BKDR_RYEJET.B

 Analysis by: Erika Bianca Mendoza

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


This backdoor may be downloaded by other malware/grayware/spyware from remote sites. It may be dropped by other malware. It may be unknowingly downloaded by a user while visiting malicious websites.

  TECHNICAL DETAILS

File Size:

69,632 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

19 Sep 2011

Arrival Details

This backdoor may be downloaded by other malware/grayware/spyware from remote sites.

It may be dropped by other malware.

It may be unknowingly downloaded by a user while visiting malicious websites.

Installation

This backdoor drops the following files:

  • %System%\logs.exe - also detected as BKDR_RYEJET.B

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)

Autostart Technique

This backdoor adds the following registry keys to install itself as a Browser Helper Object (BHO):

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{B0BEC94E-4D62-11D6-AF01-0010C6081DD0}\InprocServer32
Default = logs.exe

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{B0BEC94E-4D62-11D6-AF01-0010C6081DD0}

NOTES:

This backdoor attempts to connect to the following C&C server:

  • www.{BLOCKED}day.com

If connection is successful, it waits for any of the following commands from a remote computer:

  • *CmdShell - execute shell via command line
  • *DelMyself - delete backdoor
  • *FileDel - delete file
  • *FileGet - get file from affected computer
  • *FileGive - download file
  • *RunCommand - execute file
  • *SysReboot - reboot affected computer

*SysInfo - this command creates the following file:

  • %System%\sysinfo.txt
This file contains the following information:
  • file version
  • hostname
  • IP address
  • list drives (type, free space)
  • memory status
  • OS
  • processor
  • username

The created file is then sent to the C&C server via HTTP POST.

*FileDirList - this command lists all files in a specified directory. It creates the following file:

  • %System%\dirlist.txt

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.439.00

FIRST VSAPI PATTERN DATE:

19 Sep 2011

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

Close all opened browser windows

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\Classes\CLSID\{B0BEC94E-4D62-11D6-AF01-0010C6081DD0}\InprocServer32
    • Default = logs.exe

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.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects\{B0BEC94E-4D62-11D6-AF01-0010C6081DD0}

Step 5

Search and delete this file

[ 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. %System%\sysinfo.txt
%System%\dirlist.txt

Step 6

Scan your computer with your Trend Micro product to delete files detected as BKDR_RYEJET.B. 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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