WORM_TSIPI.AA

October 17, 2016
 Analysis by: Francis Xavier Antazo
 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Propagates via flashdrives, Downloaded from the Internet, Dropped by other malware

This worm arrives via removable drives. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

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

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

  TECHNICAL DETAILS

File Size:

172032 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

27 Feb 2015

Payload:

Drops files

Arrival Details

This worm arrives via removable drives.

It 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 and executes the following files:

  • %System%\send.vbs (to be detected as VBS_AUTORUN.AONP)

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

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

  • %System%\tcpip.exe

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It adds the following processes:

  • wscript.exe

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
Shell = "Explorer.exe tcpip.exe"

Other System Modifications

This worm adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings
JITDebug = "0"

Propagation

This worm drops copies of itself into all the removable drives connected to an affected system.

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

  • driver.exe
  • {subfolder}\{subfolder name}.exe
  • {subfolder}\MyPicture.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=driver.exe

Dropping Routine

This worm executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

Other Details

This worm does the following:

  • It renames the file %system%\taskmgr.exe to %system root%\taskmrg.exe effectively disabling task manager

  SOLUTION

Minimum Scan Engine:

9.800

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Restore this modified registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator’s help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "Explorer.exe tcpip.exe"
      To: Shell = "Explorer.exe"

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_CURRENT_USER\Software\Microsoft\Windows Script\Settings
    • JITDebug = "0"

Step 6

Remove malware/grayware files dropped/downloaded by WORM_TSIPI.AA. (Note: Please skip this step if the threats listed below have already been removed.)

    • VBS_AUTORUN.AONP

Step 7

Search and delete AUTORUN.INF files created by WORM_TSIPI.AA that contain these strings

[ Learn More ]
  • [autorun]
  • open=driver.exe

Step 8

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


Did this description help? Tell us how we did.