Resod
Table of Contents
Overview
Resod (tracked across threat intelligence and antivirus telemetry under signatures including Ransom:Win32/Resod, Trojan-Ransom.Win32.Resod, and Win32/Resod) is a high-impact Windows crypto-ransomware family designed for corporate network extortion. Delivered primarily through brute-forced Remote Desktop Protocol (RDP) sessions, compromised VPN credentials, and malicious software downloaders, Resod targets corporate servers and endpoints to encrypt critical business records. Upon execution, Resod executes administrative shell commands to terminate database, hypervisor, and backup services (such as MSSQL, MySQL, Veeam, and vCenter services) using 'net stop' and 'taskkill', ensuring that databases and virtual disk files can be opened with write access. It systematically destroys system restore points and volume shadow copies using 'vssadmin delete shadows /all /quiet', 'wmic shadowcopy delete', and 'wbadmin delete catalog -quiet'. Resod encrypts targeted user documents, virtual machines, and databases using AES-256 in CBC mode, appending the '.resod' extension to all locked files. It embeds the session key encrypted under an embedded 2048-bit RSA master public key within each file header, and drops ransom notes ('HOW_TO_RESTORE_FILES.txt') directing victims to Tor negotiation portals.
Known aliases
Threat reports may refer to this family under multiple names:
Family Pedigree & Lineage
Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:
Known Derivatives & Downstream Variants: Ransom:Win32/Resod.A · Ransom:Win32/Resod.B
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1486 · T1490 · T1489 · T1083 · T1027
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-BDA | Binary De-obfuscation & Unpacking | Analyze | T1027 | Utilize memory dump scanners and entropy inspection to unpack encrypted stagers during process creation. |
D3-FDA | File Directory Access Auditing | Detect | T1083 | Audit and alert on high-frequency recursive directory queries executed by non-system and unclassified binaries. |
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-SPP | Service Protection Policies | Harden | T1489 | Configure strict DACLs on Windows Service Control Manager to prevent unauthorized termination of antivirus and backup services. |
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_RESOD_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Resod"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "resod" ascii wide nocase
$s2 = "ransom:win32/resod" ascii wide nocase
$s3 = "trojan-ransom.win32.resod" ascii wide nocase
$s4 = "win32/resod" ascii wide nocase
$s5 = "ransom.resod" ascii wide nocase
$s6 = "resod ransomware" 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 - Resod (Ransomware) Execution & Triage
id: 35715185-7bc5-531c-9de7-05728969b479
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Resod 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/resod
- 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.t1490
- attack.t1489
- attack.t1083
- attack.t1027
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_RESOD_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Resod 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 = "resod" 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
}References & External Analysis
- Microsoft Defender Threat Encyclopedia - Ransom:Win32/Resod
- Trend Micro Threat Encyclopedia - Ransom.Win32.Resod
- Search "resod" on VirusTotal (External Analysis)
- Search "resod" on Any.Run (Sandbox Sandbox)
- Search "resod" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Ransom:Win32/Resod?
Resod is a corporate-targeting crypto-ransomware that terminates database services and encrypts critical files using AES-256 and RSA-2048.
How does Resod prevent victims from restoring files from shadow copies?
It executes vssadmin and wmic commands to delete all volume shadow copies and system backup catalogs.
How does Resod infect corporate networks?
Attackers deploy Resod through brute-forced RDP connections, compromised VPN credentials, or secondary trojan loaders.
Can files encrypted with the .resod extension be decrypted for free?
No public decryption tool exists because Resod uses standard AES-256 with keys protected by an asymmetric RSA-2048 public key.
What incident response steps should be taken during a Resod incident?
Isolate all affected network subnets immediately, preserve forensic memory images, block external C2/Tor traffic, and restore data from offline backups.
How do I remove the Resod Ransomware from Windows?
Manual removal of Resod 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 Resod a virus or a Ransomware?
Resod is classified as a Ransomware. Unlike traditional viruses that infect files, modern malware like Resod typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Resod infection?
Symptoms of Resod 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 Resod 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/resod.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.