BKDR_STASER.C

May 14, 2015
 Analysis by: Homer Pacag
 ALIASES:

Trojan.Win32.Staser (Ikarus)

 PLATFORM:

Windows

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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

It executes commands from a remote malicious user, effectively compromising the affected system.

It gathers certain information on the affected computer.

It connects to certain websites to send and receive information.

  TECHNICAL DETAILS

File Size:

15,360 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 May 2015

Payload:

Compromises system security, Connects to URLs/IPs

Arrival Details

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

  • %System%\Infov.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Infov
DisplayName = Infov

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Infov
ImagePath = %System%\Infov.exe

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Infov
Start = 2

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Infov
Type = 110

Other System Modifications

This backdoor adds the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Infov

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Enum\Root\LEGACY_INFOV

Backdoor Routine

This backdoor executes the following commands from a remote malicious user:

  • Download possibly additional malicious files
  • Run/Execute application/process
  • Terminate application/process

Information Theft

This backdoor gathers the following information on the affected computer:

  • IP address and hostname
  • Logical drives (A: to Z:) types and free space
  • Root folder contents (files and folders)
  • Check and list running processes and their respective path and filename

Other Details

This backdoor connects to the following website to send and receive information:

  • www.{BLOCKED}469.com

  SOLUTION

Minimum Scan Engine:

9.750

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 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\ControlSet001\Services
    • Infov
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Enum\Root
    • LEGACY_INFOV

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.
  • %System%\Infov.exe

Step 6

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


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