ALIASES:

TrojanDownloader:Win32/Dofoil.D (Microsoft); Generic Downloader.fn (McAfee); Downloader.Chepvil (Symantec); Trojan-Downloader.Win32.Injecter.gvw (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.KDV.371327 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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.

  TECHNICAL DETAILS

File Size: 38,912 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 10 Nov 2011

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 creates the following folders:

  • %User Profile%\Protect\

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
syyb = "rundll32 %User Profile%\Protect\ylcol.ll, oofg"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Sft

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\1.tmp
  • %User Temp%\2.tmp
  • %User Profile%\Protect\ylcol.ll
  • %User Startup%\dxdiag.exe

(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.. %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}.61.25/blog/load.php?module=grabbers
  • http://{BLOCKED}.61.25/blog/load.php?module=avclean
  • http://{BLOCKED}.61.25/blog/load.php?module=sniffers
  • http://{BLOCKED}onfly2006.ru/blog/grabbers.php
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2006.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://{BLOCKED}onfly2007.ru/blog/task.php?{random characters}
  • http://www.{BLOCKED}iba.jp/cbbs/sis.exe
  • http://www.{BLOCKED}iba.jp/cbbs/wweew.exe

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

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_LOCAL_MACHINE\Software\Microsoft
    • Sft

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • syyb = "rundll32 %User Profile%\Protect\ylcol.ll, oofg"

Step 5

Search and delete this folder

[ 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.
  • %User Profile%\Protect\

Step 6

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.
  • %User Temp%\1.tmp
  • %User Temp%\2.tmp
  • %User Profile%\Protect\ylcol.ll
  • %User Startup%\dxdiag.exe

Step 7

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