WORM_SDBOT.CBA

Malware type: Worm

Aliases: Backdoor.Win32.Rbot.ss (Kaspersky), W32/Sdbot.worm.gen.g (McAfee), W32.Spybot.Worm (Symantec), TR/Downloader.Gen (Avira),

In the wild: Yes

Destructive: Yes

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 propagates through network shares. Upon execution, it drops a copy of itself as the file WINDOS.EXE in the Windows system folder. It then attempts to place copies of itself into accessible shared folders across a network.

It attempts 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 vulnerabilities to propagate:

  • RPCSS vulnerability
  • LSASS buffer overrun vulnerability

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

This worm has backdoor capabilities. It enables a remote user to perform malicious commands on the affected machine. The said routine provides remote users virtual control over affected systems, thus compromising system security.

It is capable of executing a number of different distributed denial of service (DDoS) attacks on target web sites.

For additional information about this threat, see:

Description created: Jul. 21, 2005 9:39:15 AM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: 161,792 Bytes

Initial samples received on: Jul 19, 2005

Compression type: ASProtect

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

Trigger condition 1: Upon execution

Payload 2: Performs various DDoS attacks

Trigger condition 1: Upon execution

Payload 3: Deletes shared folders

Trigger condition 1: Upon command from remote user

Payload 4: Steals information

Trigger condition 1: Upon command from remote user

Details:

Installation and Autostart Technique

This memory-resident worm propagates through network shares. Upon execution, it drops a copy of itself as the file WINDOS.EXE in the Windows system folder.

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

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\Run
Antivirus Update Check = "windos.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\RunServices
Antivirus Update Check = "windos.exe"

HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\Run
Antivirus Update Check = "windos.exe"

HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\RunServices
Antivirus Update Check = "windos.exe"

It also adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\OLE
Antivirus Update Check = "windos.exe"

HKEY_CURRENT_USER\System\CurrentControlSet\
Control\Lsa
Antivirus Update Check = "windos.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\OLE
Antivirus Update Check = "windos.exe"

HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Control\Lsa
Antivirus Update Check = "windos.exe"

Propagation via Network Shares

It attempts to drop a copy of itself into the following default shared folders:

  • ADMIN$
  • ADMIN$\DOCUME~1
  • ADMIN$\system32
  • C$\DOCUME~1\ADMINI~1
  • C$\Windows\system32
  • C$\WINNT\system32
  • D$\Windows\system32
  • D$\WINNT\system32
  • E$\Windows\system32
  • E$\WINNT\system32
  • IPC$
  • PRINTS$

It uses the following list of user names and passwords to log on to restricted shares:

Exploits

This worm takes advantage of the following vulnerabilities to propagate:

  • RPCSS vulnerability
  • LSASS buffer overrun vulnerability

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

Backdoor Capabilities

This worm has backdoor capabilities. It connects to an Internet Relay Chat (IRC) server using a random port. Once a connection is established, it joins an IRC channel, where it listens for commands coming from a remote malicious user. Some of these commands are as follows:

  • Download and execute files
  • Update the malware copy
  • Log keystrokes
  • Steal system information
  • Join and leave IRC channel
  • Scan for Ports
  • Steal clipboard contents
  • Create remote shell
  • Flush DNS Cache
  • List, start, or terminate processes
  • Visit URLs
  • Search for files
  • Delete network shares
  • Monitor the system registry

Denial of Service Attack

Denial of service (DoS) attacks disrupt the normal functions of a targeted Web site or group of Web sites, creates massive network traffic, and taxes IT infrastructure and resources. DoS attacks typically flood Web sites or servers with requests that may slow down or even crash the target site altogether. Having multiple computers attacking a single site constitute a distributed denial of service (DDoS) attack.

This worm enables malicious users to launch the following types of DDoS attacks against a target site:

  • DDoS flood attack
  • ICMP flood attack
  • Ping flood attack
  • SYN flood attack
  • TCP flood attack
  • UDP flood attack

Other Details

This worm runs on Windows 95, 98, ME, 2000, and XP.

Analysis By: James Patrick Dee

Revision History:

 

Jul 23, 2005 - Insertion of Automatic Removal Instructions

SOLUTION


Minimum scan engine version needed: 6.810

Pattern file needed: 2.738.01

Pattern release date: Jul 20, 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

MANUAL REMOVAL INSTRUCTIONS

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:
    WINDOS.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. 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_LOCAL_MACHINE>Software>Microsoft>
    Windows>CurrentVersion>Run
  3. In the right panel, locate and delete the entry:
    Antivirus Update Check = "windos.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:
    Antivirus Update Check = "windos.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:
    Antivirus Update Check = "windos.exe"
  8. In the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>RunServices
  9. In the right panel, locate and delete the entry:
    Antivirus Update Check = "windos.exe"

Removing Other Registry Entries

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

  2. HKEY_CURRENT_USER>Software>Microsoft>OLE
  3. In the right panel, locate and delete the entry:
  4. Antivirus Update Check = "windos.exe"
  5. In the left panel, double-click the following:
    HKEY_CURRENT_USER>System>CurrentControlSet>
    Control>Lsa
  6. In the right panel, locate and delete the entry:
    Antivirus Update Check = "windos.exe"
  7. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>Software>Microsoft>OLE
  8. In the right panel, locate and delete the entry:
  9. Antivirus Update Check = "windos.exe"
  10. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>System>CurrentControlSet>
    Control>Lsa
  11. In the right panel, locate and delete the entry:
    Antivirus Update Check = "windos.exe"
  12. 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

Scan your system with Trend Micro antivirus and delete files detected as WORM_SDBOT.CBA. 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 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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