Hiddentear
Table of Contents
Overview
Ransom:Win32/Hiddentear is a highly significant ransomware family in cybersecurity history. Originally developed by a Turkish researcher in 2015 and released on GitHub as an 'open-source educational project', HiddenTear was intended to demonstrate how ransomware works. Predictably, it was immediately co-opted by script kiddies and low-tier cybercriminals, who slightly modified the source code to spawn hundreds of real-world ransomware variants, causing widespread damage.
Understanding HiddenTear
To a victim, a HiddenTear infection is indistinguishable from top-tier ransomware; their files are encrypted, a unique extension (e.g., `.locked`) is appended, and a ransom note demands Bitcoin. For a security analyst, a HiddenTear detection often indicates a less sophisticated adversary. Because the original source code was flawed—specifically, the random number generator used for the encryption keys was extremely weak—files encrypted by many early HiddenTear variants can actually be decrypted for free using publicly available tools.
Execution and Encryption Mechanics
Because the source code is public, the distribution vector varies wildly, ranging from spam emails (`T1566.001`) to malicious Discord links (`T1189`). Upon execution (`T1204.002`), the malware typically establishes persistence by dropping a copy of itself in the `%AppData%` or `%LocalAppData%` directory and creating a Registry Run key (`T1547.001`). The core encryption routine targets a hardcoded list of file extensions (documents, images, databases) using AES encryption (`T1486`). In the original code, the encryption key was sent in plaintext to a web server via an HTTP GET request (`T1041`). It then drops a simple text file (`READ_IT.txt`) on the desktop detailing the ransom demand.
Indicators of Compromise & Impact
The impact is significant data loss and disruption. The primary IoC is the sudden renaming of files to include anomalous extensions (which vary wildly depending on the script kiddie who compiled it) and the appearance of the ransom note. Network analysts might observe an HTTP GET request containing a string of characters (the AES key) being sent to a suspicious, often free-hosting, web domain. Static analysis of the executable will often reveal it is compiled in .NET and heavily resembles the public GitHub repository.
MITRE ATT&CK Techniques
Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:
| Technique | Name | Tactic | Official Spec |
|---|---|---|---|
T1486 | Data Encrypted for Impact | Impact | ATT&CK ↗ |
T1547.001 | Boot or Logon Autostart Execution: Registry Run Keys | Persistence | ATT&CK ↗ |
T1041 | Exfiltration Over C2 Channel (Sending the AES key) | Exfiltration | ATT&CK ↗ |
T1204.002 | User Execution: Malicious File | Execution | ATT&CK ↗ |
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-FEA | File Execution Analysis | Harden | T1204.002 | Enforce AppLocker and Windows Defender Application Control (WDAC) to block executable launches from temporary and user-writable directories. |
D3-FAED | File Alteration Early Detection | Detect | T1486 | Deploy canary files and monitor mass rename/encryption I/O spikes to terminate ransomware threads immediately. |
D3-RPM | Registry Persistence Monitoring | Detect | T1547.001 | Audit and restrict write privileges to user and machine-level Registry Run/RunOnce keys using Endpoint Privilege Management. |
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_HIDDENTEAR_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Hiddentear"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "hiddentear" 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 - Hiddentear (Ransomware) Execution & Triage
id: 16698cf2-4b7a-5158-b92e-45e819b77c46
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Hiddentear 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/hiddentear
- 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.t1486
- attack.t1547_001
- attack.t1041
- attack.t1204_002
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_HIDDENTEAR_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Hiddentear 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 = "hiddentear" 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.
- Instantly isolate the infected endpoint from the network to halt the encryption process, specifically protecting mapped network shares.
- Do NOT reboot the machine immediately; capture a live memory dump (RAM) first, as poorly coded variants often leave the AES key in memory.
- Crucially, identify the specific variant of HiddenTear (based on the extension and ransom note) and check 'NoMoreRansom.org'; a vast majority of these variants have free decryption tools available.
- If no decryptor is available, restore the affected systems from secure, offline backups.
What to Avoid
Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.
- Do not pay the ransom. HiddenTear operators are often inexperienced script kiddies who frequently lose the C2 infrastructure or the keys, meaning paying rarely results in file recovery.
- Avoid assuming the encryption is unbreakable; the cryptographic flaws in the original source code persist in many wild variants.
References & External Analysis
- Search "hiddentear" on VirusTotal (External Analysis)
- Search "hiddentear" on Any.Run (Sandbox Sandbox)
- Search "hiddentear" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Hiddentear and what threat category does it belong to?
Hiddentear 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 Hiddentear establish persistence and evade defensive controls?
Hiddentear 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 Hiddentear compromise?
Security teams responding to Hiddentear 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 Hiddentear employ during execution?
Hiddentear 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 Hiddentear, and what is the recommended recovery procedure?
Decryption availability for Hiddentear 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 Hiddentear Ransomware from Windows?
Manual removal of Hiddentear 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 Hiddentear a virus or a Ransomware?
Hiddentear is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Hiddentear typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Hiddentear infection?
Symptoms of Hiddentear 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 Hiddentear 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.