to an affected system.

It drops copies of itself in the following shared folders:

• available shared folders

It drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names.

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:

[Auto Run]
Open={malware file name}.exe
UseAutoPlay=1
Action={characters}
shell\open\Command={malware file name}.exe
shell\open\Default=1
shell\explore\Command={malware file name}.exe

Download Routine

This worm accesses the following websites to download files:

• http://defaf663.{BLOCKED}mb.com/setx.txt
• http://{BLOCKED}rrent.info/data/taskx.txt

NOTES:
The .TXT files contain other links that leads to the download of possibly malicious files.

Its .DLL component has rootkit capabilities, which enables it to hide its related files, folders and processes.