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Threat Encyclopedia

PE_XPAJ.C

ANALYSIS BY

Erika Bianca Mendoza


ALIASES:

Virus:Win32/Xpaj.B (Microsoft), W32/Xpaj.c (McAfee), W32.Xpaj.B (Symantec)

PLATFORM:

Windows 2000, Windows, XP, Windows Server 2003, Windows Vista, Windows 7

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

  • Threat Type:File infector

  • Destructiveness:No

  • Encrypted: Yes

  • In the wild: Yes

OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware, Infects files


This file infector is part of a malware family that has affected users in Australia and several other countries on October 2012. Besides infecting files, it also infects the affected system's (MBR) Master Boot Record in order to automatically load itself at system startup, making removal difficult.

To get a one-glance comprehensive view of the behavior of this File infector, refer to the Threat Diagram shown below.

This file infector arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It infects certain file types by inserting code in the said files. It infects the Master Boot Record of the affected system.

TECHNICAL DETAILS

File Size:

Varies

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

30 Nov 2011

Payload:

Connects to URLs/IPs, Compromises system security, Terminates processes

Arrival Details

This file infector arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

File Infection

This file infector infects files with the following file extensions by inserting code in the said files:

  • DLL
  • EXE
  • SCR
  • SYS

It infects the Master Boot Record of the affected system in order to perform the following routines:

  • terminate several AV processes
  • inject code to browser to download encrypted files
  • automatically load PE_XPAJ.C-O every time the system boots.

Process Termination

This file infector terminates the following processes if found running in the affected system's memory:

  • avp.exe
  • avgnt.exe
  • avguard.exe
  • sched.exe
  • avastui.exe
  • ccsvchst.exe
  • avgcsrvx.exe
  • avgnsx.exe
  • avgrsx.exe
  • avgtray.exe
  • avgwdsvc.exe
  • egui.exe

Other Details

This file infector connects to the following URL(s) to check for an Internet connection:

  • microsoft.com

It connects to the following possibly malicious URL:

  • {BLOCKED}.{BLOCKED}.162.208:35516
  • {BLOCKED].{BLOCKED}.152.218:35516
  • {BLOCKED}.{BLOCKED}.71.249:35516
  • {BLOCKED}.{BLOCKED}.60.108:35516
  • {BLOCKED}.{BLOCKED}.123.153:35516
  • {BLOCKED}.{BLOCKED}.132.25:35516
  • {BLOCKED}.{BLOCKED}.183.224:35516
  • {BLOCKED}.{BLOCKED}.204.90:80
  • {BLOCKED}biok.info
  • {BLOCKED}c.com
  • {BLOCKED}kv.com
  • {BLOCKED}tss.info
  • {BLOCKED}ifhrf.net
  • {BLOCKED}kowab.ru
  • {BLOCKED}elertiong.com
  • {BLOCKED}xw.ru
  • {BLOCKED}naf.ru
  • {BLOCKED}ppsfm.org
  • {BLOCKED}r.info
  • {BLOCKED}j.info
  • {BLOCKED}bkxfn.biz
  • {BLOCKED}hpte.com
  • {BLOCKED}e.ru
  • {BLOCKED}fbxrzn.com
  • {BLOCKED}etobob.biz
  • {BLOCKED}mullpy.info
  • {BLOCKED}th.info
  • {BLOCKED}medescriptor.com
  • {BLOCKED}sncki.info
  • {BLOCKED}hyjku.net
  • {BLOCKED}mpyzh.net
  • {BLOCKED}hez.com
  • {BLOCKED}knddy.com
  • {BLOCKED}vaweonearch.com
  • {BLOCKED}qyhqtb.org
  • {BLOCKED}gnfvhz.ru
  • {BLOCKED}l.ru
  • {BLOCKED}cut.biz
  • {BLOCKED}pq.info
  • {BLOCKED}eucnd.biz
  • {BLOCKED}o.net
  • {BLOCKED}ront.net
  • {BLOCKED}rando.com
  • {BLOCKED}minestar.org
  • {BLOCKED}sysho.com
  • {BLOCKED}niolosto.com
  • {BLOCKED}usiceditior.com

NOTES:

This file infector downloads several encrypted files. It saves the downloaded files as %Windows%\{random file name}.{random 3 letters}. Upon analysis, a minimum of nine encrypted files are downloaded. These files may also perform file infection and MBR infection.

It generates 197 URLs to connect to using a Domain Generation Algorithm.

It also runs in 64-bit versions of Windows.

It maintains only one main execution of the malware code per unique infected sample per day.

The modified MBR is detected as BOOT_XPAJ.SM.

SOLUTION

Minimum Scan Engine:

9.300

FIRST VSAPI PATTERN FILE:

8.615.00

FIRST VSAPI PATTERN DATE:

30 Nov 2011

VSAPI OPR PATTERN File:

9.475.00

VSAPI OPR PATTERN Date:

21 Oct 2012

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 PE_XPAJ.C

[ 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

Scan your computer with your Trend Micro product to clean files detected as PE_XPAJ.C. 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.

Step 4

Search and delete this file

[ Learn More ]
There may be some 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.
  • %Windows%\{random file name}.{random 3 letters}

Step 5

Restore your system's Master Boot Record (MBR)

To restore your system's Master Boot Record (MBR):

• On Windows 2000, XP, and Server 2003:

  1. Insert your Windows Installation CD into your CD drive then restart your computer.
  2. When prompted, press any key to boot from the CD.
  3. On the Main Menu, type r to enter the Recovery Console.
    (Note for Windows 2000: After pressing r, type c to choose the Recovery Console on the repair options screen.)
  4. Type the number that corresponds to the drive and folder that contains Windows (usually C:\WINDOWS) and press Enter.
  5. Type your Administrator password and press Enter.
  6. In the input box, type the following then press Enter:
    fixmbr {affected drive}
  7. Type exit and press Enter to restart the system normally.

• On Windows Vista and 7:

  1. Insert your Windows Installation DVD into the DVD drive, then press the restart button on your computer.
  2. When prompted, press any key to boot from the DVD.
  3. Depending on your Windows Installation DVD, you might be required to choose the installation language. On the Install Windows window, choose your language, locale, and keyboard layout or input method. Click Repair your computer.
  4. Select Use recovery tools that can help fix problems starting Windows. Select your installation of Windows. Click Next.
  5. If the Startup Repair window appears, click Cancel, Yes, then Finish.
  6. In the System Recovery Options menu, click Command Prompt.
  7. In the Command Prompt window, type the following then press Enter:
    BoorRec.exe /fixmbr
  8. Type exit and press Enter to close the Command Prompt window.
  9. Click Restart to restart your computer normally.

NOTES:

Trend Micro Rescue Disk scans and cleans systems infected with XPAJ variants. For further instructions on how to use this tool, you may refer to the Rescue Disk Instruction Page.


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