Redcap
Table of Contents
Overview
Redcap (cataloged across security vendors and threat intelligence databases under signatures including Backdoor:Win32/Redcap, Trojan:Win32/RedCap, and Backdoor.Redcap) is a persistent Windows remote access trojan (RAT) and backdoor active since 2017. Disseminated primarily through malicious email attachments, compromised website downloads, and cracked software packages, Redcap operates covertly to provide threat actors with interactive remote access. Upon execution, Redcap establishes persistence via Windows Registry Run keys and scheduled tasks, conducts system hardware and network reconnaissance, and initiates an encrypted outbound connection to attacker C2 servers. Redcap enables remote operators to execute arbitrary command-line instructions, upload and download files, and drop secondary malware payloads.
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: Backdoor:Win32/Redcap.A · Trojan:Win32/Redcap!Mclg
MITRE ATT&CK Techniques
This family has been observed using the following ATT&CK techniques: T1059.003 · T1547.001 · T1105 · T1071.001 · T1082
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.
- T1071.001: Implement web filtering and SSL/TLS inspection to detect malicious command and control (C2) traffic hiding in HTTP/HTTPS.
- T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.
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-PBA | Process Spawn Analysis | Detect | T1059.003 | Inspect command-line arguments and anomalous parent-child relationships spawning from cmd.exe. |
D3-WAF | Web Content Filtering & Inspection | Filter | T1071.001 | Block newly registered domains (NRDs) and inspect HTTP Host and URI headers for known C2 profiles. |
D3-SDA | System Discovery Analysis | Detect | T1082 | Alert on rapid enumerations of systeminfo, hostname, and registry hardware trees in short intervals. |
D3-NTI | Network Traffic Inspection | Detect | T1105 | Inspect deep packet payloads for anomalous staging binaries and unauthorized egress protocols. |
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_REDCAP_T1_ARTIFACT {
meta:
description = "Tier 1 Primitive Artifact: Raw string matches for Redcap"
tier = "T1 - Primitive Artifact"
confidence = "Low-Medium (Fast Triage)"
author = "SystemHelpdesk Threat Research Desk"
date = "2026-10-14"
strings:
$s1 = "redcap" ascii wide nocase
$s2 = "backdoor:win32/redcap" ascii wide nocase
$s3 = "trojan:win32/redcap" ascii wide nocase
$s4 = "backdoor.redcap" ascii wide nocase
$s5 = "win32/redcap" ascii wide nocase
$s6 = "backdoor:win32/redcap.a" 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 - Redcap (Backdoor) Execution & Triage
id: 6701f265-f067-5381-9b2e-c3a042006e84
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
with the Redcap malware family. Detects proxy execution, reflective DLL loading,
and remote command injection associated with modular enterprise backdoors.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/redcap
- https://malware-families-catalog.systemhelpdesk.com/defensive/backdoor-rat-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.backdoor
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1059_003
- attack.t1547_001
- attack.t1105
- attack.t1071_001
- attack.t1082
logsource:
category: process_creation
product: windows
detection:
selection_process:
Image|endswith:
- \powershell.exe
- \cmd.exe
- \rundll32.exe
- \regsvr32.exe
CommandLine|contains:
- DownloadString
- IEX(
- '/s /n /u /i:'
- sc create
- start-process
condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: highTier 3 Attribution Fingerprint Rule (High Fidelity)
Deep signature matching distinctive operational fingerprints and payload characteristics.
rule MALWARE_WIN_REDCAP_T3_ATTRIBUTION {
meta:
description = "Tier 3 Attribution Fingerprint: Heuristic detection for Redcap 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 = "redcap" 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 - Backdoor:Win32/Redcap
- Search "redcap" on VirusTotal (External Analysis)
- Search "redcap" on Any.Run (Sandbox Sandbox)
- Search "redcap" on MalwareBazaar (Malware Samples)
Frequently Asked Questions
What is Backdoor:Win32/Redcap?
Redcap is a persistent Windows remote access trojan and backdoor that grants attackers remote command execution.
How does Redcap infect target endpoints?
Through malicious email attachments, cracked software packages, and drive-by downloads from compromised websites.
What remote capabilities are provided by Redcap?
It allows operators to run command prompt commands, upload/download files, capture system info, and stage secondary malware.
How does Redcap maintain persistence on the host?
It modifies Windows Registry Run keys and creates scheduled tasks to restart automatically at system boot.
How can incident responders remove Redcap?
Perform a Microsoft Defender Offline scan, terminate rogue background processes, and reset compromised account passwords.
How do I remove the Redcap Backdoor from Windows?
Manual removal of Redcap 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 Redcap a virus or a Backdoor?
Redcap is classified as a Backdoor. Unlike traditional viruses that infect files, modern malware like Redcap typically operates as a standalone payload designed to compromise systems, steal data, or deploy secondary stage implants.
What are the main symptoms of a Redcap infection?
Symptoms of Redcap 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 Backdoors
Want to prevent Redcap and similar threats from compromising your organization? Read our comprehensive defensive guide: Backdoor & RAT Protection for Businesses.
📣 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/redcap.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.
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