Analysis by: RonJay Kristoffer Caragay
ALIASES:

TrojanDownloader:Win32/Small.gen!K (Microsoft), Trojan-Downloader.Win32.Small(Sunbelt)

 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:
 INFORMATION EXPOSURE:

  • 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 the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 148,992 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Jul 2014
Payload: Connects to URLs/IPs, Downloads 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.

Download Routine

This Trojan connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}.{BLOCKED}.129.3/zpm.exe
  • http://{BLOCKED}.{BLOCKED}.129.3/bet.exe
  • http://{BLOCKED}.{BLOCKED}.129.3/ng.exe
  • http://{BLOCKED}.{BLOCKED}.129.3/bnew.exe
  • http://{BLOCKED}.{BLOCKED}.129.3/dqnew.exe

It saves the files it downloads using the following names:

  • %User Temp%\kutylds.exe - detected as WORM_NGRBOT.AZB
  • %User Temp%\yhtyrg.exe - detected as BKDR_NEUREVT.AZB
  • %User Temp%\kuytr.exe - detected as WORM_DORKBOT.AZB
  • %User Temp%\hjku.exe - detected as TROJ_LETHIC.AZB
  • %User Temp%\f3re.exe - detected as TROJ_LETHIC.AZB

(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.)

It then executes the downloaded files. As a result, malicious routines of the downloaded files are exhibited on the affected system.

  SOLUTION

Minimum Scan Engine: 9.700

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Remove malware/grayware files dropped/downloaded by TROJ_DLOAD.AZBR. (Note: Please skip this step if the threats listed below have already been removed.)

     
    • %User Temp%\Temp\kutylds.exe - WORM_NGRBOT.AZB
    • %User Temp%\yhtyrg.exe - BKDR_NEUREVT.AZB
    • %User Temp%\kuytr.exe - WORM_DORKBOT.AZB
    • %User Temp%\hjku.exe - TROJ_LETHIC.AZB
    • %User Temp%\f3re.exe - TROJ_LETHIC.AZB

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_DLOAD.AZBR. 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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