Suspicious Content Extracted or Decompressed via Funzip

Last updated 9 months ago on 2025-03-20

Created 3 years ago on 2023-06-26

About

Identifies when suspicious content is extracted from a file and subsequently decompressed using the funzip utility. Malware may execute the tail utility using the "-c" option to read a sequence of bytes from the end of a file. The output from tail can be piped to funzip in order to decompress malicious code before it is executed. This behavior is consistent with malware families such as Bundlore.

Tags

Domain: EndpointOS: LinuxUse Case: Threat DetectionTactic: ExecutionData Source: Elastic EndgameData Source: Elastic DefendData Source: SentinelOneLanguage: eql

Severity

medium

Risk Score

MITRE ATT&CK™

Execution (TA0002)(external, opens in a new tab or window)

↳ Command and Scripting Interpreter (T1059)(external, opens in a new tab or window)

Defense Evasion (TA0005)(external, opens in a new tab or window)

↳ Obfuscated Files or Information (T1027)(external, opens in a new tab or window)

↳ Deobfuscate/Decode Files or Information (T1140)(external, opens in a new tab or window)

License

Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type

Event Correlation Rule

Integration Pack

Prebuilt Security Detection Rules

Index Patterns

endgame-*logs-endpoint.events.process*logs-sentinel_one_cloud_funnel.*

Related Integrations

endpoint(external, opens in a new tab or window)

sentinel_one_cloud_funnel(external, opens in a new tab or window)

Query

✄𐘗text code block:
✄𐘗process where host.os.type == "linux" and event.action in ("exec", "exec_event", "start") and
((process.args == "tail" and process.args == "-c" and process.args == "funzip")) and
not process.args : "/var/log/messages" and
not process.parent.executable : ("/usr/bin/dracut", "/sbin/dracut", "/usr/bin/xargs") and
not (process.parent.name in ("sh", "sudo") and process.parent.command_line : "*nessus_su*")

Install detection rules in Elastic Security

Detect Suspicious Content Extracted or Decompressed via Funzip in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).