Malware

Seth-Locker

Seth-Locker is ransomware. The provided content states that it can encrypt files on a targeted system and appends the .seth suffix to encrypted files. It is listed as Enterprise ATT&CK software in the October 2021 ATT&CK v10 release. No additional high-confidence details are provided in the content regarding infection vector, cryptographic implementation, associated threat actors, targeted industries, or other indicators beyond the .seth file extension.

For your environment

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MITRE ATT&CK

Techniques & procedures

3 distinct techniques documented for this family, organized by ATT&CK tactic.

Execution

1 technique

T1059.003Windows Command ShellEvidence4

The content repeatedly describes threat actors and malware using cmd.exe, the Windows command shell, to execute commands, launch payloads, run batch files, and automate actions on compromised hosts.

Command and Control

1 technique

T1105Ingress Tool TransferEvidence2

The content repeatedly describes malware and threat actors that can "download files from C2," "download additional payloads," "upload and download files," "retrieve payloads from the C2 server," and "copy files to remote machines."

Impact

1 technique

T1486Data Encrypted for ImpactEvidence1

ACTIVITY FEED

Recent activity

3 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

3 SOURCESView more in app

mitre attack websiteNews

Oct 21, 2021

Updates - Updates - October 2021 | MITRE ATT&CK®

Enterprise New Software: ... Seth-Locker

mitre attackNews

Jan 23, 2026

Data Encrypted for Impact, Technique T1486 - Enterprise | MITRE ATT&CK®

Ransomware that encrypts files and appends .seth suffix.

mitre attackNews

Mar 18, 2026

Data Encrypted for Impact, Technique T1486 - Enterprise | MITRE ATT&CK®

Ransomware that encrypts files and appends .seth extension.

What this page doesn’t show

The version that knows your environment.

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IOC matching

Match every observed IP, domain, and hash against your live telemetry.

Threat actor attribution

Named campaigns wielding this family, with evidence pinned to each claim.

Exploited vulnerabilities

CVEs this family uses for access and lateral movement.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

MITRE ATT&CK mapping3

Every documented technique, ranked by evidence weight.

Researcher chatter

Reddit, Mastodon, and CTI community discussion around this family.

Seth-Locker