Keyer

Overview

Executive Summary

Infection Vector and Technical Capabilities

• Keystroke Interception: The malware utilizes Windows API hooking (specifically utilizing `SetWindowsHookEx`) to intercept hardware interrupts from the keyboard. This allows it to record every single keystroke before it reaches the intended application.
• Contextual Logging: Advanced variants of Keyer do not just record raw keystrokes; they record the title of the active window where the keystrokes were entered. This allows attackers to easily parse the logs to find the specific keystrokes entered into "Bank of America Login" or "VPN Authentication."
• Exfiltration: The recorded logs are typically saved locally to a hidden, encrypted file. Periodically, the keylogger will silently transmit this file to an attacker-controlled server via SMTP (email), FTP, or HTTP POST requests.

Threat Assessment

Incident Response and Remediation

• Immediate Network Isolation: Isolate the machine to immediately halt the outbound transmission of the recorded keylogs.
• Complete Credential Reset: Assume that every password ever typed on the infected machine (including network domain credentials, personal banking, and social media) has been compromised. The user must initiate a comprehensive password reset from a known-secure, separate device.
• Endpoint Sweeps: Utilize robust EDR or anti-malware tools to locate and terminate the keylogger process. Pay close attention to hidden files in `%AppData%` and anomalous entries in the Registry `Run` keys used for persistence.

Known aliases

Threat reports may refer to this family under multiple names:

• Trojan.Keylogger.Keyer
• Spyware.Keyer
• Win32/Keyer

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.

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_KEYER_T1_ARTIFACT {
    meta:
        description = "Tier 1 Primitive Artifact: Raw string matches for Keyer"
        tier = "T1 - Primitive Artifact"
        confidence = "Low-Medium (Fast Triage)"
        author = "SystemHelpdesk Threat Research Desk"
        date = "2026-10-14"
    strings:
        $s1 = "keyer" ascii wide nocase
        $s2 = "trojan.keylogger.keyer" ascii wide nocase
        $s3 = "spyware.keyer" ascii wide nocase
        $s4 = "win32/keyer" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

title: SystemHelpDesk Detection - Keyer (Advanced Threat) Execution & Triage
id: 18da94bf-e5aa-5008-a1a4-81b0b375d68e
status: production
description: Detects execution, defense evasion, and persistence behaviors associated
  with the Keyer malware family. Detects proxy execution, reflective DLL loading,
  and remote command injection associated with modular enterprise backdoors.
references:
- https://malware-families-catalog.systemhelpdesk.com/families/keyer
- 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.advanced-threat
- author.ricky-jordan
- source.systemhelpdesk-mfc
- attack.t1056_001
- attack.t1114
- attack.t1547_001
logsource:
  category: process_creation
  product: windows
detection:
  selection_process:
    Image|endswith:
    - \powershell.exe
    - \cmd.exe
    - \rundll32.exe
    - \regsvr32.exe
    CommandLine|contains:
    - DownloadString
    - IEX(
    - '/s /n /u /i:'
    - sc create
    - start-process
  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_KEYER_T3_ATTRIBUTION {
    meta:
        description = "Tier 3 Attribution Fingerprint: Heuristic detection for Keyer 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 = "keyer" 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. Enforce forensic network isolation on all suspected endpoints while maintaining an out-of-band telemetry conduit to capture live Keyer adversary activity.
2. Perform full memory dumps across identified staging nodes to extract memory-only implants, kernel rootkit hooks, and decrypted Keyer C2 infrastructure IP/domain lists.
3. Review Active Directory domain controller authentication logs for anomalous Kerberos ticket requests (Pass-the-Ticket, Golden Ticket) and unauthorized DCSync operations associated with Keyer.
4. Block all confirmed C2 domains, dynamic DNS endpoints, and proxy IP addresses across perimeter firewalls, proxies, and DNS security gateways.
5. Conduct an enterprise-wide sweep across surrounding subnets for secondary webshells, WMI event subscriptions, or remote execution tooling left behind by Keyer operators.

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

Frequently Asked Questions

Related Threats (Category: Advanced Threat)

Explore other documented threats in the same operational category:

• Tencent
• Plicker
• Menti
• Diskscanfa
• Mapsgory
• Scramupx
• Kuping
• Refogkeylogging

Machine-readable

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