Threat Encyclopedia

TROJ_DLOADE.FBV

Publish date: September 10, 2013

ANALYSIS BY

Rhena Inocencio


ALIASES:

Trojan:Win32/Mevade.D (Microsoft), Trojan-Downloader.Win32.MultiDL.c (Kaspersky), Generic Downloader.z (McAfee)

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:
INFORMATION EXPOSURE:

  • Threat Type:Trojan

  • Destructiveness:No

  • Encrypted: No

  • In the wild: Yes

OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware


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 uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

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

TECHNICAL DETAILS

File Size:

163,328 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

02 Jul 2013

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 drops the following copies of itself into the affected system:

  • %System%\FlashPlayerUpdateService.exe
  • %System%\Macromed\Flash\FlashPlayerUpdateService.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\AdobeFlashPlayerUpdateSvc
Type = "20"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\AdobeFlashPlayerUpdateSvc
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\AdobeFlashPlayerUpdateSvc
ErrorControl = "1"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\AdobeFlashPlayerUpdateSvc
ImagePath = "%System%\Macromed\Flash\FlashPlayerUpdateService.exe"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\AdobeFlashPlayerUpdateSvc
DisplayName = "Adobe Flash Player Update Service"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\AdobeFlashPlayerUpdateSvc
ObjectName = "LocalSystem"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\AdobeFlashPlayerUpdateSvc
Description = "This service keeps your Adobe Flash Player installation up to date with the latest enhancements and security fixes."

It registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\AdobeFlashPlayerUpdateSvc

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_ADOBEFLASHPLAYERUPDATESVC

The scheduled task executes the malware at the following period:

  • %Windows%\Tasks\AdobeFlashPlayerUpdate.job - executes the malware daily every one hour
  • %Windows%\Tasks\AdobeFlashPlayerUpdate 2.job - executes the malware at system startup

(Note: %Windows% is the Windows folder, which is usually C:\Windows.)

Other System Modifications

This Trojan adds the following registry keys as part of its installation routine:

HKEY_LOCAL_MACHINE\SOFTWARE\AdobeFlashPlayerUpdate

Download Routine

This Trojan accesses the following websites to download files:

  • http://{BLOCKED}evaillancourt.sytes.net/attachments/tc.c1

It saves the files it downloads using the following names:

  • %User Temp%\{random number}.tmp - BKDR_MEVADE.A

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

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

NOTES:

It accepts the following parameters:

  • /i - installs copies of itself into the system
  • /r - registers the dropped copy as a service
  • /w - downloads arbitrary file

SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

10.262.01

FIRST VSAPI PATTERN DATE:

06 Sep 2013

VSAPI OPR PATTERN File:

10.263.00

VSAPI OPR PATTERN Date:

07 Sep 2013

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 malware/grayware files dropped/downloaded by TROJ_DLOADE.FBV

Step 3

Disable this malware service

[ Learn More ]
  • AdobeFlashPlayerUpdateSvc

Step 4

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • AdobeFlashPlayerUpdateSvc
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root
    • LEGACY_ADOBEFLASHPLAYERUPDATESVC

Step 5

Search and delete these files

[ Learn More ]
There may be some component files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden files and folders in the search result.
  • %Windows%\Tasks\AdobeFlashPlayerUpdate.job
  • %Windows%\Tasks\AdobeFlashPlayerUpdate 2.job

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_DLOADE.FBV. 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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