BlackCat Ransomware Gang Targeting Unpatched Microsoft Exchange Servers

Microsoft is warning that the BlackCat ransomware crew is leveraging exploits for unpatched Exchange server vulnerabilities to gain access to targeted networks.

Upon gaining an entry point, the attackers swiftly moved to gather information about the compromised machines, followed by carrying out credential theft and lateral movement activities, before harvesting intellectual property and dropping the ransomware payload.

The entire sequence of events played out over the course of two full weeks.
"In another incident  a ransomware affiliate gained initial access to the environment via an internet-facing Remote Desktop server using compromised credentials to sign in.
BlackCat, also known by the names ALPHV and Noberus, is a relatively new entrant to the hyperactive ransomware space. It's also known to be one of the first cross-platform ransomware written in Rust, exemplifying a trend where threat actors are switching to uncommon programming languages in an attempt to evade detection.

The ransomware-as-a-service (RaaS) scheme, irrespective of the varying initial access vectors employed, culminates in the exfiltration and encryption of target data that's then held ransom as part of what's called double extortion.
The RaaS model has proven to be a lucrative gig economy-style cybercriminal ecosystem consisting of three different key players: access brokers (IABs), who compromise networks and maintain persistence; operators, who develop and maintain the ransomware operations; and affiliates, who purchase the access from IABs to deploy the actual payload.