Analysis by: RonJay Kristoffer Caragay
ALIASES:

TrojanDownloader:Win32/Dofoil.T (Microsoft); Trojan.Win32.Sharik.ugh (Kaspersky); Trojan.Win32.Sharik (Ikarus); Trojan-Downloader.Win32.Dofoil (Sunbelt)

 PLATFORM:

Windows

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

  • 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: 57,856 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 27 Oct 2014

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:

  • %Application Data%\{random folder name}\{random file name}.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

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\Policies\
Explorer\Run
{random installed program name} = "%Application Data%\{random folder name}\{random file name}.exe"

Other Details

This Trojan connects to the following possibly malicious URL:

  • {BLOCKED}77.biz

NOTES:

This Trojan may connect to non-malicious URL http://www.msn.com. It connects to seemingly non-malicious URLs that are related to installed programs under the following registry entries:

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\Uninstall\{Installed Program}
HelpLink = "{url related to installed program}"

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\
CurrentVersion\Uninstall\{Installed Program}
URLInfoAbout = "{url related to installed program}"

  SOLUTION

Minimum Scan Engine: 9.700
FIRST VSAPI PATTERN FILE: 11.238.08
FIRST VSAPI PATTERN DATE: 27 Oct 2014
VSAPI OPR PATTERN File: 11.239.00
VSAPI OPR PATTERN Date: 27 Oct 2014

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

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\Policies\Explorer\Run
    • {random installed program name} = "%Application Data%\{random folder name}\{random file name}.exe"

Step 5

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