Bl00dy Ransomware Gang Strikes Education Sector with Critical PaperCut Vulnerability
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2023-27350 | Authentication Bypass Leading to SYSTEM RCE in PaperCut MF/NG PaperCut MF and PaperCut NG print management software contain an improper access control flaw (CWE-284) in the SetupCompleted class that allows an unauthenticated attacker to bypass authentication and reach internal administrative functionality. The flaw is triggered by sending crafted, unauthenticated requests to the PaperCut application's web interface, without requiring valid user credentials. A successful attacker gains the ability to execute code in the context of the SYSTEM account on the PaperCut server, typically a Windows print server, giving full control of that host. Any organization running PaperCut MF or NG is potentially affected, and exposure is highest where the server's web interface is reachable from the internet or by untrusted networks. Exploitation is confirmed in the wild: CISA added the flaw to the KEV on 2023-04-21 with known ransomware use, and EPSS rates exploitation probability at 100% within 30 days. Do: Apply the vendor's updates as instructed (this is the required action in CISA KEV) — upgrade PaperCut MF/NG to the patched releases listed in PaperCut's security advisory rather than relying on unpatched installs. Until patched, restrict network access to the PaperCut web/admin interface so it is reachable only from trusted hosts, and check the server for signs of compromise given known ransomware use. Prioritize internet-facing PaperCut servers, which public scans show are exposed in the thousands. | 9.8 | 100% | KEV ransomware PoC ×3 |
| masstens of thousands of organizations (~70k+) and millions of users; thousands of internet-exposed PaperCut servers |
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Ravie LakshmananMay 12, 2023Vulnerability / Ransomware
U.S. cybersecurity and intelligence agencies have warned of attacks carried out by a threat actor known as the Bl00dy Ransomware Gang that attempt to exploit vulnerable PaperCut servers against the education facilities sector in the country.
The attacks took place in early May 2023, the Federal Bureau of Investigation (FBI) and Cybersecurity and Infrastructure Security Agency (CISA) said in a joint cybersecurity advisory issued Thursday.
"The Bl00dy Ransomware Gang gained access to victim networks across the Education Facilities Subsector where PaperCut servers vulnerable to CVE-2023-27350 were exposed to the internet," the agencies said.
"Ultimately, some of these operations led to data exfiltration and encryption of victim systems. The Bl00dy Ransomware Gang left ransom notes on victim systems demanding payment in exchange for decryption of encrypted files."
Additionally, the Bl00dy actors are said to have used TOR and other proxies from within victim networks for external communications in an attempt to mask malicious traffic and avoid detection.
CVE-2023-27350 is a now-patched critical security flaw affecting some versions of PaperCut MF and NG that enables a remote actor to bypass authentication and conduct remote code execution on the following affected installations: 8.0.0 to 19.2.7, 20.0.0 to 20.1.6, 21.0.0 to 21.2.10, and 22.0.0 to 22.0.8.
Malicious exploitation of the vulnerability has been observed since mid-April 2023, with attacks primarily weaponizing it to deploy legitimate remote management and maintenance (RMM) software and use the tool to drop additional payloads such as Cobalt Strike Beacons, DiceLoader, and TrueBot on compromised systems.
The disclosure comes as cybersecurity firm eSentire unearthed new activity targeting an unnamed education sector customer that involved the exploitation of CVE-2023-27350 to drop an XMRig cryptocurrency miner.
Attacks against PaperCut print management servers have also been deployed by Iranian state-sponsored threat groups Mango Sandstorm (aka MuddyWater or Mercury) and Mint Sandstorm (aka Phosphorus), Microsoft revealed last week.
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