WORM_RBOT.AHL

Malware type: Worm

Aliases: W32/Sdbot.worm.gen.as (McAfee), W32.Spybot.Worm (Symantec), Worm/Rbot.328262 (Avira), W32/Rbot-Fam (Sophos), Backdoor:Win32/Sdbot (Microsoft)

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 95, 98, ME, NT, 2000, XP

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

Low

Description: 

Worms are malicious programs that are able to replicate independently across a network, through email, IRC, or Peer-to-peer applications. They do not infect other files on a computer.

This variant of the WORM_RBOT family of worms mainly propagate through network shares. Upon execution, it drops a copy of itself as the file DEVSRV.EXE in the Windows system folder. It then attempts to place copies of itself into accessible shared folders across a network. It may attempt to use its own compiled list of user names and passwords in order to access shared folders that are password protected.

It also takes advantage of the following Windows vulnerabilities to propagate:

  • Buffer Overflow in SQL Server 2000
  • IIS5/WEBDAV vulnerability
  • RPC DCOM buffer overflow vulnerability
  • LSASS buffer overrun vulnerability

For more information regarding these vulnerabilities, please refer to the following Microsoft Web pages:

It also has backdoor capabilities. It comes with a built-in Internet Relay Chat (IRC) bot that allows it to connect to an IRC server. It then waits for commands from a remote user. Once connected, the remote user gains virtual control of the affected system.

Through this backdoor, the remote user can command the affected system to conduct distributed denial of service (DDoS) attacks, steal the CD keys from certain PC games, and other malicious actions.

It runs on Windows 95, 98, ME, NT, 2000, and XP.

For additional information about this threat, see:

Description created: Jan. 14, 2005 2:54:14 AM GMT -0800


TECHNICAL DETAILS


Size of malware: 259,570 Bytes

Initial samples received on: Jan 14, 2005

Payload 1: Compromises system security

Payload 2: Steals CD keys

Details:

Installation and Autostart Techniques

Worms are malicious programs that are able to replicate independently across a network, through email, IRC, or Peer-to-peer applications. They do not infect other files on a computer.

This variant of the WORM_RBOT family of worms mainly propagate through network shares. Upon execution, it drops a copy of itself as the file DEVSRV.EXE in the Windows system folder. It then attempts to place copies of itself into accessible shared folders across a network.

It creates the following registry entries to ensure it automatically executes during every Windows startup:

HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\Run
Device Microsoft System = �DEVSRV.EXE�

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\Run
Device Microsoft System = �DEVSRV.EXE�

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\RunServices
Device Microsoft System = �DEVSRV.EXE�

Other Registry Modifications

This worm also modifies the following registry entries:

HKEY_LOCAL_MACHINE\Software\Microsoft\OLE
EnableDCOM = "Y"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa
Restrictanonymous = "dword:00000000"

These entries are modified to (respectively):

HKEY_LOCAL_MACHINE\Software\Microsoft\OLE
EnableDCOM = "N"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa
Restrictanonymous = "dword:00000001"

Propagation via Network Shares

This worm propagates by dropping copies of itself into accessible network shares. It logs on to remote systems using the account of the active user in the affected system. It may also use pre-defined list of user names and passwords to gain access to other shared folders in the network.

Exploits

This worm takes advantage of the following Windows vulnerabilities to propagate:

  • Buffer Overflow in SQL Server 2000
  • IIS5/WEBDAV vulnerability
  • RPC DCOM buffer overflow vulnerability
  • LSASS buffer overrun vulnerability

For more information regarding these vulnerabilities, please refer to the following Microsoft Web pages:

It has the capability to detect the presence and then exploit the vulnerabilities used by the variants of the following malware:

  • BKDR_KUANG
  • WORM_MYDOOM
  • BKDR_NETDEVIL
  • BKDR_OPTIXPRO
  • BKDR_SUB7

Backdoor Routine

This worm also has backdoor capabilities. It comes with a built-in Internet Relay Chat (IRC) bot which allows it to connect to an IRC server. t then waits for commands from a remote user. Once connected, the remote user gains virtual control of the affected system. The remote user can then execute the following malicious actions:

  • Add/deletes hares in the host system
  • Capture image from webcam
  • Enable/disable DCOM in the host system
  • Gather cached passwords
  • Get clipboard data of the host system
  • List processes in host system
  • Performa Distributed Denial of Service (DDoS) attack
  • Perform FTP operations
  • Perform HTTP operations
  • Perform IRC operations
  • Perform port redirection
  • Scan for vulnerable and/or infected systems
  • Sendemailusingabuilt-in SMTP engine
  • Start/terminate processes in the host system
  • Start a network sniffer
  • Start keylogger

Information Theft

This worm steals the CD keys of the following PC games, if they are installed on the system:

  • Battlefield 1942
  • Battlefield 1942(RoadToRome)
  • Battlefield 1942(SecretWeaponsofWWII)
  • Battlefield Vietnam
  • Black and White
  • Chrome
  • Command and Conquer:Generals
  • Command and Conquer:Generals(ZeroHour)
  • Command and Conquer:RedAlert
  • Command and Conquer:RedAlert2
  • Command and Conquer:TiberianSun
  • Counter-Strike(Retail)
  • FIFA 2002
  • FIFA 2003
  • Freedom Force
  • Global Operations
  • Gunman Chronicles
  • Half-Life
  • Hidden & Dangerous2
  • IGI2:CovertStrike
  • Industry Giant 2
  • James Bond 007:Nightfire
  • Legends of Might and Magic
  • Medal of Honor:Allied Assault
  • Medal of Honor:Allied Assault:Breakthrough
  • Medal of Honor:Allied Assault:Spearhead
  • NHL 2002
  • NHL 2003
  • NOX
  • Nascar Racing 2002
  • Nascar Racing 2003
  • Need For Speed HotPursuit2
  • Need For Speed :Underground
  • Neverwinter Nights
  • Neverwinter Nights(HordesoftheUnderdark)
  • Neverwinter Nights(ShadowsofUndrentide)
  • Rainbow Six III RavenShield
  • Shogun:TotalWar: Warlord Edition
  • Soldier of Fortune II - Double Helix
  • Soldiers Of Anarchy
  • The Gladiators
  • Unreal Tournament 2003
  • Unreal Tournament 2004





Analysis by: Brian G. Cortes

Revision History:

First pattern file version: 2.348.04
First pattern file release date: Jan 14, 2005

SOLUTION


Minimum scan engine version needed: 6.810

Pattern file needed: 2.507.01

Pattern release date: Mar 21, 2005


Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.

Solution:

AUTOMATIC REMOVAL INSTRUCTIONS

To automatically remove this malware from your system, please use Trend Micro Damage Template / Engine.

MANUAL REMOVAL INSTRUCTIONS

Terminating the Malware Program

This procedure terminates the running malware process.

  1. Open Windows Task Manager.

  2. � On Windows 95, 98, and ME, press
    CTRL%20ALT%20DELETE
    � On Windows NT, 2000, and XP, press
    CTRL%20SHIFT%20ESC, then click the Processes tab.
  3. In the list of running programs*, locate the process:

  4. DEVSRV.EXE
  5. Select the malware process, then press either the End Task or the End Process button, depending on the version of Windows on your system.
  6. To check if the malware process has been terminated, close Task Manager, and then open it again.
  7. Close Task Manager.

*NOTE: On systems running Windows 95, 98, and ME, Windows Task Manager may not show certain processes. You can use a third party process viewer such as Process Explorer to terminate the malware process. Otherwise, continue with the next procedure, noting additional instructions.

Removing Autostart Entries from the Registry

Removing autostart entries from the registry prevents the malware from executing at startup.

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:

  3. HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>
    Windows>CurrentVersion>Run
  4. In the right panel, locate and delete the entry:

  5. Device Microsoft System = �DEVSRV.EXE�
  6. In the left panel, double-click the following:

  7. HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>
    Windows>CurrentVersion>RunServices
  8. In the right panel, locate and delete the entry:

  9. Device Microsoft System = �DEVSRV.EXE�
  10. In the left panel, double-click the following:

  11. HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>Run
  12. In the right panel, locate and delete the entry:

  13. Device Microsoft System = �DEVSRV.EXE�

NOTE: If you were not able to terminate the malware process as described in the previous procedure, restart your system.

Restoring Modified Registry Entries

  1. Still in the Registry Editor, in the left panel, double-click the following:

  2. HKEY_LOCAL_MACHINE>Software>Microsoft>OLE
  3. In the right panel, locate and modify the following registry entry from:

  4. EnableDCOM = �N� to
    EnableDCOM = �Y�
  5. Close Registry Editor.

Restoring EnableDCOM and RestrictAnonymous registry entries

This malware modifies EnableDCOM and RestrictAnonymous registry entries to a certain value. To know more about restoring these registries to their original values, please refer to these articles:

  1. COM security frequently asked questions
  2. How to disable DCOM support in Windows
  3. How to Use the RestrictAnonymous Registry Value in Windows 2000
  4. The "RestrictAnonymous" Registry Value May Break the Trust to a Windows 2000 Domain

Additional Windows ME/XP Cleaning Instructions

Users running Windows ME and XP must disable System Restore to allow full scanning of infected systems.

Users running other Windows versions can proceed with the succeeding procedure sets.

Running Trend Micro Antivirus

Scan your system with Trend Micro antivirus and delete all files detected as WORM_RBOT.AHL. To do this, Trend Micro customers must download the latest pattern file and scan their system. Other Internet users can use HouseCall, Trend Micro�s online virus scanner.

Applying Patches

This malware exploits known vulnerabilities in Microsoft Windows. Download and install the following fix patches supplied by Microsoft:

Trend Micro advises users to download critical patches upon release by vendors.




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