Potential Linux Ransomware Note Creation Detected
editPotential Linux Ransomware Note Creation Detected
editRansomware 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. Generally, a ransomware note with contact details is dropped onto the file system which can be used by the victim to contact the attacker. 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.
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:
- Elastic
- Host
- Linux
- Threat Detection
- Impact
Version: 1
Rule authors:
- Elastic
Rule license: Elastic License v2
Rule query
editsequence 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 != "" ] with runs=50 [ 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/