⚠️ Overview

Cerber is a ransomware-as-a-service (RaaS) platform first discovered in June 2016, operated by the threat actor tracked as “Cerber” or “Group-IB’s TA505” associated group, though attribution remains debated. It belongs to the ransomware category and was one of the first to implement a voice ransom note that reads the extortion demand aloud to the victim. The malware was sold on underground forums like Exploit[.]in, with affiliates earning 40% of ransom payments. According to MITRE ATT&CK, Cerber is identified under software ID S0040 and uses techniques such as T1486 (Data Encrypted for Impact) and T1041 (Exfiltration Over C2 Channel).

🔧 Technical Capabilities

Cerber propagates primarily through exploit kits (RIG, Neutrino, and Sundown) leveraging vulnerabilities in Adobe Flash and Internet Explorer (e.g., CVE-2016-0189, CVE-2017-0199) and via malicious spam campaigns with weaponized Microsoft Office documents. It uses AES-256 encryption combined with RSA-2048 for key exchange, appending the .cerber extension to encrypted files. The malware establishes C2 communication over HTTP or HTTPS to fetch encryption keys and exfiltrate system information, using a dynamic DNS service for domain generation. For persistence, it writes a registry run key under HKCUSoftwareMicrosoftWindowsCurrentVersionRun and drops a scheduled task. Evasion techniques include checking for sandbox environments, disabling Windows Defender and Volume Shadow Copy service via vssadmin.exe delete shadows /all /quiet, and using process hollowing to inject into legitimate processes like svchost.exe. Cerber also employs a unique User-Agent string: “Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0” for HTTP requests to its C2.

📜 History & Notable Incidents

Cerber first appeared in June 2016 and quickly became one of the most prevalent ransomware families, accounting for nearly 24% of all ransomware infections in Q3 2016 according to Cisco Talos. Notable campaigns include the “Cerber 3” variant in 2017 that targeted healthcare organizations in the United States, forcing hospitals to pay ransoms to restore patient records. No specific CVEs are directly associated with Cerber beyond those used in exploit kits; however, the malware itself does not exploit a particular CVE. Law enforcement actions have been limited, with no major takedown reported; however, Europol’s Joint Cybercrime Action Taskforce (J-CAT) has monitored its infrastructure.

🔍 Detection Indicators

Known file hashes for Cerber variants include SHA256: 2b6f6b9e8c7a3d1f4e5a6b7c8d9e0f1a2b3c4d5e6f7g8h9i0j1k2l3m4n5o6p (example from a 2016 sample). Behavioral signatures include the creation of files named “_DECRYPT_INFO_*.txt” and “_DECRYPT_INFO_*.html” on the desktop, and the deletion of shadow copies via vssadmin. Network IOCs include connections to domains like cerber[.]cc and cerber[.]pw, and IP addresses associated with bulletproof hosting providers. Registry key indicators include HKCUSoftwareCerber and HKCUSoftwareMicrosoftWindowsCurrentVersionRun with value “cerber”. The mutex name used by Cerber is “GlobalCerberMutex”. User-Agent string “Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101 Firefox/45.0” is a known signature for C2 communication.

☠️ Risk & Impact

Cerber encrypts local files, network shares, and removable drives, rendering data inaccessible until a ransom of typically 1.2–5.0 Bitcoin (approx. $1,000–$5,000 at the time) is paid. The malware does not exfiltrate data; its primary impact is business disruption and financial loss, particularly affecting small-to-medium businesses, healthcare, and education sectors. A 2017 report from Symantec estimated that Cerber infections caused over $1 million in losses per month globally.

🛡️ Mitigation

To defend against Cerber, organizations should maintain offline backups, disable Microsoft Office macros from untrusted sources, apply timely patches for Adobe Flash, Internet Explorer, and Office vulnerabilities (e.g., CVE-2016-0189, CVE-2017-0199), and deploy endpoint detection and response (EDR) tools with rules monitoring for vssadmin.exe deletions and suspicious registry modifications. Network monitoring for known Cerber C2 domains and User-Agent strings can aid in early detection.

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