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TROJ_DROPPR.SMAH

May 10, 2013
 ALIASES:

TrojanDownloader:Win32/Monkif.O (Microsoft); Downloader.a!gt (McAfee); Trojan Horse (Symantec); PAK:UPX (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.5374323 (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 deletes itself after execution.

  TECHNICAL DETAILS

File Size:

21,528 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

16 Jul 2012

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.

Other System Modifications

This Trojan deletes the following files:

  • %Windows%\default32.dll
  • %User Temp%\2.tmp
  • %User Temp%\3.tmp

(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Classes\
PROTOCOLS\Filter\text/html

HKEY_CURRENT_USER\Software\Classes\
CLSID\{90a7c2d2-7748-49da-8ca2-174c4a4883c1}\InProcServer32

It adds the following registry entries:

HKEY_CURRENT_USER\PROTOCOLS\Filter\
text/html
CLSID = "{90a7c2d2-7748-49da-8ca2-174c4a4883c1}"

HKEY_CURRENT_USER\CLSID\{90a7c2d2-7748-49da-8ca2-174c4a4883c1}\
InProcServer32
ThreadingModel = "Apartment"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\1.tmp
  • %Windows%\default32.dll

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Windows% is the Windows folder, which is usually C:\Windows.)

Other Details

This Trojan deletes itself after execution.

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 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\Classes\PROTOCOLS\Filter
    • text/html
  • In HKEY_CURRENT_USER\Software\Classes\CLSID\{90a7c2d2-7748-49da-8ca2-174c4a4883c1}
    • InProcServer32

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_CURRENT_USER\PROTOCOLS\Filter\text/html
    • CLSID = "{90a7c2d2-7748-49da-8ca2-174c4a4883c1}"
  • In HKEY_CURRENT_USER\CLSID\{90a7c2d2-7748-49da-8ca2-174c4a4883c1}\InProcServer32
    • ThreadingModel = "Apartment"

Step 4

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.
  • %User Temp%\1.tmp
  • %Windows%\default32.dll

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPR.SMAH. 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 6

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %Windows%\default32.dll
  • %User Temp%\2.tmp
  • %User Temp%\3.tmp


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