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WORM_BIFROSE.WZP

September 06, 2017
 Analysis by: Byron Jon Gelera
 ALIASES:

Backdoor:Win32/Bifrose(Microsoft); W32/Autorun.CXP!tr (Fortinet); Win32/Agent.NJO(ESET)

 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:

Downloaded from the Internet, Propagates via removable drives


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 copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names.

It does not have any backdoor routine.

As of this writing, the said sites are inaccessible.

  TECHNICAL DETAILS

File Size:

123,392 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 Sep 2017

Payload:

Connects to URLs/IPs, Downloads files, Drops files

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 and executes them:

  • %All Users Profile%\CacheMgr.exe (Windows Vista and above)
  • %All Users Profile%\Application Data\CacheMgr.exe (Windows XP and below)
  • %System Root%\RECYCLER.xxx\CacheMgr.exe

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It drops the following files:

  • %All Users Profile%\csetup.tmp (Windows Vista and above)
  • %All Users Profile%\Application Data\csetup.tmp (Windows XP and below)

(Note: %All Users Profile% is the All Users folder, where it usually is C:\Documents and Settings\All Users on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\ProgramData 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.)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • 2CBE016A-8F28-4E0C-83A6-6079161294D7
  • Bif123

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\2CBE016A-8F28-4E0C-83A6-6079161294D7
StubPath = "%All Users Profile%\CacheMgr.exe" -ax

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
StubPath = "%All Users Profile%\Application Data\CacheMgr.exe" -as

Propagation

This Worm drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names.

Backdoor Routine

This Worm does not have any backdoor routine.

Download Routine

This Worm connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}es.com/ABIUS/setup.exe

It saves the files it downloads using the following names:

  • %User Temp%\cac{random}.tmp

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp 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.)

As of this writing, the said sites are inaccessible.

Other Details

This Worm connects to the following URL(s) to check for an Internet connection:

  • 74.125.224.112
  • 74.125.224.113
  • 74.125.224.114
  • 74.125.224.115
  • 74.125.224.116
  • 207.46.197.32
  • 207.46.232.182
  • 129.42.38.1
  • 198.133.219.25

It does the following:

  • The malware drops a copy of itself in the root folders of removable drives using the names of existing folders and appends the extension exe. In addition, the malware changes the attributes of the said folders to HIDDEN making sure that the copies of itself are the one visible with the file names of the folders.

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.640.03

FIRST VSAPI PATTERN DATE:

05 Sep 2017

VSAPI OPR PATTERN File:

13.641.00

VSAPI OPR PATTERN Date:

06 Sep 2017

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

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\Active Setup\Installed Components\2CBE016A-8F28-4E0C-83A6-6079161294D7
    • StubPath = "%All Users Profile%\CacheMgr.exe" -ax
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • StubPath = "%All Users Profile%\Application Data\CacheMgr.exe" -as

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.
  • %All Users Profile%\csetup.tmp (Windows Vista and above)
  • %All Users Profile%\Application Data\csetup.tmp (Windows XP and below)
  • %User Temp%\cac{random}.tmp

Step 6

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

Step 7

Scan your computer with your Trend Micro product to delete files detected as WORM_BIFROSE.WZP. 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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