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MITRE ATT&CK® Malware

S1051: KEYPLUG

KEYPLUG is a modular backdoor written in C++, with Windows and Linux variants, that has been used by APT41 since at least June 2021.[1]

EnterpriseS1051MalwareObject v1.1Modified
Glexia's Take · Automated analysis

Security context for executives and security teams

Automation confidenceMedium

S1051: KEYPLUG describes [KEYPLUG](https://attack.mitre.org/software/S1051) is a modular backdoor written in C++, with Windows and Linux variants, that has been used by [APT41](https://attack.mitre.org/groups/G0096) since at least June 2021.(Citation: Mandiant APT41)

Executive priority

S1051: KEYPLUG is an official MITRE ATT&CK software. Glexia treats it as defensive behavior context for prioritizing monitoring, control validation, and response planning without using the object by itself as an attribution claim.

Technical view

Security teams should validate S1051: KEYPLUG by reviewing the official ATT&CK relationships, mapped tactics (the mapped ATT&CK tactic context), supported platforms (Linux, Windows), and available local telemetry before making detection or mitigation decisions.

Likely telemetry

  • Official ATT&CK relationships and object metadata
  • Network, endpoint, and security-tool telemetry

Detection direction

  • Validate whether S1051: KEYPLUG appears in your detection coverage and tabletop scenarios.
  • Use the object to align executive risk language with SOC, incident response, and detection engineering work.
  • Do not treat ATT&CK relationship context as attribution without corroborating evidence.

Mitigation priorities

  • Map the object to existing controls and identify missing telemetry or response ownership.
  • Prioritize mitigations that reduce exposure on the listed platforms and tactics.
  • Review adjacent ATT&CK relationships before changing policy, detections, or reporting language.
Additional notes and limits

Baseline Glexia take generated from the official MITRE ATT&CK STIX object, source hash, tactics, platforms, and detection fields. It is safe to replace with a richer model-generated take for the same source hash later.

This baseline take is source-grounded and schema-validated, but it does not include environment-specific telemetry, incident evidence, or threat-intelligence corroboration.

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Official MITRE ATT&CK definition

KEYPLUG

KEYPLUG is a modular backdoor written in C++, with Windows and Linux variants, that has been used by APT41 since at least June 2021.[1]

View the same entry on attack.mitre.org (MITRE-hosted reference; in-page links above use the Glexia ATT&CK library.)

Glexia analysis

How security teams should use this page

Treat this object as behavior context, not an attribution claim. Validate the related groups, software, data sources, and mitigations against official ATT&CK relationships and your own telemetry before making control-coverage decisions.

ATT&CK relationship table

Techniques used

This mirrors the MITRE pattern of making group, software, campaign, and technique relationships scannable. Relationship notes come from mirrored ATT&CK relationship text when available.

8 rows
DomainIDNameRelationship / procedure
EnterpriseT1071.001Web ProtocolsSub-technique

KEYPLUG has the ability to communicate over HTTP and WebSocket Protocol (WSS) for C2.[1]

EnterpriseT1124System Time Discovery

KEYPLUG can obtain the current tick count of an infected computer.[1]

EnterpriseT1102.001Dead Drop ResolverSub-technique

The KEYPLUG Windows variant has retrieved C2 addresses from encoded data in posts on tech community forums.[1]

EnterpriseT1027.013Encrypted/Encoded FileSub-technique

KEYPLUG can use a hardcoded one-byte XOR encoded configuration file.[1]

EnterpriseT1140Deobfuscate/Decode Files or Information

KEYPLUG can decode its configuration file to determine C2 protocols.[1]

EnterpriseT1573.002Asymmetric CryptographySub-technique

KEYPLUG can use TLS-encrypted WebSocket Protocol (WSS) for C2.[1]

EnterpriseT1090Proxy

KEYPLUG has used Cloudflare CDN associated infrastructure to redirect C2 communications to malicious domains.[1]

EnterpriseT1095Non-Application Layer Protocol

KEYPLUG can use TCP and KCP (KERN Communications Protocol) over UDP for C2 communication.[1]

Associated objects

Groups, software, and campaigns

GroupEnterprise

G0096: APT41

APT41 is a threat group that researchers have assessed as Chinese state-sponsored espionage group that also conducts financially-motivated operations. Active since at least 2012, APT41 has been observed targeting various industries, including but not limited to healthcare, telecom, technology, finance, education, retail and video game industries in 14 countries.[1] Notable behaviors include using a wide range of malware and tools to complete mission objectives. APT41 overlaps at least partially with public reporting on groups including BARIUM and Winnti Group.[2][3]

CampaignEnterprise

C0017: C0017

C0017 was an APT41 campaign conducted between May 2021 and February 2022 that successfully compromised at least six U.S. state government networks through the exploitation of vulnerable Internet facing web applications. During C0017, APT41 was quick to adapt and use publicly-disclosed as well as zero-day vulnerabilities for initial access, and in at least two cases re-compromised victims following remediation efforts. The goals of C0017 are unknown, however APT41 was observed exfiltrating Personal Identifiable Information (PII).[1]

Relationship explorer

All related ATT&CK context

Change history

Object version and sync metadata

The fields below describe the current mirrored snapshot. When Glexia retains multiple ATT&CK source imports, you can open the table to compare the same object across releases (hashes and MITRE timestamps). For MITRE’s own release notes and roadmap, see ATT&CK resources — Updates.

ATT&CK release
19.2
Object version
1.1
Created
Modified
Raw hash
cdc6c85236bd3f98...
Imported snapshots across ATT&CK releases(2)
ReleaseBundle importedObject versionModifiedStatusRaw hash
19.21.1Current bundlecdc6c85236bd…
19.11.1Older bundlecdc6c85236bd…
Raw source

Mirrored ATT&CK source object

The raw object is retained through the mirrored ATT&CK source bundle and object hash. The raw endpoint returns the exact object from the mirrored bundle when available.

Source references

External references and citations

MITRE external references are preserved separately from Glexia analysis so citations remain traceable to their original source records.

  1. [1]
    Mandiant APT41

    Rufus Brown, Van Ta, Douglas Bienstock, Geoff Ackerman, John Wolfram. (2022, March 8). Does This Look Infected? A Summary of APT41 Targeting U.S. State Governments. Retrieved July 8, 2022.

    Open source URL
  2. [2]
    KEYPLUG.LINUX

    (Citation: Mandiant APT41)

  3. [3]
    mitre-attackS1051
    Open source URL
Source and licensing

Source: MITRE ATT&CK®. © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. MITRE ATT&CK and ATT&CK are registered trademarks of The MITRE Corporation. Glexia is not affiliated with or endorsed by MITRE.