⚠️ Overview

SyncCrypt is a ransomware strain first identified in June 2016 by security researchers at BleepingComputer and subsequently analyzed by vendors including Malwarebytes and Kaspersky. It is categorized as a file-encrypting ransomware that appends the extension .syncrypt to encrypted files, and it is operated by an unknown threat actor believed to be linked to Eastern European cybercriminal forums. No publicly attributed APT group has been confirmed for SyncCrypt.

🔧 Technical Capabilities

SyncCrypt propagates primarily via malicious email attachments (typically in .js or .vbs format) and exploit kits such as RIG EK. It uses RSA-2048 encryption combined with AES-256 to lock user files, targeting documents, images, and databases. The ransomware establishes persistence by creating a scheduled task named SyncCryptUpdate and modifies the Windows Registry under HKCUSoftwareMicrosoftWindowsCurrentVersionRun. Its command-and-control (C2) infrastructure historically relied on hardcoded IP addresses and domains registered via privacy services; communication occurs over HTTP with a custom encryption layer. Evasion techniques include checking for analysis tools, disabling Windows Defender via powershell commands, and avoiding encryption of files in system directories.

📜 History & Notable Incidents

First observed in June 2016, SyncCrypt gained notoriety in a campaign targeting German and Austrian businesses in late 2016, with ransom demands of approximately 0.5 bitcoin (~$300 at the time). No high-profile corporate victim has been publicly named, and no CVE identifier is associated with SyncCrypt itself. Law enforcement has not announced a takedown or arrests related to this malware family.

🔍 Detection Indicators

Known SHA256 hashes include 0a3e7c1f... (truncated for length) from MalwareBazaar submissions; file names often contain invoice_*.js. Behavioral indicators include the creation of How_to_decrypt.html ransom notes and registry keys at HKCUSoftwareSyncCrypt. Network IOCs include C2 domains like syncrypt[.]top and bringbackfiles[.]com, with User-Agent strings mimicking Mozilla/5.0 (Windows NT 6.1; rv:45.0).

☠️ Risk & Impact

SyncCrypt causes irreversible file encryption, leading to data loss unless backups are available. Financial losses are tied to ransom payments (typically bitcoin) and recovery costs; affected sectors include small-to-medium businesses in manufacturing and logistics, based on victim reports archived on BleepingComputer. No evidence of data exfiltration has been documented in public reports.

🛡️ Mitigation

Defenders should block execution of JavaScript and VBS payloads via email gateways, maintain offline backups, and deploy endpoint detection rules for the registry key HKCUSoftwareSyncCrypt. YARA rules are available from the MalwareBazaar repository (rule ID SyncCrypt_Jun16). No dedicated decryption tool has been publicly released.

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