TROJ_MULTIDRP.AA

Malware type: Trojan

Aliases: Proxy-FBSR (McAfee), Trojan.Dropper (Symantec), Worm/SdBot.109141 (Avira), Troj/Ranck-BO (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:

Medium

Distribution potential:

Low

Description: 

This Trojan drops the following files in C:\WINNT\system32:

  • vvzxx.exe - detected by Trend Micro as BKDR_SDBOT.ZV
  • xcavadt.exe - detected as Trend Micro as BKDR_RANKY.ZV

(Note: If the said folder does not exist on a system, it creates one.)

It also drops the following file in the Windows system folder:

    asacsqgl.exe - also detected by Trend Micro as BKDR_SDBOT.ZV

It creates registry entries to ensure the automatic execution of the dropped files at every Windows startup.

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

For additional information about this threat, see:

Description created: Dec. 5, 2004 1:56:14 AM GMT -0800


TECHNICAL DETAILS


Size of malware: 109,141 Bytes (compressed)

Initial samples received on: Nov 23, 2004

Details:

Upon execution, this UPX-compressed Trojan drops the following files in C:\WINNT\system32:

  • vvzxx.exe - detected by Trend Micro as BKDR_SDBOT.ZV
  • xcavadt.exe - detected as Trend Micro as BKDR_RANKY.ZV

(Note: If the said folder does not exist on a system, it creates one.)

It also drops the following file in the Windows system folder:

    asacsqgl.exe - also detected by Trend Micro as BKDR_SDBOT.ZV

It creates the following registry entries to ensure the automatic execution of the dropped files at every Windows startup:

HKEY_CURRENT_USER\Software\Microsoft\Windows\
CurrentVersion\Run
asccacA = "asacsqgl.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\RunServices
asccacA = "asacsqgl.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\Run
asccacA = "asacsqgl.exe"

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\Run
Qffecdas = "c:\winnt\system32\vvzxx.exe"

It also adds the following registry entry:

HKEY_CURRENT_USER\Software\WinRAR SFX
<folder that this Trojan creates> = "C:\WINNT\SYSTEM32\"




Analysis by: Elda Dimakiling


SOLUTION


Minimum scan engine version needed: 6.810

Pattern file needed: 2.261.00

Pattern release date: Nov 23, 2004


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:

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 entries:
    asccacA = "asacsqgl.exe"
    Qffecdas = "c:\winnt\system32\vvzxx.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:
    asccacA= "asacsqgl.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:
    asccacA = "asacsqgl.exe"

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

Removing Other Malware Entries from the Registry

  1. Still in the Registry Editor, in the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>WinRAR SFX>
  2. In the right panel, locate and delete the entry:
    <folder that this Trojan creates> = "C:\WINNT\SYSTEM32\"
  3. If the subkey WinRAR SFX does not have any other entry after deleting the entry in the previous step, delete this subkey.
  4. Close Registry Editor.

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 TROJ_MULTIDRP.AA, BKDR_SDBOT.ZV, and BKDR_RANKY.ZV. 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.


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