Analysis by: Kerstan Josef Navarro
ALIASES:

Trojan:Win32/Sisron (Microsoft), Backdoor.Win32.Pushdo.qit, Win32/Kryptik.BDLB (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: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  TECHNICAL DETAILS

File Size: 39936 bytes
File Type: EXE
File Compression: UPX
Memory Resident: Yes
Initial Samples Received Date: 20 Jun 2013

Installation

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

  • %User Profile%\soxfyxwuwaxi.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 backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
soxfyxwuwaxi = "%UserProfile%\soxfyxwuwaxi.exe"

Other System Modifications

This backdoor adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
AppManagement = "{random values}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion
soxfywuwaxizap = "{random values}"

Backdoor Routine

This backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}vare.com
  • {BLOCKED}ta.org

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.984.03
VSAPI OPR PATTERN File: 9.985.00

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

Identify and terminate files detected as BKDR_PUSHDO.FH

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

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\Run
    • soxfyxwuwaxi = "%UserProfile%\soxfyxwuwaxi.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
    • AppManagement = "{random values}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion
    • soxfywuwaxizap = "{random values}"

Step 5

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


Did this description help? Tell us how we did.