WORM_PALEVO.ACR

 Analysis by: Sabrina Lei Sioting
 Modified by: Christopher Daniel So

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW


This worm arrives via removable drives.

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:

266,240 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 May 2011

Arrival Details

This worm arrives via removable drives.

Installation

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

  • %Application Data%\{random filename}.exe

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)

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 = "%Application Data%\{random file name}.exe"

Propagation

This worm creates the following folders in all removable drives:

  • AMORE

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

  • AMORE\mijo.exe

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]
shellexecute=AMORE//mijo.exe
shell\explore\command=AMORE//mijo.exe
open=AMORE///mijo.exe
icon=AMORE//mijo.exe
shell\open\command=AMORE//mijo.exe
Shell\open\command=AMORE//mijo.exe
{garbage}
USEAUTOPLAY=1
action=Open folder to view file using Windows Explorer

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

8.160.05

FIRST VSAPI PATTERN DATE:

16 May 2011

VSAPI OPR PATTERN File:

8.161.00

VSAPI OPR PATTERN Date:

16 May 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

Identify and delete files detected as WORM_PALEVO.ACR using either the Startup Disk or 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 = "%Application Data%\{random file name}.exe"

Step 4

Search and delete this folder

[ 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.
  • {removable drive letter}:\AMORE

Step 5

Search and delete AUTORUN.INF files created by WORM_PALEVO.ACR that contain these strings

[ Learn More ]


[autorun]
shellexecute=AMORE//mijo.exe
shell\explore\command=AMORE//mijo.exe
open=AMORE///mijo.exe
icon=AMORE//mijo.exe
shell\open\command=AMORE//mijo.exe
Shell\open\command=AMORE//mijo.exe
{garbage}
USEAUTOPLAY=1
action=Open folder to view file using Windows Explorer

Step 6

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