WORM_RBOT.BWR

Malware type: Worm

Aliases: Backdoor.Win32.Nepoe.c (Kaspersky), W32/Sdbot.worm.gen.z (McAfee), W32.IRCBot (Symantec), Worm/RBot (Avira),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 95, 98, ME, NT, 2000, XP. Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

High

Description: 

This memory-resident worm drops a copy of itself as OFFICEGUI1.EXE in the Windows System folder. It then creates registry entries for its autostart routine.

This worm spreads through network shares by dropping copies of itself into particular default shares. It does this by using a list of user names and passwords to access these shares.

Also, it exploits the following Windows vulnerabilities to propagate across networks:

  • Buffer Overrun In RPCSS Service Could Allow Code Execution vulnerability
  • LSASS Remote Buffer Overflow

More information on these vulnerabilities are found in the following Web sites:

This worm also backdoor capabilities. It connects to an IRC (Internet Relay Chat) server and creates a backdoor bot to enable a remote user to execute malicious commands on the target systems.

It also performs various flood attacks.

For additional information about this threat, see:

Description created: Sep. 8, 2005 6:22:08 PM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: 96,768 Bytes (compressed); 240,128 Bytes (uncompressed)

Ports used: Random

Initial samples received on: Jul 25, 2005

Compression type: Morphine

Vulnerability used:  (MS04-011) Security Update for Microsoft Windows (835732), (MS03-039) Buffer Overrun In RPCSS Service Could Allow Code Execution

Payload 1: Compromises system security

Payload 2: Connects to an IRC server and listens for commands

Payload 3: Performs various DDoS attacks

Details:

Installation and Autostart Routine

Upon execution, this worm drops a copy of itself as OFFICEGUI1.EXE in the Windows System folder. It then creates the following registry entries to ensure its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\Run
MS Office1 Startup = "OfficeGUI1.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\Run
MS Office1 Startup = "OfficeGUI1.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
CurrentVersion\RunServices
MS Office1 Startup = "OfficeGUI1.exe"

Propagation Routine and Exploits

This worm spreads through network shares. It does this by dropping copies of itself in the following default shares:

  • ADMIN$
  • C$
  • IPC$

It uses cached user names and passwords to gain access to these shares. It also uses a long list of user names and passwords, apart from those it gathers.

This worm also exploits the following Windows vulnerabilities to propagate across networks:

  • Buffer Overrun In RPCSS Service Could Allow Code Execution vulnerability
  • LSASS Remote Buffer Overflow

More information on these vulnerabilities are found in the following Web sites:

Backdoor Capabilities

This worm connects to an IRC (Internet Relay Chat) server and creates a backdoor bot, enabling a remote user to execute the following malicious commands on the affected system:

Denial of Service Attack

The worm is capable of the following flood attacks:

Other Details

This worm affects systems running on Windows 95, 98, ME, NT, 2000, XP, and Server 2003.

Analysis By: Anne Leonor Garcia Marcos

Revision History:

First pattern file version: 4.164.09
First pattern file release date: Jan 06, 2007

SOLUTION


Minimum scan engine version needed: 6.810

Pattern file needed: 4.165.00

Pattern release date: Jan 7, 2007


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:

Identifying the Malware Program

To remove this malware, first identify the malware program.

  1. Scan your system with your Trend Micro antivirus product.
  2. NOTE the path and file name of all files detected as WORM_RBOT.BWR.

Trend Micro customers need to download the latest virus pattern file before scanning their system. Other users can use Housecall, Trend Micro's online virus scanner.

Terminating the Malware Program

This procedure terminates the running malware process. You will need the name(s) of the file(s) detected earlier.

If the process you are looking for is not in the list displayed by Task Manager, proceed to the succeeding solution set.

  1. Open Windows Task Manager.
    • On Windows 95, 98, and ME, press
    CTRL%20ALT%20DELETE
    • On Windows NT, 2000, XP, and Server 2003, press
    CTRL%20SHIFT%20ESC, then click the Processes tab.
  2. In the list of running programs*, locate the malware file(s) detected earlier.
  3. Select one of the detected files, then press either the End Task or the End Process button, depending on the version of Windows on your system.
  4. Do the same for all detected malware files in the list of running processes.
  5. To check if the malware process has been terminated, close Task Manager, and then open it again.
  6. 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. If you were not able to terminate the malware process as described in the previous procedure, restart your system.

Editing the Registry

This malware modifies the system's registry. Users affected by this malware may need to modify or delete specific registry keys or entries. For detailed information regarding registry editing, please refer to the following articles from Microsoft:

  1. HOW TO: Backup, Edit, and Restore the Registry in Windows 95, Windows 98, and Windows ME
  2. HOW TO: Backup, Edit, and Restore the Registry in Windows NT 4.0
  3. HOW TO: Backup, Edit, and Restore the Registry in Windows 2000
  4. HOW TO: Back Up, Edit, and Restore the Registry in Windows XP and 2003

Removing Autostart Entries from the Registry

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

If the registry entries below are not found, the malware may not have executed as of detection. If so, proceed to the succeeding solution set.

  1. Open Registry Editor. Click Start>Run, type REGEDIT, then press Enter.
  2. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>Run
  3. In the right panel, locate and delete the entry:
    MS Office1 Startup = "OfficeGUI1.exe"
  4. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft> Windows>CurrentVersion>RunServices
  5. In the right panel, locate and delete the entry:
    MS Office1 Startup = "OfficeGUI1.exe"
  6. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft> Windows>CurrentVersion>Run
  7. In the right panel, locate and delete the entry:
    MS Office1 Startup = "OfficeGUI1.exe"
  8. Close Registry Editor.

Important 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 set(s).

Running Trend Micro Antivirus

If you are currently running on safe mode, please restart your system normally before performing the following solution.

Scan your system with Trend Micro antivirus and delete files detected as WORM_RBOT.BWR. To do this, Trend Micro customers must download the latest virus 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 Windows. Download and install the fix patches provided by Microsoft from the following Web pages:

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




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