Hiddentears

Overview

Ransomware:Win32/Hiddentears is a highly significant case study in malware history. It was originally released on GitHub in August 2015 by a Turkish programmer as an 'educational' open-source ransomware project. Predictably, it was immediately weaponized by low-skill threat actors ('script kiddies'), spawning hundreds of real-world ransomware variants (like MoWare, Cryptear, and KryptoLocker). It demonstrates the extreme danger of publishing destructive code, regardless of intent (`T1486`).

Understanding Hiddentears (Open-Source Ransomware)
To an end-user, a HiddenTears-based infection looks like standard ransomware: files are encrypted, extensions are changed (often to `.locked` or `.hiddentears`), and a text-based ransom note appears on the desktop. For an incident response team, identifying a variant as based on HiddenTears is often a relief, as the original encryption implementation contained fatal flaws that allow for free decryption.

Execution and Cryptographic Flaws
HiddenTears variants are typically distributed via low-effort malspam or dropped by other generic trojans. Upon execution, it scans the user's directories and uses AES-256 encryption (`T1486`) to lock specific file types. It communicates the encryption key to a C2 server (often a simple web panel) (`T1041`). Crucially, the original open-source code utilized a fundamentally flawed method for generating the AES key and Initialization Vector (IV). It used the standard `Random` class seeded with a predictable timestamp, allowing cryptographic researchers to easily brute-force the seed and reverse the encryption without paying the ransom.

Indicators of Compromise & Impact
The primary impact is data unavailability. Host-based IoCs include files appended with unusual extensions, the presence of ransom notes (often named `READ_IT.txt` or similar), and high CPU utilization by an unknown process during the encryption phase. A key indicator of a HiddenTears variant is often the presence of specific hardcoded strings from the original open-source project within the executable's memory.

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the MITRE ATT&CK framework:

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.

Generated Detections (Boilerplate)

These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.

YARA Rule

rule MALWARE_WIN_HIDDENTEARS {
    meta:
        description = "Detects Hiddentears (ransomware)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "hiddentears" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Hiddentears Activity
id: af55f0d816d7167ef5f209646623f557
status: experimental
description: Detects generic indicators of the hiddentears malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*hiddentears*"
    condition: selection
level: medium

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Immediately disconnect the infected machine from the network to prevent the ransomware from reaching network shares.
2. Do not pay the ransom. Immediately search reputable security vendor sites (like NoMoreRansom) for a HiddenTears decryptor tool.
3. Preserve the infected system in its current state; rebooting might destroy artifacts needed by the free decryption tools.
4. Identify and patch the initial entry vector (often weak RDP credentials or malicious email attachments).

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not assume the data is lost forever; HiddenTears is notoriously flawed, and free decryption tools are widely available.
2. Avoid paying the ransom; dealing with script kiddies using open-source tools rarely results in successful decryption.

References & External Analysis

• Search "hiddentears" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: ransomware)

Explore other malware families in the same category:

• Spora
• Shadowbrokers
• Hexzone
• Primawega
• Trafog

Machine-readable

Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/hiddentears.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.