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TSPY_KEYLOGR.CSYO

September 18, 2017
 ALIASES:

Trojan:Win32/Dynamer!ac (Microsoft), Mal/FareitVB-M (SOPHOS_LITE), a variant of Win32/Injector.DODB trojan (NOD32)

 PLATFORM:

Windows

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

  • Threat Type: Trojan Spy

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan Spy 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:

524,288 bytes

Memory Resident:

Yes

Initial Samples Received Date:

01 May 2017

Arrival Details

This Trojan Spy 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 Spy drops the following copies of itself into the affected system:

  • %Application Data%\{GUID}\PCI Service\pcisv.exe
  • %Program Files%\NAT Service\natsvc.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %Program Files% is the Program Files folder, where it usually is C:\Program Files on all Windows operating system versions; C:\Program Files (x86) for 32-bit applications running on Windows 64-bit operating systems.)

It drops the following files:

  • %Application Data%\subfolder\avast.exe
  • %User Startup%\avast.vbs
  • %Application Data%\{GUID}\run.dat
  • %Application Data%\{GUID}\task.dat

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.. %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user}\Start Menu\Programs\Startup on Windows 2000 and XP, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup on Windows Vista, 7, and 8.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
PCI Service = "%Application Data%\{GUID}\PCI Service\pcisv.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
NAT Service = "%Program Files%\NAT Service\natsvc.exe"

Other System Modifications

This Trojan Spy adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Schedule\
TaskCache\Tasks\{GUID}
Path = "\NAT Service"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Schedule\
TaskCache\Tasks\{GUID}
Hash = {hex value}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Schedule\
TaskCache\Tree\NAT Service
Id = {GUID}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Schedule\
TaskCache\Tree\NAT Service
Index = "3"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Schedule\
TaskCache\Tasks\{GUID}
Triggers = {hex value}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Schedule\
TaskCache\Tree\NAT Service Task
Id = {GUID}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Schedule\
TaskCache\Tree\NAT Service Task
Index = "3"

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.374.05

FIRST VSAPI PATTERN DATE:

01 May 2017

VSAPI OPR PATTERN File:

13.375.00

VSAPI OPR PATTERN Date:

02 May 2017

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

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
    • PCI Service = "%Application Data%\{GUID}\PCI Service\pcisv.exe
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • NAT Service = "%Program Files%\NAT Service\natsvc.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tasks\{GUID}
    • Path = "\NAT Service" In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tasks\{GUID} Hash = {hex values
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\NAT
    • Service Id = {GUID}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\NAT
    • Service Index = "3"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tasks\{GUID}
    • Triggers = {hex values}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\NAT
    • Service Task Id = {GUID}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\NAT
    • Service Task Index = "3"

Step 5

Search and delete these files

[ 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.
  • %Application Data%\subfolder\avast.exe
  • %Application Data%\Microsoft\Windows\Start Menu\Programs\Startup\avast.vbs
  • %User Startup%\avast.vbs %Application Data%\{GUID}\run.dat
  • %Application Data%\{GUID}\task.dat
  • %System%\Tasks\NAT Service
  • %System%\Tasks\NAT Service Task
  • %System%\Tasks\PCI Service
  • %System%\Tasks\PCI Service Task

Step 6

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