Analysis by: Jimelle Monteser

ALIASES:

Trojan-Downloader.Win32.Pher.arp (Kaspersky), VirTool:Win32/Injector.gen!AD (Microsoft), Trojan-Downloader.Win32.Pher (Ikarus)

 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:

  • In the wild: Yes

  OVERVIEW

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.

  TECHNICAL DETAILS

File Size: 133,632 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 08 Oct 2013

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 copies of itself into the affected system:

  • %System Root%\RECYCLER\{CLSID}\rndl.exe

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It creates the following folders:

  • %System Root%\RECYCLER
  • %System Root%\RECYCLER\{CLSID}
  • {Removable Drive Letter}:\tasumae

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Taskman = "%System Root%\RECYCLER\{CLSID}\rndl.exe"

Propagation

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

  • {Removable Drive Letter}:\tasumae\2349284.exe

Dropping Routine

This worm drops the following files:

  • %System Root%\RECYCLER\{CLSID}\Desktop.ini
  • {Removable Drive Letter}:\tasumae\Desktop.ini
  • {Removable Drive Letter}:\autorun.inf

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Other Details

This worm connects to the following possibly malicious URL:

  • {BLOCKED}no.com
  • {BLOCKED}pi.net
  • {BLOCKED}do.org

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.328.06
FIRST VSAPI PATTERN DATE: 08 Oct 2013
VSAPI OPR PATTERN File: 10.329.00
VSAPI OPR PATTERN Date: 09 Oct 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

Identify and delete files detected as WORM_PALEVO.ARK using the Recovery Console

[ 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 NT\CurrentVersion\Winlogon
    • Taskman = "%System Root%\RECYCLER\{CLSID}\rndl.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.
  • System Root%\RECYCLER
  • {Removable Drive Letter}:\tasumae

Step 5

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.
  • {Removable Drive Letter}:\autorun.inf

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_PALEVO.ARK. 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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