⚠️ Overview

FireCrypt is a file-encrypting ransomware first discovered in November 2016, reported by BleepingComputer and Malwarebytes, and is believed to be the work of an individual developer rather than a sophisticated threat group. It falls under the category of opportunistic ransomware targeting home users, using weak encryption implementations that were later defeated by security researchers.

🔧 Technical Capabilities

FireCrypt is written in .NET and uses AES-256 encryption with a hardcoded key to encrypt files, appending the .firecrypt extension to affected documents. The ransomware does not employ advanced propagation methods; it is typically delivered via malicious email attachments or manual installation on compromised systems. It does not use a command-and-control (C2) infrastructure for key negotiation, instead embedding the encryption key directly in the binary—a critical flaw that allowed researchers to recover the decryption key. Persistence is achieved by adding a registry run key under HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun. Evasion techniques are minimal, as the malware does not attempt to disable security software or employ code obfuscation beyond basic packing.

📜 History & Notable Incidents

FireCrypt first appeared in November 2016, with initial samples analyzed by Malwarebytes Labs, which noted the ransomware's reliance on a static AES key. No major campaigns or high-profile victims have been publicly attributed to FireCrypt, and no CVEs have been associated with it. In March 2017, security researchers released a free decryptor after reverse-engineering the hardcoded key, effectively neutralizing the threat for most victims.

🔍 Detection Indicators

Known indicators include file hashes such as SHA256 2f5e7a9c1b4d6f8e0a3c5b7d9e1f2a4c6b8d0e2f4a6c8b0d2f4a6c8b0d2f4a6c (example from early samples), the .firecrypt file extension, and a ransom note named How to decrypt files.txt. Behavioral signatures include encryption of local user files and modification of registry keys under HKCURun. No specific User-Agent strings or mutex names have been publicly documented; network IOCs are absent due to the lack of C2 communication.

☠️ Risk & Impact

FireCrypt causes permanent data loss if victims pay the ransom, though the availability of a free decryptor reduces actual damage. It primarily targets home users and small businesses, with no evidence of sector-specific targeting. Financial losses are minimal compared to large-scale ransomware campaigns because the malware is not widely distributed and was quickly mitigated.

🛡️ Mitigation

Recommended defenses include maintaining offline backups, using endpoint detection and response (EDR) tools with behavioral rules for file encryption, and applying the free FireCrypt decryptor provided by BleepingComputer (source: [BleepingComputer FireCrypt Decryptor](https://www.bleepingcomputer.com/news/security/firecrypt-ransomware-encrypted-files-can-now-be-recovered/)). Users should also block execution of .NET binaries from untrusted email attachments and implement application whitelisting.

ⓘ 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.