WORM_SLENFBOT.LH

This worm arrives via removable drives. It 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.

It executes commands from a remote malicious user, effectively compromising the affected system.

It does not have any information-stealing capability.

Arrival Details

This worm arrives via removable drives.

It 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%\wmphb32.exe (with Admin Rights)
• %User Profile%\Network\wmphb32.exe (without Admin Rights)

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

It creates the following folders:

• %User Profile%\Network - (without Admin Rights)

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

It injects codes into the following process(es):

• explorer.exe

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
Windows Host Network = "%System%\wmphb32.exe" (with Admin Rights)

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Windows Host Network = "%User Profile%\Network\wmphb32.exe" (without Admin Rights)

Other System Modifications

This worm adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\AppCompatFlags (without Admin Rights)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\AppCompatFlags (with Admin Rights)

It adds the following registry entries:

HKEY_CURRENT_USER\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%User Profile%\Network\wmphb32.exe = "%User Profile%\Network\wmphb32.exe:*:Windows Host Network" (without Admin Rights)

HKEY_CURRENT_USER\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%User Profile%\Network\wmphb32.exe = "%User Profile%\Network\wmphb32.exe:*:Windows Host Network" (without Admin Rights)

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\AppCompatFlags\
Layers
%User Profile%\Network\wmphb32.exe = "DisableNXShowUI" (without Admin Rights)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\AppCompatFlags\
Layers
%System%\wmphb32.exe = "DisableNXShowUI" (with Admin Rights)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%System%\wmphb32.exe = "%System%\wmphb32.exe:*:Windows Host Network" (with Admin Rights)

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\wmphb32.exe = "%System%\wmphb32.exe:*:Windows Host Network" (with Admin Rights)

Propagation

This worm creates the following folders in all removable drives:

• {drive letter}:\SysRom.{645FF040-5081-101B-9F08-00AA002F954E}

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

• {drive letter}:\drvmon64.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:

[Autorun]
open=drvmon64.exe
icon=%windir%\system32\SHELL32.dll,3
action=Open thumbdrives to browse files.
shell\open=Open
shell\open\command=drvmon64.exe
shell\open\default=1
useautoplay=1

Backdoor Routine

This worm connects to any of the following IRC server(s):

• {BLOCKED}6.{BLOCKED}rog.su
• {BLOCKED}4.{BLOCKED}ore.su
• {BLOCKED}8.{BLOCKED}ore.su
• {BLOCKED}6.{BLOCKED}ore.su
• {BLOCKED}0.{BLOCKED}ore.su

It executes the following commands from a remote malicious user:

• Create/Open/Delete Files
• Create/Terminate Process
• Download/Upload files
• Join IRC

Download Routine

This worm accesses the following websites to download files:

• http://{BLOCKED}0.{BLOCKED}ackupsrv.su/net/5x2.zip - As of this writing, the server is still accessible but the file was already removed.

Information Theft

This worm does not have any information-stealing capability.

Other Details

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

• http://www.whatismyip.org

NOTES:
It drops the following files to removable drives:

• {drive letter}:\acm{number}.lnk
• {drive letter}:\i.cpl – detected as TROJ_STARTER.CM

It uses the following credentials when logging into its IRC server:

• NICK: {country}|X-672|0|{OS}|{number}
• USER: SPX
• PASSWORD: su1c1d3

It terminates the following running processes:

• teatimer.exe
• mrt.exe
• mrtstub.exe
• tcpview.exe
• hijackthis.exe
• msmpeng.exe
• msascui.exe
• mpcmdrun.exe
• usbguard.exe
• billy.exe
• aadrive32.exe

This worm terminates and deletes itself when the following conditions are met:

1. If file name contains any of the following string:

• malware
• sample
• sand-box
• sandbox
• test
• virus

2. If computer name of the affected system is any of the following:

• MORTE
• VMG-CLIENT
• Malekal
• HOME-OFF-D5F0AC
• DELL-D3E62F7E26
• KAKAPROU-6405DA

3. If user names found on the affected system are any of the following:

• morte
• vmg-client
• malekal
• home-off-d5f0ac
• dell-d3e62f7e26
• kakaprou-6405da
• klasnich

4. This worm enumerates entries from the following registry and check for the following virtual environment:

• HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Disk\Enum
• vmware
• vbox
• Virtual
• qemu

5. It checks if it running in a virtual environment by checking if any of the following files are running in memory:

• cports.exe
• dumpcap.exe
• filemon.exe
• procdump.exe
• procexp.exe
• procmon.exe
• regmon.exe
• regshot.exe
• sbiectrl.exe
• squid.exe
• syssafe.exe
• tcpview
• vbox
• vmsrvc
• vmware
• wireshark.exe

6. It also checks if opened windows or classes contain any of the following:

• CurrPorts
• Microsoft Network Monitor 3.3
• Process Monitor - Sysinternals: www.sysinternals.com
• PROCEXPL
• Regshot 1.8.2
• SmartSniff
• TCPViewClass
• The Wireshark Network Analyzer

7. It also checks if the following files exist:

• %Program Files%\Ethereal\ethereal.html
• %Program Files%\Microsoft Network Monitor 3\netmon.exe
• %Program Files%\WinPcap\rpcapd.exe
• %Program Files%\WireShark\rawshark.exe

It connects to the IRC servers using TCP port 6303.

It does not use specific commands for proxy server. However, it can still access the download URL if users have their own proxy server because proxy servers can interpret HTTP requests.

It does not have rootkit capabilities.

It does not exploit any vulnerability.