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BKDR_ZEGOST.SMM

August 08, 2013
 ALIASES:

Backdoor:Win32/Agent.AXB (Microsoft); Generic BackDoor!czf (McAfee); Trojan.Gen.2 (Symantec); Backdoor.Win32.Agent.bsvf (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Dropped:Backdoor.Generic.397991 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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.

  TECHNICAL DETAILS

File Size:

129,536 bytes

File Type:

EXE

Initial Samples Received Date:

30 Sep 2011

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.

Other System Modifications

This backdoor deletes the following files:

  • %System Root%\Documents AND Settings\apple.bat
  • %System Root%\APPLED~1.AQQ
  • {malware path and file name}
  • %System Root%\appledel.bat

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services
Type = 12

HKEY_CLASSES_ROOT
.grp = "MSProgramGroup"

HKEY_CLASSES_ROOT
MSProgramGroup = "Microsoft Program Group"

HKEY_CLASSES_ROOT
MSProgramGroup\Shell\Open\Command = "%System%\grpconv.exe %1"

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\GrpConv
Log = "Init Application."

(Note: The default value data of the said registry entry is Uninit Application..)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\GrpConv
Log = "bdg: ..."

(Note: The default value data of the said registry entry is Uninit Application..)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\GrpConv
Log = "bdg: Done."

(Note: The default value data of the said registry entry is Uninit Application..)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\GrpConv
Log = "dros: ..."

(Note: The default value data of the said registry entry is Uninit Application..)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\GrpConv
Log = "dros: Renames."

(Note: The default value data of the said registry entry is Uninit Application..)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\GrpConv
Log = "dros: Copies."

(Note: The default value data of the said registry entry is Uninit Application..)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\GrpConv
Log = "dros: Deletes."

(Note: The default value data of the said registry entry is Uninit Application..)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\GrpConv
Log = "dros: Done."

(Note: The default value data of the said registry entry is Uninit Application..)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\GrpConv
Log = "Uninit Application."

(Note: The default value data of the said registry entry is Uninit Application..)

Dropping Routine

This backdoor drops the following files:

  • %System%\systeminf.inf
  • %System Root%\Documents AND Settings\apple.bat
  • %System%\Thumdb.dll
  • %System%\111061617.exe
  • appledel.bat

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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

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\SYSTEM\ControlSet001\Services
    • Type=12
  • In HKEY_CLASSES_ROOT
    • .grp="MSProgramGroup"
  • In HKEY_CLASSES_ROOT
    • MSProgramGroup="Microsoft Program Group"
  • In HKEY_CLASSES_ROOT
    • MSProgramGroup\Shell\Open\Command="%System%\grpconv.exe %1"

Step 3

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\GrpConv
    • From: Log="Init Application."
      To: Log=Uninit Application.
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\GrpConv
    • From: Log="bdg: ..."
      To: Log=Uninit Application.
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\GrpConv
    • From: Log="bdg: Done."
      To: Log=Uninit Application.
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\GrpConv
    • From: Log="dros: ..."
      To: Log=Uninit Application.
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\GrpConv
    • From: Log="dros: Renames."
      To: Log=Uninit Application.
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\GrpConv
    • From: Log="dros: Copies."
      To: Log=Uninit Application.
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\GrpConv
    • From: Log="dros: Deletes."
      To: Log=Uninit Application.
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\GrpConv
    • From: Log="dros: Done."
      To: Log=Uninit Application.
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\GrpConv
    • From: Log="Uninit Application."
      To: Log=Uninit Application.

Step 4

Search and delete these files

[ Learn More ]
There may be some component 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%\systeminf.inf
  • %System Root%\Documents AND Settings\apple.bat
  • %System%\Thumdb.dll
  • %System%\111061617.exe
  • appledel.bat

Step 5

Scan your computer with your Trend Micro product to delete files detected as BKDR_ZEGOST.SMM. 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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