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TROJ_DELF.SMA

October 03, 2013
 ALIASES:

TrojanDropper:Win32/Malf.gen (Microsoft); Keylog-Spynet.gen.f (McAfee); Trojan-Dropper.Win32.Agent.bpxo (Kaspersky); Trojan.Generic.2369970 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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

It disables Task Manager, Registry Editor, and Folder Options.

  TECHNICAL DETAILS

File Size:

491,008 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Nov 2011

Arrival Details

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

Installation

This Trojan drops the following copies of itself into the affected system:

  • %System%\System386\System.exe

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

It creates the following folders:

  • %System%\System386\

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

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
surak = "%System%\System386\System.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
surak = "%System%\System386\System.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{T5TBB77L-4678-0MKC-421Q-14416031DYU6}
StubPath = "%System%\System386\System.exe Restart"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\victima1

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run

HKEY_LOCAL_MACHINE\Software\Microsoft\
Active Setup\Installed Components\{T5TBB77L-4678-0MKC-421Q-14416031DYU6}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\victima1
FileNameAtual = "{malware path and file name}"

HKEY_CURRENT_USER\Software\victima1
FirstExecution = "11/04/2011"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
surak = "%System%\System386\System.exe"

HKEY_CURRENT_USER\Software\victima1
ByPersist = "%System%\System386\System.exe|surak|surak|"

HKEY_CURRENT_USER\Software\victima1
FileName = "Dlzcs1JtFiFdifAOxfQDRfRiNiFaqWI50CbV2r4iNlwM+xuGOy+DzD"

HKEY_CURRENT_USER\Software\victima1
HKLM = "zBnP9vA"

HKEY_CURRENT_USER\Software\victima1
HKCU = "zBnP9vA"

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\Run
surak = "%System%\System386\System.exe"

It deletes the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Active Setup\Installed Components\{T5TBB77L-4678-0MKC-421Q-14416031DYU6}

Dropping Routine

This Trojan drops the following files:

  • %System%\System386\logs.dat
  • %System%\System386\plugin.dat

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

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

Restart in Safe Mode

[ Learn More ]

Step 3

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

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.

  • In HKEY_CURRENT_USER\SOFTWARE
    • victima1
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • Run
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • Run
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Active Setup\Installed Components
    • {T5TBB77L-4678-0MKC-421Q-14416031DYU6}

Step 5

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\CurrentVersion\Run
    • surak="%System%\System386\System.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • surak="%System%\System386\System.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Active Setup\Installed Components\{T5TBB77L-4678-0MKC-421Q-14416031DYU6}
    • StubPath="%System%\System386\System.exe Restart"
  • In HKEY_CURRENT_USER\Software\victima1
    • FileNameAtual="{malware path and file name}"
  • In HKEY_CURRENT_USER\Software\victima1
    • FirstExecution="11/04/2011"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • surak="%System%\System386\System.exe"
  • In HKEY_CURRENT_USER\Software\victima1
    • ByPersist="%System%\System386\System.exe|surak|surak|"
  • In HKEY_CURRENT_USER\Software\victima1
    • FileName="Dlzcs1JtFiFdifAOxfQDRfRiNiFaqWI50CbV2r4iNlwM+xuGOy+DzD"
  • In HKEY_CURRENT_USER\Software\victima1
    • HKLM="zBnP9vA"
  • In HKEY_CURRENT_USER\Software\victima1
    • HKCU="zBnP9vA"

Step 6

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result. %System%\System386\

Step 7

Search and delete these components

[ Learn More ]
There may be some components 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%\System386\logs.dat
  • %System%\System386\plugin.dat

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_DELF.SMA. 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.

Step 9

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_CURRENT_USER\Software\Microsoft\Active Setup\Installed Components
    • {T5TBB77L-4678-0MKC-421Q-14416031DYU6}


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