BKDR_FAKEMS.ZZXX

 Modified by: Joie Salvio

 ALIASES:

Trojan:Win32/Comisproc (Microsoft), a variant of Win32/Agent.TDQ (ESET), Trojan-Dropper.Win32.Agent.gonr (Kaspersky), Dropped:Trojan.Generic.6827920 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It executes commands from a remote malicious user, effectively compromising the affected system. However, as of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

17,408 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

04 Mar 2012

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Autostart Technique

This backdoor registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc
Type = "0x00000020"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc
Start = "0x00000002"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc
ImagePath = "%systemroot%\system32\svchost.exe -k netgroup"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc
ErrorControl = "0x00000001"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc
DisplayName = "TP AutoConnection Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc
Group = "netsvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc\Parameters
ServiceDll = "%systemroot%\system32\tpautosvc.dll"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc\Security
Security = {hex values}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc\Enum
0 = "Root\LEGACY_TPAUTOCONSVC\0000"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc\Enum
Count = "0x00000001"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc\Enum
NextInstance = "0x00000001"

It registers its dropped component as a system service to ensure its automatic execution at every system startup. It does this by creating the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc\Parameters

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\TPAutoConSvc\Security

Other System Modifications

This backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
netgroup = "TPAutoConSvc"

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Perform Remote Shell

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • gmail.{BLOCKED}ktw.com - using port 80 and 443

However, as of this writing, the said sites are inaccessible.

Dropping Routine

This backdoor drops the following files:

  • %System%\tpautosvc.dll

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.750.07

FIRST VSAPI PATTERN DATE:

02 Feb 2012

VSAPI OPR PATTERN File:

8.751.00

VSAPI OPR PATTERN Date:

02 Feb 2012

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\SvcHost
    • netgroup = "TPAutoConSvc"

Step 4

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • TPAutoConSvc

Step 5

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %System%\tpautosvc.dll

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_FAKEMS.ZZXX. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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