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[Metallica]

Content is republished with permission from Malwarebytes.

What is OfferCore?

The Malwarebytes research team has determined that OfferCore is a bundler. These bundlers typically install potentially unwanted programs (PUPs) or adware on top of the desired software.
This one does not intall the coveted software but drops a txt file called Last_Step which contains a link to a file detected as malware.

How do I know if my computer is affected by OfferCore?

You may see these warnings during install:







and extra offers preented like this:



How did OfferCore get on my computer?

Bundlers use different methods for distributing themselves. This particular one was offered up on software download sites, where people look for games they like.

How do I remove OfferCore?

Our program Malwarebytes can detect and remove this bundler.

• Please download Malwarebytes for Windows to your desktop.
• Double-click MBSetup.exe and follow the prompts to install the program.
• When your Malwarebytes for Windows installation completes, the program opens to the Welcome to Malwarebytes screen.
• Click on the Get started button.
• Click Scan to start a Threat Scan.
• When the scan is finished click Quarantine to remove the found threats.
• Reboot the system if prompted to complete the removal process.

Is there anything else I need to do to get rid of OfferCore?

• No, Malwarebytes removes OfferCore completely.
• If you wish to remove the installed programs you can use the normal procedure from the Windows Control Panel.

How would the full version of Malwarebytes help protect me?

We hope our application and this guide have helped you eradicate this bundler.

As you can see below the full version of Malwarebytes would have protected you against the OfferCore bundler. It would have blocked the installer before it became too late.

Malwarebytes blocks the installer

Malwarebytes blocks the downloadlink

Technical details for experts

Possible signs in FRST logs:

C:\Users\{username}\Downloads\Last_Step.txt

Significant changes made by the installer:

File system details [View: All details] (Selection)
---------------------------------------------------
    In the existing folder C:\Users\{username}\Downloads
       Adds the file Furk Ultra - Linkvertise Downloader_arBWu-1.exe"="4/30/2021 9:06 AM, 2686928 bytes, A
    In the existing folder C:\Users\{username}\Downloads
       Adds the file Last_Step.txt"="4/30/2021 9:08 AM, 151 bytes, A

Malwarebytes log:

Malwarebytes
www.malwarebytes.com

-Log Details-
Scan Date: 4/30/21
Scan Time: 9:18 AM
Log File: 45ee1032-a984-11eb-bc5e-080027235d76.json

-Software Information-
Version: 4.3.0.98
Components Version: 1.0.1273
Update Package Version: 1.0.39957
License: Premium

-System Information-
OS: Windows 7 Service Pack 1
CPU: x64
File System: NTFS
User: {username}-PC\{username}

-Scan Summary-
Scan Type: Threat Scan
Scan Initiated By: Manual
Result: Completed
Objects Scanned: 234039
Threats Detected: 3
Threats Quarantined: 3
Time Elapsed: 3 min, 17 sec

-Scan Options-
Memory: Enabled
Startup: Enabled
Filesystem: Enabled
Archives: Enabled
Rootkits: Disabled
Heuristics: Enabled
PUP: Detect
PUM: Detect

-Scan Details-
Process: 0
(No malicious items detected)

Module: 0
(No malicious items detected)

Registry Key: 0
(No malicious items detected)

Registry Value: 0
(No malicious items detected)

Registry Data: 0
(No malicious items detected)

Data Stream: 0
(No malicious items detected)

Folder: 0
(No malicious items detected)

File: 1
PUP.Optional.OfferCore, C:\USERS\{username}\DOWNLOADS\FURK ULTRA - LINKVERTISE DOWNLOADER_ARBWU-1.EXE, Quarantined, 556, 930420, 1.0.39957, , ame, , 6553DAC1C066522C1517EED6FF43A47D, 915E3096A38D9863A4A555B2F22F50CB892293C36DBF71B031917F4AC7F96645

Physical Sector: 0
(No malicious items detected)

WMI: 0
(No malicious items detected)


(end)

As mentioned before the full version of Malwarebytes could have protected your computer against this threat.
We use different ways of protecting your computer(s):

• Dynamically Blocks Malware Sites & Servers
• Malware Execution Prevention

Save yourself the hassle and get protected.