WORM_PUSHBOT.AO

 Analysis by: Roland Marco Dela Paz

 ALIASES:

Microsoft : Worm:Win32/Pushbot.gen!C; Mcafee : W32/Checkout!n

 PLATFORM:

Windows 2000, XP, Server 2003

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via removable drives


This worm arrives by connecting affected removable drives to a system. It may be unknowingly downloaded by a user while visiting malicious websites.

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

It connects to a website to send and receive information.

  TECHNICAL DETAILS

File Size:

942,080 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 Aug 2010

Arrival Details

This worm arrives by connecting affected removable drives to a system.

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

Installation

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

  • %Windows%\IMBot11.exe

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

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\Run
IMBot11 = "IMBot11.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Terminal Server\
Install\Software\Microsoft\
Windows\CurrentVersion\Run
IMBot11 = "IMBot11.exe"

Other System Modifications

This worm adds the following registry keys:

HKEY_CLASSES_ROOT\CLSID\{62366775-2A45-7E34-4FE8-CCD65283E88E}

It creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
{malware path and file name} = "{malware path and file name}:*:Enabled:IMBot11"

Propagation

This worm creates the following folders in all removable drives:

  • [DRIVE]:\Autorun
  • [DRIVE]:\Autorun\{numbers}

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

  • [DRIVE]:\Autorun\{numbers}\Autorun.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]
open=.Autorun\{numbers}\Autorun.exe
icon=%SystemRoot%\system32\SHELL32.dll,4
action=Open Folder With Explorer
shell\open=Open
shell\open\command=.Autorun\{numbers}\Autorun.exe
shell\open\default=1

Backdoor Routine

This worm connects to the following websites to send and receive information:

  • {BLOCKED}r0.yi.org

  SOLUTION

Minimum Scan Engine:

8.900

VSAPI OPR PATTERN File:

7.363.00

VSAPI OPR PATTERN Date:

04 Aug 2010

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 terminate files detected as WORM_PUSHBOT.AO

[ Learn More ]
  1. Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.

Step 3

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.

 
  • In HKEY_CLASSES_ROOT\CLSID
    • {62366775-2A45-7E34-4FE8-CCD65283E88E}

Step 4

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\Run
    • IMBot11 = "IMBot11.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Terminal Server\Install\Software\Microsoft\Windows\CurrentVersion\Run
    • IMBot11 = "IMBot11.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • {malware path and file name} = "{malware path and file name}:*:Enabled:IMBot11"

Step 5

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.
  • [DRIVE]:\Autorun

Step 6

Search and delete AUTORUN.INF files created by WORM_PUSHBOT.AO that contain these strings

[ Learn More ]
[autorun]
open=.Autorun\{numbers}\Autorun.exe
icon=%SystemRoot%\system32\SHELL32.dll,4
action=Open Folder With Explorer
shell\open=Open
shell\open\command=.Autorun\{numbers}\Autorun.exe
shell\open\default=1

Step 7

Scan your computer with your Trend Micro product to delete files detected as WORM_PUSHBOT.AO. 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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