Peflog

Overview

Executive Summary

Infection Vector and Technical Capabilities

• Comprehensive Keylogging: Peflog utilizes advanced API hooking (often `SetWindowsHookEx`) to capture all keystrokes across all applications. This is designed to capture passwords as they are typed, bypassing browser-based password managers or credential vaults.
• Targeted File Exfiltration: The malware continuously scans the local hard drive and mapped network shares for specific file extensions (e.g., `.doc`, `.xls`, `.pdf`, `.key`, `.pem`). It packages these files into hidden, encrypted archives for exfiltration.
• System Profiling and Exfiltration: It collects extensive system details and periodically takes desktop screenshots to monitor user activity. All stolen data is typically exfiltrated via HTTP POST requests or FTP uploads to an attacker-controlled drop server.

Threat Assessment

Incident Response and Remediation

• Immediate Network Isolation: The highest priority is to physically disconnect the infected machine from the network to halt the active exfiltration of data and prevent the malware from capturing further credentials.
• Global Credential Reset: Because of the pervasive keylogging capabilities, ALL credentials used on that machine—including domain admin passwords, web app logins, and VPN tokens—must be considered compromised and reset immediately.
• Endpoint Eradication: The extent of the data breach and the likelihood of advanced persistence mechanisms necessitate a full forensic review. Re-imaging the machine from a trusted baseline is required to ensure complete eradication.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan.Peflog
• PWS.Peflog
• TrojanSpy.Peflog

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_PEFLOG_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Peflog"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "peflog" ascii wide nocase
        $s2 = "trojan.peflog" ascii wide nocase
        $s3 = "pws.peflog" ascii wide nocase
        $s4 = "trojanspy.peflog" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Peflog (Trojan) Execution & Triage
id: 941732a7-6c68-5929-85b4-a0c1217b076a
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Peflog 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/peflog
- 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.t1056_001
- attack.t1119
- attack.t1048
- attack.t1113
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_PEFLOG_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Peflog 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 = "peflog" 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. Sever network connectivity for the flagged endpoint to terminate persistent command-and-control (C2) communication channels and stop Peflog from retrieving secondary stage payloads.
2. Capture process memory triage to detect and terminate malicious threads injected by Peflog into legitimate system processes such as explorer.exe or svchost.exe.
3. Audit Windows Registry Run keys (HKCU\Software\Microsoft\Windows\CurrentVersion\Run) and Task Scheduler entries to locate and purge Peflog persistence hooks.
4. Deploy updated enterprise EDR detection signatures and conduct an out-of-band endpoint scan to isolate dropped binaries and staged payloads.
5. Rotate all credentials, domain user passwords, and session cookies active on the system during the Peflog execution timeframe.

What to Avoid

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

1. Do not assume the incident is resolved simply because an antivirus tool removed the initial Peflog dropper; always verify that secondary payloads and persistence hooks have been eradicated.
2. Avoid logging in with Domain Admin or privileged credentials on a machine suspected of running Peflog until memory triage is complete.
3. Do not delay host isolation; automated lateral movement and credential dumping can occur within minutes of initial execution.

References & External Analysis

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

Frequently Asked Questions

Related Threats (Category: Trojan)

Explore other documented threats in the same operational category:

• Dragonbot
• Browseban
• Llac
• Plinch
• Staser
• Rz0Auircb0Di
• Staem
• Picsys

Machine-readable

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