Psexec

Overview

Executive Summary

Technical Capabilities and Malicious Abuse

• Lateral Movement: Once an attacker dumps credentials (e.g., using Mimikatz) and obtains a Domain Admin hash, they use PsExec (or heavily modified clones like Impacket's `psexec.py`) to "pass the hash." This allows them to instantly gain interactive command-line access to any server or workstation in the domain without cracking the actual password.
• Ransomware Deployment: Ransomware operators (such as Ryuk or Conti) frequently write scripts that loop through lists of all active IP addresses on the corporate network, utilizing PsExec to push the ransomware executable to every machine simultaneously, ensuring maximum destruction before defenders can react.
• Evasion: Because PsExec is a Microsoft-signed administrative tool, its execution is often ignored by legacy antivirus solutions, making it an ideal "fileless" execution vector.

Threat Assessment

Incident Response and Remediation

• Behavioral Monitoring (EDR): Security teams must tune their EDR solutions to aggressively monitor the usage of PsExec. Alerts should trigger if PsExec is launched by non-administrative accounts, or if it is used to execute known malicious binaries, PowerShell scripts, or batch files.
• Network Segmentation (SMB): Limit lateral movement by heavily restricting SMB traffic (TCP Port 445) between workstations. Only allow designated administrative jump boxes to initiate SMB connections to endpoints.
• Credential Tiering: Implement the Microsoft Tiered Admin Model to prevent Domain Admin credentials from being cached on standard workstations, denying attackers the high-privileged accounts required to abuse PsExec across the enterprise.

Known aliases

Threat reports may refer to this family under multiple names:

• HackTool.PsExec
• Sysinternals.PsExec
• LateralMovement.Tool

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to our technical analysis hubs and the official MITRE ATT&CK framework:

MITRE D3FEND™ Defensive Countermeasures

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

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_PSEXEC_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Psexec"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "psexec" ascii wide nocase
        $s2 = "hacktool.psexec" ascii wide nocase
        $s3 = "sysinternals.psexec" ascii wide nocase
        $s4 = "lateralmovement.tool" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Psexec (Ransomware) Execution & Triage
id: f00365aa-a81f-5b5d-9a0e-8d522496ac99
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Psexec 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/psexec
- 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.t1569_002
- attack.t1021_002
- attack.t1570
- attack.t1543_003
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: critical

rule MALWARE_WIN_PSEXEC_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Psexec 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 = "psexec" 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.

1. Immediately isolate affected host(s) from the internal network (disconnect physical Ethernet and disable Wi-Fi/Bluetooth) to prevent Psexec from spreading laterally or encrypting network-attached storage (NAS) and shared SMB volumes.
2. Preserve volatile system memory (RAM capture) on a representative endpoint before attempting a reboot or power-down, as Psexec symmetric encryption keys or uncompiled payload components may still reside in memory.
3. 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 Psexec to inhibit recovery.
4. 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.
5. Restore critical assets and databases exclusively from verified, air-gapped, or immutable offline backups once the Psexec 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.

1. Do not restart or power cycle infected systems prematurely; doing so destroys volatile RAM encryption keys and may trigger bootloader locking logic embedded in Psexec.
2. Avoid negotiating or paying the extortion demand without prior forensic evaluation and consultation with incident response specialists, as payment does not guarantee data recovery.
3. Do not connect clean backup drives or external storage to the affected network until Psexec eradication is completely verified.

References & External Analysis

• Search "psexec" on VirusTotal (External Analysis)
• Search "psexec" on Any.Run (Sandbox Sandbox)
• Search "psexec" on MalwareBazaar (Malware Samples)

Frequently Asked Questions

Related Threats (Category: Ransomware)

Explore other documented threats in the same operational category:

• Hydracrypt
• Microjoin
• Zxrloader
• Joiner
• Pshell
• Amgfvjgvdoaan
• Wyhymyz
• Homles

Machine-readable

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