Analysis by: Cris Nowell Pantanilla
ALIASES:

Trojan.Win32.Inject.aansu (Kaspersky), TrojanDownloader:Win32/Terdot.A (Microsoft)

 PLATFORM:

Windows

 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

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. As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size: 245,760 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 15 Jul 2016
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.

Installation

This Trojan injects threads into the following normal process(es):

  • explorer.exe

Download Routine

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

  • https://{BLOCKED}cast.com/b2.bin
  • https://{BLOCKED}rcast.com/c2.bin
  • https://{BLOCKED}co2.com/b2.bin
  • https://{BLOCKED}co2.com/c2.bin
  • https://{BLOCKED}3.com/b2.bin
  • https://{BLOCKED}co3.com/c2.bin

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

As of this writing, the said sites are inaccessible.

  SOLUTION

Minimum Scan Engine: 9.800
FIRST VSAPI PATTERN FILE: 12.654.03
FIRST VSAPI PATTERN DATE: 15 Jul 2016
VSAPI OPR PATTERN File: 12.655.00
VSAPI OPR PATTERN Date: 16 Jul 2016

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

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