Perflogger

Overview

Spyware:Win32/Perflogger is a covert surveillance tool and keylogger designed to secretly record user activity, capture keystrokes, monitor clipboard contents, and exfiltrate sensitive data (such as passwords, financial details, and personal communications) to a remote attacker.

Understanding Perflogger
To the victim, Perflogger operates entirely invisibly, with no outward signs of infection aside from a potential, minor decrease in system performance. For security analysts, a keylogger represents an immediate and total compromise of user credentials and sensitive data. Perflogger is often deployed as a secondary payload by a dropper trojan, or installed manually by an attacker who has already gained initial access.

Execution and Data Capture Mechanics
Perflogger typically establishes persistence via Registry Run keys (`T1547.001`) to ensure it starts immediately upon user login. To capture data, it relies heavily on native Windows API hooking. It utilizes `SetWindowsHookEx` to intercept keyboard input globally across all applications (`T1056.001`). It may also periodically capture screenshots (`T1113`) and monitor the system clipboard for copied passwords (`T1115`). The stolen data is temporarily stored locally in hidden, encrypted log files (`T1005`) before being bundled and exfiltrated to a C2 server via FTP, SMTP (email), or HTTP POST requests (`T1041`).

Indicators of Compromise & Impact
The primary impact is identity theft, credential compromise, and data breach. Incident responders should monitor EDR for suspicious processes injecting DLLs to hook input APIs, or processes frequently reading the clipboard. A strong IoC is an unknown executable in `%AppData%` generating small, steadily growing, heavily obfuscated log files and occasionally sending them outbound over FTP or SMTP.

MITRE ATT&CK Techniques

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

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.
• T1113: Monitor for frequent or unauthorized screen captures or clipboard reads. Restrict background applications from accessing desktop APIs.

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_PERFLOGGER_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Perflogger"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "perflogger" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Perflogger (Trojan) Execution & Triage
id: 9a509bf5-7537-5302-8917-75d00cc57804
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Perflogger malware family. Detects suspicious execution from temporary
  user directories with hidden window flags and background transfer utilities.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/perflogger
- https://malware-families-catalog.systemhelpdesk.com/defensive/downloader-dropper-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.trojan
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1115
- attack.t1056_001
- attack.t1113
- attack.t1547_001
- attack.t1041
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \cmd.exe
    - \powershell.exe
    - \cscript.exe
    - \wscript.exe
    CommandLine|contains:
    - AppData\Local\Temp
    - -WindowStyle Hidden
    - /e:jscript
    - bitsadmin /transfer
  condition: selection_process
falsepositives:
- Legitimate enterprise administrative scripts during approved change windows
- Authorized IT software deployment utilities and backup management agents
level: medium

rule MALWARE_WIN_PERFLOGGER_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Perflogger 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 = "perflogger" 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. Assume all passwords typed on the infected machine, as well as all active session cookies, have been compromised. Enforce immediate resets.
2. Isolate the endpoint from the network to halt the active exfiltration of the recorded keylog files.
3. Use EDR to track down the hidden executable responsible for the hooking, and locate the local staging directory where the keylogs are stored.
4. Terminate the keylogger process and remove its persistence mechanisms from the Registry.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. Do not assume Multi-Factor Authentication (MFA) will fully protect the user; keyloggers often capture the MFA tokens as they are typed, and some capture session cookies.
2. Avoid delaying the password reset process; the data is usually exfiltrated rapidly.

References & External Analysis

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

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Sixxpack
• Ircbrute
• Webdevaz
• Genericrxas
• Skorik
• Gametool
• Btcon
• Ymkfawdgfnmi

Machine-readable

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