Chimera
Table of Contents
Overview
Executive Summary
Chimera is a highly aggressive strain of enterprise ransomware that pioneered the "double extortion" tactic. It not only encrypts the victim's critical data, halting business operations, but it also actively exfiltrates sensitive files to attacker-controlled servers before encryption begins. The threat actors then threaten to publish this confidential data (intellectual property, customer records, financial data) on public "leak sites" if the ransom is not paid, significantly increasing the pressure on the victim organization.Infection Vector and Technical Capabilities
Chimera typically infiltrates networks via highly targeted spear-phishing campaigns delivering malicious payloads (often utilizing exploits like those found in the Angler Exploit Kit) or by brute-forcing weakly secured Remote Desktop Protocol (RDP) servers. Once inside the network, it executes a devastating two-pronged attack:- Data Exfiltration (The First Extortion): Before encrypting anything, Chimera maps the network and silently uploads high-value files to external cloud storage or FTP servers controlled by the attackers.
- Rapid Encryption (The Second Extortion): It utilizes strong cryptography (AES+RSA) to encrypt user files and network shares, appending a `.crypt` extension. It actively deletes Volume Shadow Copies (`vssadmin.exe Delete Shadows`) to prevent easy data restoration.
- Psychological Pressure: The ransom note explicitly states that data has been stolen and will be published if the cryptocurrency demand is not met, creating a severe GDPR/compliance crisis alongside the operational outage.
Threat Assessment
A Chimera infection is a catastrophic security and public relations incident. It poses an existential threat to the organization through severe data loss, extended downtime, guaranteed regulatory fines (due to the data breach aspect), and immense reputational damage.Incident Response and Remediation
- Immediate Network Segmentation: Instantly sever the network connection of all infected machines to halt the lateral movement and, crucially, stop any ongoing data exfiltration.
- Data Breach Protocol: Because Chimera exfiltrates data, this incident must be immediately treated as a major data breach. Engage legal counsel and prepare for mandatory regulatory disclosures (e.g., GDPR, CCPA). Do not attempt to negotiate without professional IR guidance.
- Eradication and Recovery: Eradicating ransomware requires a complete infrastructure rebuild. All affected machines must be wiped to bare metal and rebuilt from known-good, offline backups. All enterprise credentials must be rotated globally.
Known aliases
Threat reports may refer to this family under multiple names:
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 ↗ |
T1048 | Exfiltration Over Alternative Protocol | Exfiltration | ATT&CK ↗ |
T1490 | Inhibit System Recovery (Behaviorally blocking the deletion of backups) | Impact | 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-NDF | Network Data Filtering | Isolate | T1048 | Inspect non-standard port traffic and block unauthorized ICMP or DNS tunneling protocols at the network perimeter. |
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-VSS | Volume Shadow & Snapshot Hardening | Harden | T1490 | Block execution of vssadmin.exe and wmic shadowcopy delete; maintain air-gapped immutable backup repositories. |
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_CHIMERA_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Chimera"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "chimera" ascii wide nocase
$s2 = "ransomware.chimera" ascii wide nocase
$s3 = "trojan-ransom.win32.chimera" ascii wide nocase
$s4 = "extortion.chimera" 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 - Chimera (Ransomware) Execution & Triage
id: 77ca126f-88eb-5726-8337-c5f1500fc722
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Chimera 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/chimera
- 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.t1048
- attack.t1490
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_CHIMERA_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Chimera 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 = "chimera" 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 isolate affected host(s) from the internal network (disconnect physical Ethernet and disable Wi-Fi/Bluetooth) to prevent Chimera from spreading laterally or encrypting network-attached storage (NAS) and shared SMB volumes.
- Preserve volatile system memory (RAM capture) on a representative endpoint before attempting a reboot or power-down, as Chimera symmetric encryption keys or uncompiled payload components may still reside in memory.
- Audit process execution logs and terminate active scripting interpreters (e.g. PowerShell, CMD, WScript) or commands executing 'vssadmin.exe delete shadows' or 'wbadmin' used by Chimera to inhibit recovery.
- Investigate the initial compromise vector (such as exposed RDP instances, spearphishing attachments, or vulnerable edge gateways) and enforce an immediate credential reset for all compromised Active Directory accounts.
- Restore critical assets and databases exclusively from verified, air-gapped, or immutable offline backups once the Chimera binary and related persistence hooks are eradicated.
What to Avoid
Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.
- Do not restart or power cycle infected systems prematurely; doing so destroys volatile RAM encryption keys and may trigger bootloader locking logic embedded in Chimera.
- Avoid negotiating or paying the extortion demand without prior forensic evaluation and consultation with incident response specialists, as payment does not guarantee data recovery.
- Do not connect clean backup drives or external storage to the affected network until Chimera eradication is completely verified.
References & External Analysis
- Search "chimera" on VirusTotal (External Analysis)
- Search "chimera" on Any.Run (Sandbox Sandbox)
- Search "chimera" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Chimera and what threat category does it belong to?
Chimera 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 Chimera establish persistence and evade defensive controls?
Chimera 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 Chimera compromise?
Security teams responding to Chimera 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 Ransomware.Chimera employ during execution?
Ransomware.Chimera 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 Ransomware.Chimera, and what is the recommended recovery procedure?
Decryption availability for Ransomware.Chimera 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 Chimera from Windows?
Manual removal of Chimera 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.
What are the main symptoms of a Chimera infection?
Symptoms of Chimera 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 Chimera 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
Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/chimera.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.