WORM_FAKEFLDR.AI

 Analysis by: Henry Alarcon Jr.

 ALIASES:

Worm.Win32.FakeFolder.a (Kaspersky), Trojan.Generic.6048691 (Bitdefender), Worm/Pakes.BXQ (AVG)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW


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.

  TECHNICAL DETAILS

File Size:

48,640 bytes

File Type:

EXE

Memory Resident:

No

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.

Autostart Technique

This Worm creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKLM\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
(Default) = %Program Files%\system.caca

Other System Modifications

This Worm adds the following registry keys:

HKLM\SOFTWARE\Classes\
cacafile

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.caca

It adds the following registry entries:

HKLM\SOFTWARE\Classes\
.caca
(Default) = cacafile

HKLM\SOFTWARE\Classes\
cacafile\shell\open\
command
(Default) = C:\Program Files\Internet Explorer\WINLOGON.exe

Propagation

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

  • {removable drive letter}:\MyDocument.exe

Dropping Routine

This Worm drops the following files:

  • %Program Files%\Internet Explorer\WINLOGON.exe
  • %Program Files%\system.caca

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), 7 (32-bit), and 8 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), 7 (64-bit), and 8 (64-bit).)

Other Details

This Worm does the following:

  • It moves the files from the root directory of removable drives to the created folder {removable drive}\MyDocuments

  SOLUTION

Minimum Scan Engine:

9.850

FIRST VSAPI PATTERN FILE:

13.674.05

FIRST VSAPI PATTERN DATE:

22 Sep 2017

VSAPI OPR PATTERN File:

13.675.00

VSAPI OPR PATTERN Date:

23 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

Identify and terminate files detected as WORM_FAKEFLDR.AI

[ 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 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
    • (Default) = "%Program Files%\system.caca"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\cacafile\shell\open\command
    • (Default) = "C:\Program Files\Internet Explorer\WINLOGON.exe"

Step 5

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.
  • %Program Files%\Internet Explorer\WINLOGON.exe
  • %Program Files%\system.caca
  • {removable drive letter}:\MyDocument.exe

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_FAKEFLDR.AI. 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 the following Trend Micro Support pages for more information:


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