Synology warns of C3RB3R ransomware attacks targeting NAS devices

Taiwanese network-attached storage maker Synology issued an urgent advisory warning customers of ongoing C3RB3R ransomware attacks targeting DiskStation Manager appliances. Threat actors are exploiting vulnerabilities patched in December 2024 to compromise outdated systems, encrypt files, and demand ransoms. According to BleepingComputer's report, initial victim reports surfaced over two weeks before the notice after devices suffered file locking. Synology urges users to enable automatic updates and install the latest firmware immediately.

This operational security breakdown examines the ongoing ransomware campaign, affected firmware releases, and immediate mitigation steps for storage owners. The briefing is designed for system administrators, IT staff, and home laboratory users who maintain Internet-connected storage hardware. Organizations relying on central network repositories must verify their exposure to untrusted networks. Readers will find verified patch thresholds across five operating system branches, technical details on the underlying exploits, and practical configuration changes to prevent intrusion.

What broke in Synology warns of C3RB3R ransomware attacks

The primary breakdown stems from unpatched DiskStation Manager software running on storage appliances accessible over the public Internet without December 2024 security updates. Attackers identified hardware installations that missed critical patches, allowing automated exploitation scripts to gain unauthorized operating system access. While Synology did not name the specific flaw exploited, its advisory references a November 2024 alert covering critical vulnerabilities. Those patches resolved remote code execution under CVE-2024-10441, arbitrary file read under CVE-2024-50629, and arbitrary file write under CVE-2024-10445 across unpatched devices.

After breaching a vulnerable device, the malware executes encryption routines across local drives, appending the .L0CK3D extension to all encrypted files. The attack drops an extortion notice titled read-me3.txt in affected folders, instructing victims to access a dark web site and purchase a decryption tool named C3rb3r Decryptor for thousands of dollars. The advisory represents a rare alert from Synology, which last issued a warning of this severity in August 2019 after brute-force attacks spread eCh0raix ransomware across customer appliances.

Who is exposed by Synology warns of C3RB3R ransomware attacks

The threat exposes any organization or consumer running Synology network-attached storage with management interfaces exposed to public network traffic. Threat intelligence from monitoring organization Shadowserver indicates that over 380,000 Synology network-attached storage appliances are currently visible on the public Internet. Although Shadowserver does not state how many of those devices are already patched against attacks or serve as defensive honeypots, the number confirms an expansive attack surface. Automated attacker scans actively query public network ranges for exposed management interfaces to identify unpatched systems.

Exposure covers multiple DiskStation Manager operating system releases spanning five distinct software branches. Devices running versions 7.2.2, 7.2.1, 7.2, and 7.1 face critical severity risks if administrators have not installed the designated security updates. In addition, legacy appliances limited to the older 6.2 platform branch carry a moderate severity rating that demands remediation. Deployments storing corporate file shares, central databases, or system backups face immediate encryption if management portals remain accessible online without the December 2024 patches in active place.

What to do now about Synology warns of C3RB3R ransomware attacks

Administrators must immediately apply the appropriate DiskStation Manager update for their specific platform branch. Installations running DSM 7.2.2 must upgrade to version 7.2.2-72806-1 or above, while DSM 7.2.1 systems must update to 7.2.1-69057-6 or higher. Appliances using DSM 7.2 require build 7.2-64570-4 or above, and DSM 7.1 deployments must install build 7.1.1-42962-7 or above. Systems on DSM 6.2 need build 6.2.4-25556-8 or higher. Synology also strongly recommends enabling automatic updates inside system settings to ensure future patches install without manual delay.

In addition to installing software updates, administrators must immediately block external Internet access to the management web interface. Severing public access prevents automated threat scanners from interacting with the administration login portal. Network operators should disable universal plug-and-play port forwarding on routers and place remote connections behind virtual private networks. If an appliance has already suffered compromise, administrators should disconnect the hardware from local networks to halt data encryption, avoid paying extortion ransoms, and restore clean data from safe offline backups.

How the Synology warns of C3RB3R ransomware attacks issue works

The intrusion process relies on automated scanners identifying exposed management interfaces and triggering unpatched weaknesses in DiskStation Manager. Attackers exploit vulnerabilities such as CVE-2024-10441 for remote code execution, alongside CVE-2024-50629 for arbitrary file reads and CVE-2024-10445 for arbitrary file writes. Chaining these vulnerabilities allows threat actors to bypass authentication checks and run arbitrary code on the underlying storage appliance. Because the compromise targets foundational software flaws, attackers do not need valid administrative user credentials to execute malicious operating system payloads.

Once executed, the ransomware encrypts user files, renames them with a .L0CK3D extension, and drops an extortion document named read-me3.txt in targeted directories. The note claims third-party decryption attempts will prove fatal to data and offers one free file decryption on its dark web portal to verify capability. The malware traces its lineage to the 2016 Cerber ransomware-as-a-service operation, which accounted for over 80 percent of ransomware attacks before vanishing in 2019. It resurfaced in December 2021 as C3RB3R, targeting Atlassian Confluence and GitLab before hitting storage hardware.

What is still unknown about Synology warns of C3RB3R ransomware attacks

Several critical technical and operational details regarding the ongoing attacks remain undisclosed. Synology has not specified which exact vulnerability among the December 2024 patches is being exploited as the initial access vector in current incidents. Furthermore, when reporters sought additional information regarding attack distribution or victim statistics, a Synology spokesperson was not immediately available to comment. Public reports have not clarified how many storage devices have been compromised or how many affected owners paid ransom demands through the dark web payment portal.

Broad visibility gaps also obscure the security posture of Internet-exposed devices. Although Shadowserver reports tracking over 380,000 Internet-exposed Synology NAS devices, its data does not indicate how many appliances have installed security updates or operate as honeypots. Additionally, researchers have not confirmed whether the threat group consists of original members from the 2016 Cerber syndicate or separate actors deploying recycled code. Until further forensic telemetry emerges, administrators must assume any unpatched, Internet-exposed appliance is under active automated probing across the web.