[BreachExchange] MegaCortex ransomware variant threatens data breach, alters credentials

[Destry Winant]

https://www.scmagazine.com/home/security-news/ransomware/megacortex-ransomware-variant-threatens-data-breach-alters-credentials/

A newly discovered variant of MegaCortex ransomware goes well beyond
just encrypting victims’ files — it also changes their Windows
passwords and threatens to publish their stolen data if they fail to
pay.

In a report earlier this week, BleepingComputer said it helped
analyzed the new strain after it was discovered by MalwareHunterTeam
and subsequently reverse engineered by researcher Vitali Kremez.

“All of your user credentials have been changed and your files have
been encrypted,” the ransomware note warns infected victims. Both
threats are true: files are encrypted and given an .m3g4c0rtx
extension, and victims who attempt to log in to their system will find
that they cannot. Instead, all they will see is a legal notice that
says “Locked by MegaCortex,” along with the attacker-controlled email
addresses to contact.

The credential change is made possible by executing the net user
command when the ransomware is executed, BleepingComputer reported,
citing Kremez.

The ransom note also makes a second threat: “We have also downloaded
your data to a secure location. In the unfortunate event of us not
coming to an agreement, we will have no choice but to make this data
public.” It is has been confirmed if the MegaCortex attacks actually
have this capability.

The file encryption is reportedly conducted by two extracted DLL
files, while a trio of CMD files are leveraged to remove shadow volume
copies, wipe free space on the C:\ drive, create the aforementioned
legal notice and clean up the malicious files.