Analysis by: Rika Joi Gregorio
ALIASES:

W32/Zbot.AAO!tr(Fortinet), a variant of Win32/Kryptik.BFPC trojan(Eset)

 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: 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: 408,064 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 12 Jul 2013

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:

  • %All Users Profile%\faedacacbac.exe

(Note: %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in Windows Vista and 7.)

It drops the following files:

  • %All Users Profile%\faedacacbac.cfg
  • %All Users Profile%\hosixvxyctqbdiv
  • {malware path}\libnspr4.dll

(Note: %All Users Profile% is the All Users or Common profile folder, which is C:\Documents and Settings\All Users in Windows 2000, XP, and Server 2003, and C:\ProgramData in 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
faedacacbac = ""%All Users Profile%\faedacacbac.exe""

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CLASSES_ROOT\.key

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.key

HKEY_CURRENT_USER\Software\faedacacbac

It adds the following registry entries:

HKEY_CLASSES_ROOT\.key
(Default) = "regfile"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.key
(Default) = "regfile"

HKEY_CURRENT_USER\Software\faedacacbac
CurrentPath = "%All Users Profile%\faedacacbac.exe"

Other Details

This Trojan connects to the following possibly malicious URL:

  • https://{BLOCKED}g.{BLOCKED}a/ptr/a/data.php
  • https://{BLOCKED}f.{BLOCKED}g/ptr/a/data.php
  • https://{BLOCKED}k.{BLOCKED}er.asia/ptr/a/data.php

It deletes itself after execution.