Threat Encyclopedia

TROJ_FLASHUP.B

Publish date: July 08, 2015

ANALYSIS BY

Cris Nowell Pantanilla


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


The malicious files <i>flash32.exe</i> and <i>kbflashUpd.dll</i> are detected as TROJ_FLASHUP.A and TROJ_FLASHUP.B, respectively. These are the downloaded payloads of TROJ_NETISON.AB. The malware TROJ_NETISON.AB is the payload from the Adobe Flash zero-day vulnerability CVE-2015-5119.

To get a one-glance comprehensive view of the behavior of this Trojan, refer to the Threat Diagram shown below.

This Trojan may arrive bundled with malware packages as a malware component. It may be downloaded by other malware/grayware from remote sites.

It connects to certain websites to send and receive information.

TECHNICAL DETAILS

File Size:

129,536 bytes

File Type:

DLL

Memory Resident:

Yes

Initial Samples Received Date:

07 Jul 2015

Payload:

Connects to URLs/IPs

Arrival Details

This Trojan may arrive bundled with malware packages as a malware component.

It may be downloaded by the following malware/grayware from remote sites:

  • TROJ_NETISON.AB

Installation

This Trojan adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Windows Update System Verifier

It is injected into the following processes running in memory:

  • dwm.exe
  • wuauclt.exe
  • ctfmon.exe
  • wscntfy.exe

It terminates itself if it finds the following processes in the affected system's memory:

  • regmon.exe
  • filemon.exe
  • procMon.exe

Other Details

This Trojan connects to the following URL(s) to check for an Internet connection:

  • www.update.microsoft.com

It connects to the following website to send and receive information:

  • http://{BLOCKED}esstea.com/page2/oneclick.php?max-width={value}
  • http://{BLOCKED}esstea.com/page2/oneclick.php?ads_id={value}&rparam={encrypted data}-{Computer Name}-{Version}-{encrypted data}
  • http://{BLOCKED}esstea.com/page2/oneclick.php?cat_id={value}

NOTES:

This DLL file is executed by TROJ_FLASHUP.A

This Trojan searches for the following files and executes them if it exists:

  • %Application Data%\microsoft\common\iecache32.exe
  • %Application Data%\microsoft\common\iecookie.exe
  • %Application Data%\microsoft\common\upx32.dll
  • %Application Data%\microsoft\common\dllhosts.exe

It searches files in the folder %Application Data%\adobe\reader\temp. If files exists, it encrypts the file and sends it to the site http://{BLOCKED}esstea.com/page2/oneclick.php?cat_id={value}. It then deletes the file afterwards.

It creates the following processes and injects flash32.exe:

  • %System%\cipher.exe
  • %System%\gpupdate.exe
  • %System%\services.exe
  • %System%\sppsvc.exe
  • %System%\winrshost.exe

SOLUTION

Minimum Scan Engine:

9.750

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

Remove the malware/grayware file dropped/downloaded by TROJ_FLASHUP.B. (Note: Please skip this step if the threat(s) listed below have already been removed.)

     
    • TROJ_NETISON.AB

Step 3

Scan your computer with your Trend Micro product to delete files detected as TROJ_FLASHUP.B. 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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