WORM_BUZUS.I

 Analysis by: Pearl Charlaine Espejo

 ALIASES:

Trojan.Buzus (Malwarebytes); Trojan:Win32/Bagsu!rfn (Microsoft); W32/Buzus.SJD!tr (Fortinet); Gen:Variant.Buzus.4 (GData)

 PLATFORM:

Windows

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

  • 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.

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:

97,312 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Dec 2015

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:

  • %Application Data%\Readers_sl.exe

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Adobe Reader Speed Launchers = "%Application Data%\Readers_sl.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
patches = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Adobe Reader Speed Launchers = "\Readers_sl.exe"

Propagation

This worm creates the following folders in all removable drives:

  • {drive letter}:\RECYCLER\
  • {drive letter}:\RECYCLER\{SID}

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

  • {drive letter}:\RECYCLER\{SID}\autorunme.scr

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

Dropping Routine

This worm drops the following files:

  • {drive letter}:\RECYCLER\{SID}\Desktop.ini

  SOLUTION

Minimum Scan Engine:

9.800

FIRST VSAPI PATTERN FILE:

12.286.05

FIRST VSAPI PATTERN DATE:

21 Jan 2016

VSAPI OPR PATTERN File:

12.287.00

VSAPI OPR PATTERN Date:

22 Jan 2016

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

Restart in Safe Mode

[ 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • Adobe Reader Speed Launchers = "%Application Data%\Readers_sl.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • patches = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • Adobe Reader Speed Launchers = "\Readers_sl.exe"

Step 4

Search and delete these files

[ 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.
  • {drive letter}:\AuToRUn.iNf
  • {drive letter}:\RECYCLER\{SID}\Desktop.ini

Step 5

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