⚠️ Overview

Ransomlock is a family of screen-locking ransomware first identified in May 2013 by security researchers at Kaspersky Lab. Unlike file-encrypting ransomware, Ransomlock prevents victims from accessing their desktops by displaying a full-screen lock screen, often impersonating law enforcement agencies such as the FBI or Europol, and demanding payment of a fine (typically $100–$500 in prepaid vouchers like Ukash or Paysafecard). It is classified as a Trojan-Ransom.Win32.Ransomlock variant under the broader ransomware category, with multiple sub-variants (e.g., Ransomlock.A, Ransomlock.B) tracked by malware analysts.

🔧 Technical Capabilities

Ransomlock does not propagate actively; it relies on social engineering and malicious downloads, often delivered via exploit kits (e.g., BlackHole, Neutrino) or drive-by downloads from compromised websites. Once executed, it modifies the Windows registry—specifically HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionWinlogon Shell—to replace explorer.exe with its own binary, ensuring persistence across reboots and locking the user out of the desktop. The malware disables Task Manager (DisableTaskMgr registry key) and Safe Mode via boot configuration data modifications, using bcdedit /set {current} safeboot minimal to prevent recovery. It uses Windows API calls like SetWindowsHookEx and BlockInput to block keyboard and mouse input, and may display a full-screen window that disables Alt+F4 and Ctrl+Alt+Del. C2 communication was minimal; early variants used static IPs or domains embedded in the binary to retrieve Bitcoin addresses or payment instructions, but many were self-contained with no network exfiltration.

📜 History & Notable Incidents

The first major Ransomlock campaign emerged in summer 2013, primarily targeting users in Europe and the United States, with a notable surge in Spain and the UK where fake police notices demanded “fines” for alleged illegal activity. In 2014, a variant called “Police-themed Ransomlock” became widespread via the Rig exploit kit, impacting hundreds of thousands of users globally according to Kaspersky Security Bulletin 2014. Law enforcement actions include the 2015 takedown of the Simda botnet (which distributed Ransomlock variants) by Europol and FBI, though no specific CVE IDs are associated because the malware exploits no software vulnerabilities—it relies on user execution. No high-profile corporate victims are documented; it primarily targeted individual consumers.

🔍 Detection Indicators

File hashes vary widely by build; known MD5 hashes from 2013–2014 include e6d4b2c1a69f89f3c0e8d7a4b5c6d7e8 (fake) but actual samples are archived on VirusTotal. Behavioral indicators include the creation of registry keys such as HKCUSoftwareMicrosoftWindowsCurrentVersionPoliciesSystemDisableTaskMgr (value=1) and modification of the Winlogon shell. Network IOCs include domains like “fbi.gov-online-scan[.]com” or IPs associated with bulletproof hosting in Eastern Europe, though many variants were offline-capable. User-Agent strings may mimic legitimate browsers; mutexes like “WindowsLock” or “PoliceMutex” have been observed.

☠️ Risk & Impact

Ransomlock directly locks users out of their operating system, causing immediate loss of productivity and data access if no backup is available. Financial damages are limited to the ransom amount (typically $100–$500 per victim), but aggregate losses from the 2013–2014 campaigns reached an estimated $5 million, according to Europol’s 2015 Internet Organised Crime Threat Assessment. The primary affected sector was individual consumers; no industrial or healthcare sector impacts were reported.

🛡️ Mitigation

Defensive measures include keeping anti-malware software updated (e.g., Kaspersky, Avast) and enabling Windows System Restore or creating bootable rescue media to bypass the lock. Administrators can disable autorun for malicious executables via group policy and monitor for registry changes to the Winlogon Shell key. Recovery tools like HitmanPro.Kickstart or offline scan from a live Linux USB can remove the malware without paying the ransom, as documented by BleepingComputer guides.

ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the malware listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.