Hiddentears
Table of Contents
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 our technical analysis hubs and the official 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.
MITRE D3FEND™ Defensive Countermeasures
Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):
| D3FEND ID | Countermeasure Name | Tactic | Countered ATT&CK | Defensive Guidance |
|---|---|---|---|---|
D3-EAF | Egress Analysis and Filtering | Isolate | T1041 | Enforce perimeter TLS inspection and alert on anomalous outbound data volume ratios transmitting over active C2 channels. |
D3-PBA | Process Spawn Analysis | Detect | T1059.003 | Inspect command-line arguments and anomalous parent-child relationships spawning from cmd.exe. |
D3-FAED | File Alteration Early Detection | Detect | T1486 | Deploy canary files and monitor mass rename/encryption I/O spikes to terminate ransomware threads immediately. |
Tiered Detection Rules (Cisco CAIRN Model)
Modern threat detection requires multi-layered rule engineering. We classify detections into three operational tiers based on signal fidelity:
Tier 1 Primitive Artifact Rule (Fast Triage)
Matches raw strings and file markers. Vulnerable to binary repacking and simple obfuscation.
rule MALWARE_WIN_HIDDENTEARS_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Hiddentears"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "hiddentears" ascii wide nocase
condition:
uint16(0) == 0x5a4d and any of them
}Tier 2 Behavioral Context Rule (Process Chains & Sigma)
Tracks parent-child process anomalies and suspicious scripting telemetry. Resilient against file renames.
title: SystemHelpDesk Detection - Hiddentears (Ransomware) Execution & Triage
id: 03ecacd1-253a-52dc-b3ec-63ce2198b26c
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Hiddentears malware family. Detects volume shadow copy deletion, boot status
tampering, and recovery inhibition characteristic of modern ransomware operations.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/hiddentears
- https://malware-families-catalog.systemhelpdesk.com/defensive/ransomware-protection
- https://malware-families-catalog.systemhelpdesk.com/
author: Ricky Jordan, Lead Threat Intelligence Analyst, SystemHelpDesk MSP
date: '2026-10-14'
modified: '2026-10-14'
tags:
- attack.ransomware
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1041
- attack.t1486
- attack.t1059_003
logsource:
category: process_creation
product: windows
detection:
selection_process:
Image|endswith:
- \vssadmin.exe
- \wmic.exe
- \wbadmin.exe
- \bcdedit.exe
CommandLine|contains:
- delete shadows
- shadowcopy delete
- resize shadowstorage
- recoveryenabled no
- ignoreallfailures
condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: criticalTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_HIDDENTEARS_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Hiddentears tradecraft"
tier = "T3 - Attribution Fingerprint"
confidence = "High (Confirmed Family Signature)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
// Core family identifier & heuristic payload signatures
$attrib_str = "hiddentears" ascii wide nocase
$pe_magic = "MZ" ascii
$net_marker = "http" ascii nocase
condition:
uint16(0) == 0x5a4d and ($attrib_str and $net_marker) and filesize < 15MB
}Containment & Response Steps
Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.
- Immediately disconnect the infected machine from the network to prevent the ransomware from reaching network shares.
- Do not pay the ransom. Immediately search reputable security vendor sites (like NoMoreRansom) for a HiddenTears decryptor tool.
- Preserve the infected system in its current state; rebooting might destroy artifacts needed by the free decryption tools.
- 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.
- Do not assume the data is lost forever; HiddenTears is notoriously flawed, and free decryption tools are widely available.
- 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)
- Search "hiddentears" on Any.Run (Sandbox Sandbox)
- Search "hiddentears" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Hiddentears and what threat category does it belong to?
Hiddentears is classified as a Ransomware. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments.
How does Hiddentears establish persistence and evade defensive controls?
Hiddentears typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks.
What are the essential incident response steps for mitigating a Hiddentears compromise?
Security teams responding to Hiddentears should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups.
What cryptographic algorithms and file targeting techniques does Hiddentears employ during execution?
Hiddentears typically leverages hybrid cryptographic architectures combining symmetric stream or block ciphers (such as AES-256 or ChaCha20) for rapid file encryption with asymmetric algorithms (such as RSA-2048 or Curve25519) to securely protect the session keys. It aggressively targets sensitive file extensions including corporate documents, databases, virtual disks, and backups while systematically executing commands to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) and disable system recovery options.
Are decryptors available for Hiddentears, and what is the recommended recovery procedure?
Decryption availability for Hiddentears depends on whether security researchers or law enforcement (such as the No More Ransom initiative) have recovered the master private keys or discovered flaws in its key generation routines. Victims should never pay the extortion demand, as payment fuels criminal operations without guaranteeing file restoration. The recommended recovery procedure entails isolating infected hosts, conducting forensic disk imaging, identifying the root access vector, and restoring validated systems from immutable offline backups.
How do I remove the Hiddentears Ransomware from Windows?
Manual removal of Hiddentears is highly discouraged as it may leave persistence mechanisms intact. We recommend disconnecting the device from the internet and utilizing a professional incident response service or enterprise-grade EDR software to conduct a full forensic sweep.
Is Hiddentears a virus or a Ransomware?
Hiddentears is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Hiddentears typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Hiddentears infection?
Symptoms of Hiddentears can include unexpected system slowness, unauthorized outbound network traffic to unknown IP addresses, disabled security software, and suspicious background processes running from AppData or Temp directories.
Protect Your Network Against Ransomwares
Want to prevent Hiddentears and similar threats from compromising your organization? Read our comprehensive defensive guide: Ransomware Containment & Incident Response.
📣 Threat Intel Correction or Update?
Notice an outdated IOC, unlisted alias, or disputed attribution? Threat researchers are invited to propose an update on GitHub or contact the SystemHelpDesk research desk. All community revisions are credited in our public CHANGELOG.
Machine-readable
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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.