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BKDR_HAMMERTOSS.A

August 02, 2015
 Analysis by: Francis Xavier Antazo
 ALIASES:

Backdoor.Netduke (Symantec)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet


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:

50688 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Apr 2015

Payload:

Connects to URLs/IPs

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 adds the following processes:

  • iexplore.exe

NOTES:

It connects to the following URL to monitor the malicious user's generated account's activity:

  • twitter.com

It only runs after the date April, 3, 2015.

It does not run on the following days of the week:

  • Saturday
  • Sunday

It uses Domain Generation Algorithm (DGA) to generate URLs for the malicious user.

If active, it searches for the tweet that contains the link to the file it downloads. The file it downloads is usually a malicious image file that contains an encrypted data

It decrypts the said data and execute the decrypted code.

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.822.03

FIRST VSAPI PATTERN DATE:

30 Jul 2015

VSAPI OPR PATTERN File:

11.823.00

VSAPI OPR PATTERN Date:

31 Jul 2015

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 to delete files detected as BKDR_HAMMERTOSS.A. 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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