Potential Linux Ransomware Note Creation Detectededit
This rule identifies a sequence of a mass file encryption event in conjunction with the creation of a .txt file with a file name containing ransomware keywords executed by the same process in a 1 second timespan. Ransomware is a type of malware that encrypts a victim’s files or systems and demands payment (usually in cryptocurrency) in exchange for the decryption key. One important indicator of a ransomware attack is the mass encryption of the file system, after which a new file extension is added to the file.
Rule type: eql
Rule indices:
- logs-endpoint.events.*
Severity: high
Risk score: 73
Runs every: 5m
Searches indices from: now-9m (Date Math format, see also Additional look-back time)
Maximum alerts per execution: 100
References: None
Tags:
- Domain: Endpoint
- OS: Linux
- Use Case: Threat Detection
- Tactic: Impact
Version: 3
Rule authors:
- Elastic
Rule license: Elastic License v2
Rule queryedit
sequence by host.id, process.entity_id with maxspan=1s
[ file where host.os.type == "linux" and event.type == "change" and
event.action == "rename" and file.extension != "" and
file.path : (
"/home/*", "/etc/*", "/root/*", "/opt/*", "/var/backups/*", "/var/lib/log/*"
) and not
file.extension : (
"xml", "json", "conf", "dat", "gz", "info", "mod", "final",
"php", "pyc", "log", "bak", "bin", "csv", "pdf", "cfg", "*old"
) and not
process.name : (
"dpkg", "yum", "dnf", "rpm", "dockerd"
) ] with runs=100
[ file where host.os.type == "linux" and event.action == "creation" and file.extension == "txt" and
file.name : (
"*crypt*", "*restore*", "*lock*", "*recovery*", "*data*",
"*read*", "*instruction*", "*how_to*", "*ransom*"
) ] | tail 1
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Impact
- ID: TA0040
- Reference URL: https://attack.mitre.org/tactics/TA0040/
-
Technique:
- Name: Data Encrypted for Impact
- ID: T1486
- Reference URL: https://attack.mitre.org/techniques/T1486/