OnlyFans – an attractive brand for hopeful users and their attackers.
CRPx0 is a complex, stealthy and persistent malware campaign. It currently targets macOS and Windows systems, and appears to have Linux capabilities in development. It currently comprises cryptocurrency theft followed by large scale data exfiltration and ransomware.
The campaign has been analyzed (PDF) in detail by Aryaka Threat Research Labs.
The initial social engineering lure is the offer of a free OnlyFans account. Users interested in free access to OnlyFans might actively search for available options, and stumble across the threat actors’ OnlyfansAccounts.zip. By looking for unauthorized free access to paid-for content, these users have already demonstrated a willingness to be risk takers open to less than legitimate activity. They would be more willing to download the zip, and to accept that acquiring a free account might require some non-standard activity. That’s a good start for any attacker.
The malicious zip contains a shortcut file (Onlyfans Accounts.lnk) which would appear to be a legitimate next step in pursuing a non-legitimate purpose. There is no apparent reason for the risk taker not to proceed.
The lnk provides a file that appears to contain the promised account credentials. It is titled Accounts.txt, has the headline ’50 working Onlyfans account’ and lists what appears to be credentials – but in the background, it begins to install the malware. The attackers maintain control from their C2 while the malware collects environment data and establishes persistence. The malware even calls home periodically to see if there is a newer version of itself, and updates itself as necessary.
There are three primary effects of CRPx0 campaign: cryptocurrency theft, data exfiltration, and delivery of ransomware.
The crypto theft is achieved by continuously monitoring the system clipboard. If the victim copies a wallet address (while sending or receiving funds), this is detected – and the address switched out for one controlled by the attackers. So, if users copy their wallet address to give to the sender (ready to receive the crypto), they actually instruct the sender to send the money to the threat actors who receive the crypto.
The second phase of the campaign is data exfiltration – the first part of a double extortion process. The data to be stolen is selected by the attackers via the C2. It will correlate with the user data that is subsequently encrypted – such as documents, media and images, emails, developer and code files, and engineering and design files.
Once this data has been stolen, the attackers move to the encryption phase. “When the malware receives the ‘encryption’ command,” explains the analysis, “it downloads the crypter.py payload from a remote server and saves it locally. Once the file is successfully written, it is executed using the system’s Python interpreter.”
A unique key is generated using the Fernet mechanism for AES encryption and sent to the C2. The targeted files are read, encrypted and saved with the extension ‘.crpx0’. Specific system and critical directories are excluded to ensure the system remains stable despite the ransomware. The desktop wallpaper is exchanged for the attackers’ ‘gotcha’ image, and ransom instruction notes are dropped in English, Russian, and Chinese. Victims are instructed to contact the attackers through multiple channels (including email, qTox, and Telegram).
The campaign maintains its own leaks site. At the time of writing, it claims 38 victims compromised so far, with 23 leaks available. It also claims to have stolen a massive 10,839 terabytes of data. The remaining 15 victims have either paid the ransom, or the deadline for payment has not yet expired.
Where the stolen data is available, it is being offered for a one-time fee of $500 in cryptocurrency. This provides ‘Lifetime access to all current and future leaks’, with ‘No monthly recurring charges’.
“This attack is a highly organized, multi-platform threat that targets Windows and macOS, with potential support for Linux,” summarizes Aryaka. “Its capabilities include cryptocurrency theft, wallet seed phrase harvesting, deploying additional malicious payloads, and full-scale ransomware encryption. The operation is modular and adaptable, allowing attackers to escalate from opportunistic theft to large-scale data exfiltration and double extortion.”
There is no apparent targeting in this campaign. It could be any user looking for a free OnlyFans account (hence, perhaps, the ransom notes appearing in English, Russian and Chinese). However, victims are more likely to be using their own personal device in the first instance. Most employees would be aware that the security department can readily see where they are going on a company device while in the office.
Aryaka’s write-up includes a list of IoCs, and a mapping to MITRE ATT&CK.
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