Analysis by: Sabrina Lei Sioting
ALIASES:

TrojanDownloader:Win32/Dogkild.L (Microsoft), Trojan Horse (Symantec), Generic Dropper.fi (McAfee), W32/Dropper.PT!tr.dldr (Fortinet), Trj/Lineage.BZE (Panda)

 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: No

  • 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 disables antivirus services. This is done to allow this malware to perform its routines, avoiding removal from the system.

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size: 39,944 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 22 May 2009

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:

  • %System%\scvhost.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
RsTray = "%System%\scvhost.exe"

Process Termination

This Trojan disables antivirus services by terminating the following services if found on the affected system:

  • ekrn.exe
  • egui.exe

Dropping Routine

This Trojan drops the following files:

  • %Windows%\{random}test.dll - detected as TROJ_KILLAV.RCC
  • %Windows%\{random}text.exe - detected as TROJ_QHOST.SMB
  • %System%\drivers\pcidump.sys - detected as TROJ_RKPROC.AJ

(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 6.144.03
FIRST VSAPI PATTERN DATE: 22 May 2009

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

Remove the malware/grayware file dropped/downloaded by TROJ_GERAL.AA

    TROJ_KILLAV.RCC
    TROJ_QHOST.SMB
    TROJ_RKPROC.AJ

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • RsTray = "%System%\scvhost.exe"

Step 5

Scan your computer with your Trend Micro product to delete files detected as TROJ_GERAL.AA. 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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