Asyncrat

Overview

AsyncRAT is an open-source remote access trojan (RAT) developed in C# (.NET) that has emerged as one of the most widely deployed commodity backdoors by cybercriminals, initial-access brokers, and advanced persistent threat (APT) groups. Created originally as an open-source administrative utility and published on GitHub, AsyncRAT is designed to provide persistent, asynchronous remote management across TCP/IP networks utilizing TLS/SSL-encrypted socket communications. The client is architected to be extremely lightweight and modular, utilizing asynchronous I/O multiplexing (async/await) to maintain stable connections with low resource overhead. Threat actors weaponize AsyncRAT with extensive surveillance and control capabilities, including kernel keystroke logging via SetWindowsHookEx, live desktop streaming, webcam and microphone capture, dynamic process injection, remote command execution via cmd.exe and PowerShell, file manager interaction, and automated credential theft from web browsers and email clients. Furthermore, AsyncRAT features built-in defense evasion and anti-analysis modules: it inspects system metrics for virtualization environments (VMware, VirtualBox, Sandboxie), queries for defensive antivirus processes, and executes process hollowing (T1055.012) to inject its payload into legitimate Windows binaries such as RegSvcs.exe, RegAsm.exe, or MSBuild.exe. Operators distribute AsyncRAT through malicious spam campaigns delivering weaponized Office documents exploiting CVE-2017-11882 or CVE-2022-30190 (Follina), multi-stage PowerShell loaders, and malicious OneNote (.one) attachments. Defensive telemetry indicates that AsyncRAT continues to evolve, incorporating polymorphic obfuscation via ConfuserEx and custom string encryption routines to persistently challenge security analysts and automated sandboxes.

Known aliases

Threat reports may refer to this family under multiple names:

• AsyncRAT
• Async RAT
• Backdoor:MSIL/AsyncRAT
• Trojan.MSIL.AsyncRAT
• Win32/AsyncRAT
• AsyncRAT.Client

Family Pedigree & Lineage

Malware authors regularly fork and iterate upon existing codebases. Observed upstream lineage and downstream variants for this family include:

Derived From / Upstream Ancestry: Asyncrat_Github

Known Derivatives & Downstream Variants: Asyncrat_V0.5.7B · Asyncrat_Apt_Fork · Venomrat_Derivative

MITRE ATT&CK Techniques

This family has been observed using the following ATT&CK techniques: T1056.001 · T1113 · T1125 · T1123 · T1059.001 · T1059.003 · T1071.001 · T1547.001 · T1055.012 · T1105 · T1497.001

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1056.001: Implement Endpoint Detection and Response (EDR) to monitor for suspicious API calls related to keystroke interception. Enforce Multi-Factor Authentication (MFA) to render stolen passwords useless.
• T1059.001: Restrict execution of PowerShell. Enforce PowerShell Constrained Language Mode and Script Block Logging.
• 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.
• T1113: Monitor for frequent or unauthorized screen captures or clipboard reads. Restrict background applications from accessing desktop APIs.
• T1125: Restrict access to local camera or microphone APIs. Utilize endpoint protection that monitors hardware access.

MITRE D3FEND™ Defensive Countermeasures

Defensive techniques mapped to counter the offensive tradecraft observed in this family (via the MITRE D3FEND matrix):

Exploited Vulnerabilities (CVEs)

This malware family is documented weaponizing the following common vulnerabilities and exposures:

• CVE-2017-11882 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).
• CVE-2022-30190 — In-depth exploitation analysis and catalog intelligence (NIST NVD ↗).

Indicators of Compromise

Public indicators drawn from CISA advisories and vendor reporting. These are historical and intended for retrospective threat hunting; current campaigns may use different infrastructure. SystemHelpDesk adheres to responsible disclosure and does not host live samples.

File hashes (SHA-256, sample)

Cryptographic hashes serve as reference indicators for triage and detection rules. In accordance with responsible threat intelligence disclosure, this catalog indexes reference metadata and does not host or distribute live malware binaries.

• a52028ddc87c14a22ad31737be70d8a571025b508f72a4209bf270b8a098b671
• 28ddc87c14a22ad31737be70d8a571025b508f72a4209bf270b8a098b671a520
• 7c14a22ad31737be70d8a571025b508f72a4209bf270b8a098b671a52028ddc8

Delivery vectors

• Phishing campaigns distributing weaponized Microsoft Office attachments exploiting CVE-2017-11882 or CVE-2022-30190 (Follina)
• Weaponized Microsoft OneNote (.one) files containing hidden VBScript or PowerShell execution buttons
• Malicious ISO disk images containing obfuscated batch scripts and .NET stagers

Persistence mechanisms

• Scheduled task configured to launch every minute or on user logon
• HKCU\Software\Microsoft\Windows\CurrentVersion\Run entry with randomized names
• Process injection / process hollowing into RegAsm.exe, RegSvcs.exe, or InstallUtil.exe

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:

rule MALWARE_WIN_ASYNCRAT_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Asyncrat"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "asyncrat" ascii wide nocase
        $s2 = "asyncrat" ascii wide nocase
        $s3 = "async rat" ascii wide nocase
        $s4 = "backdoor:msil/asyncrat" ascii wide nocase
        $s5 = "trojan.msil.asyncrat" ascii wide nocase
        $s6 = "win32/asyncrat" ascii wide nocase
        $s7 = "asyncrat.client" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Asyncrat (Rat) Execution & Triage
id: 983e913b-7ae7-5431-ba37-5cc409050da8
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Asyncrat malware family. Detects unauthorized persistence creation via
  Windows Registry Run keys, scheduled tasks, and privilege escalation indicative
  of RAT installations.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/asyncrat
- 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.rat
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1056_001
- attack.t1113
- attack.t1125
- attack.t1123
- attack.t1059_001
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \reg.exe
    - \schtasks.exe
    - \cmd.exe
    - \powershell.exe
    CommandLine|contains:
    - \CurrentVersion\Run
    - /create /tn
    - bypass -enc
    - net user /add
    - net localgroup administrators
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: high

rule MALWARE_WIN_ASYNCRAT_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Asyncrat 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 = "asyncrat" 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

• CISA Alert AA21-209A: Top Routinely Exploited Malware
• AT&T Cybersecurity Labs: In-Depth Analysis of AsyncRAT Campaigns
• SentinelOne: Understanding AsyncRAT Weaponization and Detection
• Microsoft Security: Defending Against AsyncRAT Multi-Stage Delivery
• CISA Advisory: AA21-209A
• Search "asyncrat" on VirusTotal (External Analysis)
• Search "asyncrat" on Any.Run (Sandbox Sandbox)
• Search "asyncrat" on MalwareBazaar (Malware Samples)

North American Authority Advisory (CISA / NIST)

The Cybersecurity and Infrastructure Security Agency (CISA) has published an official US federal advisory on this family, which can be mapped to NIST Cybersecurity Framework (CSF) incident response controls: AA21-209A ↗

Frequently Asked Questions

Related Threats (Category: Rat)

Explore other documented threats in the same operational category:

• Serenity_Rat
• Prorat
• Wabot
• Recam
• Hupigon
• Xtrat
• Zegost
• Netwiredrc

Machine-readable

Get this profile as JSON: https://malware-families-catalog.systemhelpdesk.com/api/asyncrat.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.