Malware type: Worm

Aliases: Backdoor.Win32.Rbot.gen (Kaspersky), W32/Sdbot.worm.gen.bz (McAfee), W32.Spybot.Worm (Symantec), TR/Downloader.Gen (Avira), W32/Rbot-Fam (Sophos),

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:


Distribution potential:


This memory-resident worm is another variant of the RBOT family that exploits the vulnerabilities discussed in the following pages:

This worm propagates through network shares, and drops a copy of itself as the file F0MERED.EXE in the Windows system folder. It uses a list of user names and passwords to gain access to shared folders.

It acts as a server program controlled by an Internet Relay Chat (IRC) bot, thus capable of certain backdoor activities. It is also capable of stealing the CD keys of certain applications.

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

For additional information about this threat, see:

Description created: Nov. 23, 2004 12:59:47 PM GMT -0800


Size of malware: 71,945 Bytes

Initial samples received on: Nov 23, 2004

Payload 1: Steals CD keys

Payload 2: Compromises system security


Upon execution, this memory-resident worm drops a copy of itself as the file F0MERED.EXE in the Windows system folder.

It creates the following registry entries to ensure its automatic execution at every Windows startup:

Start aThx Roll = "f0mered.exe"

Start aThx Roll = "f0mered.exe"

Start aThx Roll = "f0mered.exe"

It also modifies the following registry entries:

EnableDCOM = "Y"

Restrictanonymous = "dword(00000000)"

These entries are modified to (respectively):

EnableDCOM = "N"

Restrictanonymous = "dword(00000001)"

Network Propagation

This worm spreads through network shares. It searches the network for the following shared folders:

  • ADMIN$\System32
  • C$\Windows\system32
  • C$\WINNT\system32

This worm attempts to drop a copy of itself into these shares. If these shared folders have restricted access rights, this worm uses a hardcoded list of common user names and passwords to drop its copy.

Microsoft Windows Exploits

This worm uses the following vulnerabilities to propagate through the network:

  • Buffer Overflow in SQL Server 2000, which is a vulnerability that allows a low-level user to run, delete, insert or update Web tasks. In turn, an attacker who is able to authenticate to a SQL server may do the same actions, and run already created Web tasks in the context of the creator of that task. More information on this vulnerability is found in Microsoft Security Bulletin MS02-061.

  • The RPC/DCOM vulnerability, which is a vulnerability that allows an attacker to gain full access and execute any code on a target machine by sending a malformed packet to the DCOM service. It uses the RPC TCP port 135. More information on this vulnerability is found in Microsoft Security Bulletin MS03-026.

  • The Windows LSASS vulnerability, which is a buffer overrun that allows remote code execution and enables a malicious user to gain full control of the affected system. This vulnerability is discussed in detail in Microsoft Security Bulletin MS04-011 and Trend Micro's Vulnerability Description for MS04-011.

Backdoor Routines

This worm comes with a built-in Internet Relay Chat (IRC) client, which allows it to connect to an IRC channel. It opens a random port and waits for commands from a remote user. It is capable of doing certain commands, including the following:

  • Perform basic IRC commands
  • Perform basic FTP commands
  • Perform basic HTTP commands
  • Perform a distributed denial of service (DDoS) attack
  • Perform port redirection
  • Perform packet sniffing
  • Execute/list/terminate processes
  • download or search for files
  • Set up a proxy server
  • Get system and network information
  • Get Windows login password
  • List/start/stop a service
  • Send email
  • Create/list/delete user accounts
  • Add/delete/list network shares
  • Enable/disable DCOM
  • Enable/disable anonymous logon
  • Flush DNS cache
  • Perform keylogging routine
  • Capture webcam video
  • Gather cached passwords
  • Scan for vulnerable and/or infected systems

Information Theft

This worm is capable of obtaining the Microsoft Product ID and CD keys of the following games:

  • Battlefield 1942
  • Battlefield 1942 (Road To Rome)
  • Battlefield 1942 (Secret Weapons of WWII)
  • Battlefield Vietnam
  • Black and White
  • Chrome
  • Command and Conquer: Generals
  • Command and Conquer: Generals (Zero Hour)
  • Command and Conquer: Red Alert
  • Command and Conquer: Red Alert 2
  • Command and Conquer: Tiberian Sun
  • Counter-Strike (Retail)
  • FIFA 2002
  • FIFA 2003
  • Freedom Force
  • Global Operations
  • Gunman Chronicles
  • Half-Life
  • Hidden & Dangerous 2
  • IGI 2: Covert Strike
  • 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
  • Nascar Racing 2002
  • Nascar Racing 2003
  • Need For Speed Hot Pursuit 2
  • Need For Speed: Underground
  • Neverwinter Nights
  • Neverwinter Nights (Hordes of the Underdark)
  • Neverwinter Nights (Shadows of Undrentide)
  • NHL 2002
  • NHL 2003
  • NOX
  • Rainbow Six III RavenShield
  • Shogun: Total War: Warlord Edition
  • Soldier of Fortune II - Double Helix
  • Soldiers Of Anarchy
  • The Gladiators
  • Unreal Tournament 2003
  • Unreal Tournament 2004

Analysis by: Marc Sison

Revision History:

First pattern file version: 7.631.00
First pattern file release date: Nov 17, 2010


Minimum scan engine version needed: 6.810

Pattern file needed: 7.631.00

Pattern release date: Nov 17, 2010

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.


Terminating the Malware Program

This procedure terminates the running malware process.

  1. Open Windows Task Manager.
    On Windows 95, 98, and ME, press
    On Windows NT, 2000, and XP, press
    CTRL%20SHIFT%20ESC, then click the Processes tab.
  2. In the list of running programs*, locate the process:
  3. Select the malware process, then press either the End Task or the End Process button, depending on the version of Windows on your system.
  4. To check if the malware process has been terminated, close Task Manager, and then open it again.
  5. 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. In the right panel, locate and delete the entry:
    Start aThx Roll = "f0mered.exe"
  4. In the left panel, double-click the following:
  5. In the right panel, locate and delete the entry:
    Start aThx Roll = "f0mered.exe"
  6. In the left panel, double-click the following:
  7. In the right panel, locate and delete the entry:
    Start aThx Roll = "f0mered.exe"

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

Restoring Registry Default Values

Since this malware also modifies your default registry entries, you must also change these malware settings to the correct settings.

  1. Still in the Registry Editor, in the left panel, locate the key:
  2. In the right panel, locate the entry:
    EnableDCOM = "N"
  3. Right-click on this registry entry and choose Modify. Change the value of this entry to:
    EnableDCOM = "Y"
  4. 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.AAV. 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. Download and install the following patches to secure your system:

Refrain from using your Microsoft product until the appropriate patch has been installed. Trend Micro advises users to download critical patches upon release by vendors.critical patches upon release by vendors.

Trend Micro offers best-of-breed antivirus and content-security solutions for your corporate network, small and medium business, mobile device or home PC.