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BKDR_SMALLDOO.CS

November 25, 2014
 ALIASES:

ARC:NSIS, PAK:[$TEMP\~DFDB$R10.TMP]:ASPack (Kaspersky); AdaEbook (v) (not malicious) (Sunbelt)

 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:

3,160,356 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

26 May 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.

Other System Modifications

This backdoor deletes the following files:

  • %User Temp%\nsw1.tmp

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\{E8CFC029-8420-4EAE-ADEF-915BDC77E1DC}

HKEY_CLASSES_ROOT\CLSID\{E8CFC029-8420-4EAE-ADEF-915BDC77E1DC}\
LocalServer32

HKEY_CLASSES_ROOT\~DFDB1014.MyNSHandler

HKEY_CLASSES_ROOT\~DFDB1014.MyNSHandler\Clsid

HKEY_CLASSES_ROOT\CLSID\{E8CFC029-8420-4EAE-ADEF-915BDC77E1DC}\
ProgID

Dropping Routine

This backdoor drops the following files:

  • %User Temp%\~DFDB1014.TMP

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

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_CLASSES_ROOT\CLSID
    • {E8CFC029-8420-4EAE-ADEF-915BDC77E1DC}
  • In HKEY_CLASSES_ROOT\CLSID\{E8CFC029-8420-4EAE-ADEF-915BDC77E1DC}
    • LocalServer32
  • In HKEY_CLASSES_ROOT
    • ~DFDB1014.MyNSHandler
  • In HKEY_CLASSES_ROOT\~DFDB1014.MyNSHandler
    • Clsid
  • In HKEY_CLASSES_ROOT\CLSID\{E8CFC029-8420-4EAE-ADEF-915BDC77E1DC}
    • ProgID

Step 3

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.
  • %User Temp%\~DFDB1014.TMP

Step 4

Scan your computer with your Trend Micro product to delete files detected as BKDR_SMALLDOO.CS. 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 5

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.

  • %User Temp%\nsw1.tmp


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