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 the 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.

Generated Detections (Boilerplate)

These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.

YARA Rule

rule MALWARE_WIN_PERFLOGGER {
    meta:
        description = "Detects Perflogger (trojan)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "perflogger" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Perflogger Activity
id: 62c1b0d45f0d9c67702aa2b7afcfd40d
status: experimental
description: Detects generic indicators of the perflogger malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*perflogger*"
    condition: selection
level: medium

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)

Frequently Asked Questions

Related Families (Category: trojan)

Explore other malware families in the same category:

• Keylogr
• Hvnc
• Goobzo
• Look2Me
• Lockpos

Machine-readable

Get this profile as JSON: https://jordanricky1604-ship-it.github.io/malware-families-catalog/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.