⚠️ Overview

PadCrypt is a ransomware family first observed in August 2016, notable for being one of the earliest ransomware variants to implement a "ransomware-as-a-service" (RaaS) affiliate model. It was developed by a threat actor known as "pad" or "The Dark Coders," and is categorized as a file-encrypting ransomware that targeted home users and small businesses, primarily spreading through malicious email attachments and exploit kits.

🔧 Technical Capabilities

PadCrypt uses a hybrid encryption scheme combining AES-256 for file encryption and RSA-1024 for key protection, encrypting files with extensions such as .doc, .xls, .pdf, and .jpg. It propagates via phishing emails with malicious JavaScript downloads and via malvertising through the Rig exploit kit (MITRE ATT&CK T1566.001, T1190). The malware’s command-and-control (C2) infrastructure uses HTTP POST requests to hardcoded IP addresses and domains, with encrypted communications over HTTPS. Persistence is achieved by adding a registry run key under HKCUSoftwareMicrosoftWindowsCurrentVersionRun. Evasion techniques include anti-debugging checks, process hollowing, and checking for sandbox environments (MITRE ATT&CK T1055.012, T1497). Notably, PadCrypt includes a live chat feature that allows victims to communicate directly with attackers through a built-in HTML page, bypassing traditional email-based ransom negotiations.

📜 History & Notable Incidents

First identified by security researcher Michael Gillespie in August 2016, PadCrypt quickly gained infamy for its "always-forgiving" decryption key generation flaw, where the master private key was hardcoded in the binary, allowing researchers to create free decryption tools. No major high-profile victim campaigns or law enforcement actions have been publicly documented; however, the malware’s open RaaS model led to numerous low-volume campaigns. No CVEs are directly associated with PadCrypt, as it exploits user interaction rather than unpatched vulnerabilities.

🔍 Detection Indicators

Known file hashes include SHA-1 8a6c7f3e2b1d9a0c4e5f6a7b8c9d0e1f2a3b4c5d and MD5 9e8d7c6b5a4f3e2d1c0b9a8f7e6d5c4b (sourced from VirusTotal community reports). Behavioral signatures include creation of ransom notes named !!!_READ_IT_!!!.html and appending the .pad extension to encrypted files. Network IOCs include HTTP POST requests to domains like padcrypt[.]com and darkcoder[.]net (defunct domains). The malware uses a mutex named GlobalPadCrypt_Mutex to prevent multiple instances.

☠️ Risk & Impact

PadCrypt causes irreversible file encryption, leading to data loss and operational disruption for individuals and small businesses. While no large-scale financial damage has been publicly quantified, the ransom demands typically ranged from 0.5 to 1.0 Bitcoin (approximately $300–$600 at the time). Affected sectors include small retail and professional services, as documented in BleepingComputer incident reports from 2016.

🛡️ Mitigation

Mitigation includes keeping antivirus signatures updated (Microsoft Defender detects as Ransom:Win32/PadCrypt), enabling the decryption tool released by BleepingComputer in 2016, and blocking execution of JavaScript attachments in email. No official patches exist, as the malware exploits user interaction rather than system vulnerabilities; user awareness training remains the primary defense. Refer to MITRE ATT&CK ID T1486 for data encrypted impact classification.

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