ALIASES:

Backdoor:Win32/FlyAgent.H (Microsoft); BackDoor-DRV.gen.c (McAfee); Backdoor.Trojan (Symantec); ARC:Embedded, PAK:[krnln.fnr]:UPX (Kaspersky); Backdoor.Win32.FlyAgent.h (v) (Sunbelt); Gen:Variant.EvilEPL.9 (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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.

  TECHNICAL DETAILS

File Size: 775,242 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 28 May 2012

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:

  • %Program Files%\Xerzsziiv.exe

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files.)

It creates the following folders:

  • %User Temp%\E_4
  • %User Temp%\BClib
  • %Program Files%\Kouzcrree

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %Program Files% is the default Program Files folder, usually C:\Program Files.)

Autostart Technique

This Trojan registers as a system service to ensure its automatic execution at every system startup by adding the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Kouzcrree\Parameters

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\rising\
KaKa

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Recovery

HKEY_CURRENT_USER\Software\FlySky\
E\Install

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\rising\
KaKa
procrun = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Check_Associations = "NO"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Recovery
AutoRecover = "2"

HKEY_CURRENT_USER\Software\FlySky\
E\Install
Path = "%User Temp%\BClib"

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Kouzcrree\Parameters
Application = "%Program Files%\Xerzsziiv.exe -s"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\E_4\krnln.fnr
  • %User Temp%\E_4\Exmlrpc.fne
  • %User Temp%\E_4\dp1.fne
  • {malware path and file name}_and xme.bat
  • %Program Files%\Xerzsziiv.dll
  • %User Temp%\_eviip.tmp
  • %Program Files%\Kouzcrree\srvany.exe
  • %Program Files%\Xerzsziiv.db
  • %Windows%\Fonts\d0ab46a4ebf1a9ec364bb3c27bac85c4.dat
  • %User Temp%\BClib\krnln.fnr
  • %User Temp%\BClib\dp1.fne
  • %User Temp%\BClib\Exmlrpc.fne
  • %User Temp%\BClib\krnln.fne

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003.. %Program Files% is the default Program Files folder, usually C:\Program Files.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ 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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Kouzcrree
    • Parameters
  • In HKEY_LOCAL_MACHINE\SOFTWARE\rising
    • KaKa
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
    • Recovery
  • In HKEY_CURRENT_USER\Software\FlySky\E
    • Install

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_LOCAL_MACHINE\SOFTWARE\rising\KaKa
    • procrun = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Check_Associations = "NO"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Recovery
    • AutoRecover = "2"
  • In HKEY_CURRENT_USER\Software\FlySky\E\Install
    • Path = "%User Temp%\BClib"
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Kouzcrree\Parameters
    • Application = "%Program Files%\Xerzsziiv.exe -s"

Step 5

Search and delete these files

[ Learn More ]
There may be some component 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.
  • %User Temp%\E_4\krnln.fnr
  • %User Temp%\E_4\Exmlrpc.fne
  • %User Temp%\E_4\dp1.fne
  • {malware path and file name}_and xme.bat
  • %Program Files%\Xerzsziiv.dll
  • %User Temp%\_eviip.tmp
  • %Program Files%\Kouzcrree\srvany.exe
  • %Program Files%\Xerzsziiv.db
  • %Windows%\Fonts\d0ab46a4ebf1a9ec364bb3c27bac85c4.dat
  • %User Temp%\BClib\krnln.fnr
  • %User Temp%\BClib\dp1.fne
  • %User Temp%\BClib\Exmlrpc.fne
  • %User Temp%\BClib\krnln.fne

Step 6

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %User Temp%\E_4
  • %User Temp%\BClib
  • %Program Files%\Kouzcrree

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_FLYSTUDIO_000001d.TOMA. 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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