WORM_RBOT.AEH

Malware type: Worm

Aliases: Backdoor.Win32.Rbot.aeu (Kaspersky), W32/Sdbot.worm.gen.l (McAfee), W32.Randex.gen (Symantec), Worm/Rbot.106496.28 (Avira), W32/Rbot-Fam (Sophos), Backdoor:Win32/Rbot (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:

High

Description: 

This memory-resident worm takes advantage of the following Windows vulnerabilities to propagate across networks:

  • RPC/DCOM vulnerability
  • LSASS vulnerability

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

It is also capable of scanning network shares on random IP addresses. If a remote system has full access rights, this worm drops a copy of itself to the machine. Otherwise, it attempts to log on to the machine using a list of user names and passwords. It may also gather user names and passwords from the system cache.

This worm also has backdoor capabilities. It connects to an Internet Relay Chat (IRC) server, where it waits for malicious commands coming from a remote user. It executes the commands locally on an affected machine, providing the malicious user virtual control over the system.

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

For additional information about this threat, see:

Description created: Dec. 16, 2004 5:25:08 PM GMT -0800


TECHNICAL DETAILS


Size of malware: 99,840 Bytes

Initial samples received on: Dec 16, 2004

Payload 1: Performs backdoor routines

Details:

Installation and Autostart Techniques

Upon execution, this memory-resident worm drops a copy of itself in the Windows system folder as the file VSSTATMN32.EXE.

It creates the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Mcafee Antivirus Monitoring System32mn = "VSStatmn32.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\RunM
Mcafee Antivirus Monitoring System32mn = "VSStatmn32.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\RunServices
Mcafee Antivirus Monitoring System32mn = "VSStatmn32.exe"

Network Propagation and Exploits

This worm is capable of spreading across networks by taking advantage of the following Microsoft Windows vulnerabilities:

  • RPC/DCOM vulnerability
  • LSASS vulnerability

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

This worm is also capable of scanning network shares on random IP addresses. If a remote system has full access rights, this worm drops a copy of itself to the machine. Otherwise, it attempts to log on to the machine using a list of user names and passwords. It may also gather user names and passwords from the system cache.

If it is able to successfully drop a copy of itself, it attempts to use the Schedule service to automatically execute itself.

Backdoor Capabilities

This worm also has backdoor capabilities. It connects to an Internet Relay Chat (IRC) server, where it waits for malicious commands coming from a remote user. It executes the commands locally on an affected machine, providing the malicious user virtual control over the system.

It can perform the following activities:

  • Delete network shares
  • Download files
  • Enable/Disable DCOM
  • Execute, delete, rename, or find files
  • Get network information
  • Get system information
  • List and terminate threads
  • Perform distributed denial of service (DDoS) attacks
  • Perform several IRC-related functions
  • Reboot system
  • Restrict ICP share
  • Scan for vulnerable systems
  • Send file via DCC
  • Start HTTPD, SOCKS4, or TFTP server
  • Start remote command shell
  • Take screen or webcam captures
  • Update malware
  • Use Microsoft NET commands

Other Details

This worm arrives compressed using Morphine and UPX.




Analysis by: Dennis John Biel

Revision History:

First pattern file version: 2.305.00
First pattern file release date: Dec 16, 2004

SOLUTION


Minimum scan engine version needed: 7.500

Pattern file needed: 3.568.03

Pattern release date: Jul 13, 2006


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:

Terminating the Malware Program

This procedure terminates the running malware process.

  1. Open Windows Task Manager.
    � 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.
  2. In the list of running programs*, locate the process:
    VSStatmn32.exe
  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:
    HKEY_LOCAL_MACHINE>Software>Microsoft>
    Windows>CurrentVersion>Run
  3. In the right panel, locate and delete the entry:
    Mcafee Antivirus Monitoring System32mn = "VSStatmn32.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:
    Mcafee Antivirus Monitoring System32mn = "VSStatmn32.exe"
  6. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>Run
  7. In the right panel, locate and delete the entry:
    Mcafee Antivirus Monitoring System32mn = "VSStatmn32.exe"
  8. Close Registry Editor.

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

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 set(s).

Running Trend Micro Antivirus

Scan your system with Trend Micro antivirus and delete all files detected as WORM_RBOT.AEH. 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 Windows. Download and install the fix patch supplied by Microsoft in the following 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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