Analysis by: Mark Joseph Manahan
 ALIASES:

(Win32/TrojanDownloader.VB.PVA trojan (Eset), Trojan:Win32/Malagent (Microsoft), W32/Injector.FFNX!tr (Fortinet)

 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:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor 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

Tipo de compactação: 30,208 bytes
Tipo de arquivo: EXE
Residente na memória: Yes
Data de recebimento das amostras iniciais: 27 Jun 2012

Arrival Details

This backdoor 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 backdoor drops the following copies of itself into the affected system:

  • %User Profile%\chrome.exe
  • %User Profile%\My Documents\chrome.exe
  • %User Startup%\chrome.exe
  • %Desktop%\chrome.exe
  • %User Profile%\Downloads\chrome.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.. %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.. %Desktop% is the current user's desktop, which is usually C:\Documents and Settings\{User Name}\Desktop on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\Desktop on Windows Vista and 7.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
a = "%Desktop%\chrome.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
b = "%User Profile%\My Documents\chrome.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
c = "%User Profile%\Downloads\chrome.exe"

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

Other Details

This backdoor connects to the following possibly malicious URL:

  • {BLOCKED}1.hopto.org