Analysis by: Merianne Polintan
 Modified by: Rika Joi Gregorio
ALIASES:

Trojan:Win32/Seleya.A(Microsoft),Trojan.Gen(Norton),Trojan.Win32.Rorpian.d (v)(Sunbelt),W32/Rorpian.C!tr(Fortinet),Win32/Seleya.A trojan(Nod32)

 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:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: Yes

  • 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.

  TECHNICAL DETAILS

File Size: 133,632 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 22 Apr 2013
Payload: Compromises system security, Connects to URLs/IPs, Steals information

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 and executes them:

  • %User Temp%\WinUpdaterstd\svchost.exe

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It creates the following folders:

  • %User Temp%\WinUpdaterstd

(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, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
Update service = "%User Temp%\WinUpdaterstd\svchost.exe"

Backdoor Routine

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

  • simplehttpflood - HTTP flooding in simple mode
  • httpflood - HTTP flooding
  • oldhttpflood - HTTP/HTTPS flooding in the old mode
  • intoldhttpflood - HTTP/HTTPS flooding in the old intellectual mode
  • inthttpflood - HTTP flooding in intelligent mode (used to monitor user activity)
  • highhttpflood - HTTP flooding in aggressive mode
  • posthttpflood - HTTP flooding (POST)
  • intposthttpflood - HTTP flooding in intelligent mode
  • icmpflood - ICMP flooding
  • inticmpflood - ICMP flooding in intelligent mode
  • newtimeout - Change pause between requests
  • stop - cancel previous command
  • update - update itself

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • http://{BLOCKED}oid.net//./././getcmd.php?id=-{Malware ID}&traff=0

Information Theft

This backdoor attempts to steal stored account information used in the following installed File Transfer Protocol (FTP) clients or file manager software:

  • FlashFXP
  • FileZilla
  • SmartFTP
  • GHISLER
  • ALFTP

It gathers the following account information from any of the mentioned File Transfer Protocol (FTP) clients or file manager software:

  • User ID
  • Host Name
  • Password
  • Port Number

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.872.05
FIRST VSAPI PATTERN DATE: 22 Apr 2013
VSAPI OPR PATTERN File: 9.873.00
VSAPI OPR PATTERN Date: 22 Apr 2013

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

Restart in Safe Mode

[ Learn More ]

Step 3

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\policies\Explorer\Run
    • Update service = "%User Temp%\WinUpdaterstd\svchost.exe"

Step 4

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%\WinUpdaterstd

Step 5

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