TROJ_DROPPR.YYNH

February 10, 2015
 ALIASES:

Worm:Win32/Dorkbot.I (Microsoft); ERROR (Kaspersky); Trojan horse BackDoor.Generic17.BJMQ (AVG)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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 deletes itself after execution.

  TECHNICAL DETAILS

File Size:

191,488 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

10 Feb 2015

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:

  • %User Profile%\Application Data\temp.bin
  • %User Profile%\Application Data\ScreenSaverPro.scr
  • %User Profile%\Microsoft\Jrrarj.exe

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

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Screen Saver Pro 3.1 = "%User Profile%\Application Data\ScreenSaverPro.scr"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Jrrarj = "%User Profile%\Microsoft\Jrrarj.exe"

Other System Modifications

This Trojan modifies the following file(s):

  • %Windows%\wiadebug.log

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

It deletes the following files:

  • %User Profile%\Application Data\temp.bin
  • %User Profile%\Application Data\ScreenSaverPro.scr
  • %User Temp%\apiwipmania.com
  • %Windows%\SoftwareDistribution\DataStore\Logs\edbtmp.log

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Paint

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Paint\Recent File List

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Paint\Settings

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Paint\View

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Paint\Text

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Paint\Colors

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Paint\General-Summary

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://app.{BLOCKED}ia.net/icon/n.api
  • http://api.{BLOCKED}ia.com
  • {BLOCKED}0.1
  • {BLOCKED}.98.202

It deletes itself after execution.

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.700

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 Safe Mode

[ Learn More ]

Step 3

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.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets
    • Paint
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Paint
    • Recent File List
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Paint
    • Settings
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Paint
    • View
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Paint
    • Text
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Paint
    • Colors
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Paint
    • General-Summary

Step 4

Delete this registry value

[ 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.

  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Screen Saver Pro 3.1 = "%User Profile%\Application Data\ScreenSaverPro.scr"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Jrrarj = "%User Profile%\Microsoft\Jrrarj.exe"

Step 5

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

Step 6

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    • %Windows%\wiadebug.log

Step 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Profile%\Application Data\temp.bin
  • %User Profile%\Application Data\ScreenSaverPro.scr
  • %User Temp%\apiwipmania.com
  • %Windows%\SoftwareDistribution\DataStore\Logs\edbtmp.log


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