Analysis by: Anthony Joe Melgarejo
ALIASES:

Backdoor.Winnti.B (Symantec), W64/Winnti.P!tr.bdr (Fortinet), Backdoor.Win64.Winnti (VBA32)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

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 executes then deletes itself afterward.

It executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

  TECHNICAL DETAILS

File Size: 445,524 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 12 Apr 2013
Payload: Drops files

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 executes then deletes itself afterward.

Dropping Routine

This Trojan drops the following files:

  • %Application Data%\tmp{number}.tmp - detected as BKDR64_WINNTI.D

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

It executes the files it drops, prompting the affected system to exhibit the malicious routines they contain.

NOTES:

It executes the dropped file using the following command:

  • rundll32.exe {malware path and file name}, Install {malware file name}

  SOLUTION

Minimum Scan Engine: 9.300

Step 1

Scan your computer with your Trend Micro product to delete files detected as TROJ64_WINNTI.SM. 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 2

Remove the malware/grayware file dropped/downloaded by TROJ64_WINNTI.SM

    • BKDR64_WINNTI.D

Step 3

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


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