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WORM_PHOREX.B

January 03, 2014
 Analysis by: Jaime Benigno Reyes
 ALIASES:

PWS:Win32/Phorex.A (Microsoft), Trojan-PSW.Win32.LdPinch.guf (Kaspersky)

 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: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via removable drives

This worm 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 Task Manager, Registry Editor, and Folder Options.

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

  TECHNICAL DETAILS

File Size:

348,160 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Dec 2013

Payload:

Collects system information, Connects to URLs/IPs

Arrival Details

This worm 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 worm drops the following component file(s):

  • %System%\syswinv32.dll - contains logged keystrokes and title of accessed applications

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

It drops the following copies of itself into the affected system:

  • %System%\lkavs3d.exe
  • %System%\netstsys.exe
  • %System%\rdatdll5.exe
  • %System%\wndscsy.exe

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

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunOnce
System Servicet = "rdatdll5.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\Run
Options3 = "rdatdll5.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Winlogo Startupc = "explorer.exe rdatdll5.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Settings2 = "rdatdll5.exe"

Other System Modifications

This worm creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoFolderOptions = "1"

Propagation

This worm drops the following copy(ies) of itself in all removable drives:

  • {removable drive letter}:\chuj.exe
  • {removable drive letter}:\dideli_papai.scr

It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.

The said .INF file contains the following strings:

[autorun]
action=Windows Picture and Fax Viewer
open=chuj.exe
icon=chuj.exe

Information Theft

This worm gathers the following data:

  • computer name
  • operating system information
  • volume information
  • processor information
  • contents of %System%\syswinv32.dll

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

Stolen Information

This worm sends the gathered information via HTTP POST to the following URL:

  • http://{BLOCKED}.{BLOCKED}.166.58/m.php

NOTES:

This worm connects to the following URLs to receive information:

  • http://{BLOCKED}riends.org/index.html - currently inaccessible
  • http://{BLOCKED}45.{BLOCKED}b.com/index.htm - currently accessible
  • http://{BLOCKED}45.{BLOCKED}s.com/index.html - currently inaccessible
  • http://www.{BLOCKED}s.lt/forumas/member.php?u=27575 - currently inaccessible
  • http://www.{BLOCKED}ums.com/members/20086-ilovemydog1.html - currently inaccessible

The worm will then decrypt the information in memory to identify the C&C server where it will send the stolen information.

  SOLUTION

Minimum Scan Engine:

9.700

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

Scan your computer with your Trend Micro product and note files detected as WORM_PHOREX.B

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

Step 5

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\RunOnce
    • System Servicet = "rdatdll5.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\Run
    • Options3 = "rdatdll5.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Winlogo Startupc = "explorer.exe rdatdll5.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Settings2 = "rdatdll5.exe"

Step 6

Search and delete this file

[ 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%\syswinv32.dll

Step 7

Search and delete AUTORUN.INF files created by WORM_PHOREX.B that contain these strings

[ Learn More ]
  • [autorun]
  • action=Windows Picture and Fax Viewer
  • open=chuj.exe
  • icon=chuj.exe

Step 8

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