TROJ_BROXY.A

January 07, 2015
 Analysis by: Michael John Marcos
 ALIASES:

Trojan:Win32/Dynamer!dtc (Microsoft), Trojan.Win32.Genome.ajauu (Kaspersky)

 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:

Dropped by other malware

This Trojan may be dropped by other malware. It arrives as a component bundled with malware/grayware packages.

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

  TECHNICAL DETAILS

File Size:

14,848 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

29 Nov 2012

Payload:

Connects to URLs/IPs, Downloads files

Arrival Details

This Trojan may be dropped by other malware.

It arrives as a component bundled with malware/grayware packages.

Download Routine

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

  • http://{BLOCKED}gas.com
  • http://{BLOCKED}mahha.com
  • http://{BLOCKED}rikono.com
  • http://{BLOCKED}erts.com

It saves the files it downloads using the following names:

  • %Temp%\{random filename}.exe

(Note: %Temp% is the Windows temporary folder, where it usually is C:\Windows\Temp on all Windows operating system versions.)

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

NOTES:

This trojan attempts to download the file in the malicious URLs every 60 seconds.

The following is the template of the data it sends using HTTP GET:

GET favicon.ico
HTTP/1.1
Host: bcProxyBot.com
Accept: image/gif, image/x-xbitmap, image/jpeg,
image/pjpeg
Accept-Language: en-us
UA-CPU: x86
User-Agent: Mozilla/4.0 (compatible; MSIE 7.0;Windows NT 5.1;NET CLR 2.0.3.5)
Cookie: {random value}{Computer Name}

When the Trojan downloads a file from the malicious URL to the user's system, tt constructs its packet header to make itself appear as a harmless JPEG file, when its is actually an executable file. It does this to avoid detection by the network firewall or system security applications.

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

9.560.02

FIRST VSAPI PATTERN DATE:

29 Nov 2012

VSAPI OPR PATTERN File:

9.561.00

VSAPI OPR PATTERN Date:

29 Nov 2012

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 TROJ_BROXY.A

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete files detected as TROJ_BROXY.A

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.

Step 5

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


Did this description help? Tell us how we did.