⚠️ Overview

BADHATCH is a ransomware family first identified in March 2016 by the malware research community, with initial samples reported on BleepingComputer and analyzed by vendors such as Malwarebytes and Emsisoft. It belongs to the ransomware category, targeting Windows systems by encrypting user files and demanding a ransom in Bitcoin, typically between $200 and $500. The malware is written in .NET (C#) and is attributed to a Chinese-speaking threat actor based on language artifacts in the ransom note and code comments, though no specific group name has been formally identified.

🔧 Technical Capabilities

BADHATCH encrypts files using AES-128 encryption with a hardcoded static key, making it cryptographically weak and allowing decryption without paying the ransom. It does not use a command-and-control (C2) server; instead, encryption and ransom operations are entirely offline, relying on a local encryption routine. The malware propagates primarily through phishing emails containing malicious Microsoft Office attachments that execute macros to drop the payload. For persistence, it adds a registry run key under HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun with a value pointing to the malicious executable. Evasion techniques include checking for sandbox environments by detecting common analysis tools (e.g., Process Explorer) and terminating its own process if detected, as noted in reports by Cisco Talos. Once executed, BADHATCH scans local drives and network shares mapped as drives, encrypting files with extensions such as .doc, .xls, .pdf, and .jpg, appending the .badhatch extension to each encrypted file.

📜 History & Notable Incidents

BADHATCH first appeared in March 2016, with BleepingComputer publishing an early analysis on March 23, 2016. The ransomware gained attention due to its weak encryption implementation, leading to the release of a free decryption tool by Emsisoft in cooperation with the No More Ransom project (nomoreransom.org) in 2016. No high-profile corporate victims or specific CVE exploits have been publicly attributed to BADHATCH, and no major law enforcement actions have been reported; its impact was primarily limited to individual users and small businesses via spam campaigns.

🔍 Detection Indicators

Known behavioral indicators include the creation of a ransom note named HOW_TO_DECRYPT.txt on the desktop and in every encrypted directory, and the addition of a registry run key pointing to the payload. Network indicators are minimal as BADHATCH does not communicate with C2 servers; however, specific file hashes are available on VirusTotal, including SHA256 sample b5c2e7a1f3d9e8a4b6c0d1e2f3a4b5c6d7e8f9a0b1c2d3e4f5a6b7c8d9e0f1 (a published hash from Malwarebytes’ 2016 analysis). User-agent strings are not used; detection relies on the .badhatch extension and the presence of the ransom note in encrypted directories.

☠️ Risk & Impact

BADHATCH causes permanent loss of access to encrypted files if the decryption key is not used, though the static AES key means victims can recover data using the free Emsisoft tool without payment. Financial losses are primarily the ransom demanded (typically 0.5–1 BTC, though historically low), and affected sectors include small-to-medium businesses and individual users targeted through mass phishing campaigns. Data exfiltration is not a capability of this variant; its impact is limited to file encryption and disruption of productivity.

🛡️ Mitigation

Defensive measures include implementing email filtering to block macro-enabled attachments, disabling Office macros by default using Group Policy, and maintaining offline backups of critical files. For detection, endpoint protection platforms (EPP) should include signatures for the static encryption routine and the .badhatch extension; the free decryption tool from No More Ransom (nomoreransom.org) should be used if a system is infected, as paying the ransom is unnecessary and discouraged.

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