Analysis by: Anthony Joe Melgarejo
ALIASES:

Mal/Weelsof-E (Sophos), W32/DOFOIL.LF!tr (Fortinet)

 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: 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.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size: 49,152 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 06 Jun 2013

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.

Installation

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

  • %AppDataLocal%\{random file name}.exe

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

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://{BLOCKED}115.195:8080/{generated value}
  • http://{BLOCKED}115.200:8080/{generated value}
  • http://{BLOCKED}115.206:8080/{generated value}
  • http://{BLOCKED}115.208:8080/{generated value}
  • http://{BLOCKED}115.209:8080/{generated value}
  • http://{BLOCKED}115.213:8080/{generated value}
  • http://{BLOCKED}115.214:8080/{generated value}
  • http://{BLOCKED}115.215:8080/{generated value}
  • http://{BLOCKED}115.216:8080/{generated value}
  • http://{BLOCKED}84.62:8080/{generated value}
  • http://{BLOCKED}60.132:8080/{generated value}
  • http://{BLOCKED}.208.38:8080/{generated value}
  • http://{BLOCKED}.94.10:8080/{generated value}
  • http://{BLOCKED}43.133:8080/{generated value}
  • http://{BLOCKED}.32.166:8080/{generated value}
  • http://{BLOCKED}.180.144:8080/{generated value}
  • http://{BLOCKED}.17.146:8090/{generated value}
  • http://{BLOCKED}32.156:8080/{generated value}
  • http://{BLOCKED}.162.72:8080/{generated value}
  • http://{BLOCKED}.162.73:8080/{generated value}
  • http://{BLOCKED}.162.79:8080/{generated value}
  • http://{BLOCKED}.76.137:8080/{generated value}
  • http://{BLOCKED}.27.26:8080/{generated value}
  • http://{BLOCKED}.139.235:8080/{generated value}
  • http://{BLOCKED}.238.36:8080/{generated value}
  • http://{BLOCKED}.219.122:8080/{generated value}
  • http://{BLOCKED}.12.83:8080/{generated value}
  • http://{BLOCKED}.28.188:8080/{generated value}
  • http://{BLOCKED}3.108.86:8080/{generated value}
  • http://{BLOCKED}2.27.239:8080/{generated value}
  • http://{BLOCKED}.207.41:8080/{generated value}
  • http://{BLOCKED}0.162.42:8080/{generated value}
  • http://{BLOCKED}5.132.29:8080/{generated value}
  • http://{BLOCKED}.128.254:8090/{generated value}
  • http://{BLOCKED}.5.229:8080/{generated value}
  • http://{BLOCKED}253.250:8080/{generated value}

It deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine: 9.300

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

Scan your computer with your Trend Micro product and note files detected as BKDR_KULUOZ.USR

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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

Scan your computer with your Trend Micro product to delete files detected as BKDR_KULUOZ.USR. 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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