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Potential Process Injection via LD_PRELOAD Environment Variable

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Potential Process Injection via LD_PRELOAD Environment Variable

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This rule detects the execution of a process where the LD_PRELOAD environment variable is set. LD_PRELOAD can be used to inject a shared library into a binary at or prior to execution. A threat actor may do this in order to load a malicious shared library for the purposes of persistence, privilege escalation, and defense evasion. This activity is not common and will potentially indicate malicious or suspicious behavior.

Rule type: eql

Rule indices:

logs-endpoint.events.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

https://www.getambassador.io/resources/code-injection-on-linux-and-macos

Tags:

Domain: Endpoint
OS: Linux
Use Case: Threat Detection
Tactic: Defense Evasion
Tactic: Persistence
Tactic: Privilege Escalation

Version: 1

Rule authors:

Elastic

Rule license: Elastic License v2

Investigation guide

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## Setup
By default, the `Elastic Defend` integration does not collect environment variable logging. In order to capture this behavior, this rule requires a specific configuration option set within the advanced settings of the `Elastic Defend` integration.
```
Kibana -->
Fleet -->
Agent policies -->
Agent policy for which the option should be enabled -->
Name of the Elastic Defend integration -->
Show advanced settings -->
linux.advanced.capture_env_vars
```
`linux.advanced.capture_env_vars` should be set to `LD_PRELOAD,LD_LIBRARY_PATH`.
After saving the integration change, the Elastic Agents running this policy will be updated and the rule will function properly.

Rule query

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process where host.os.type == "linux" and
 event.action == "exec" and
 process.env_vars : ("LD_PRELOAD=?*", "LD_LIBRARY_PATH=?*")

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Hijack Execution Flow
- ID: T1574
- Reference URL: https://attack.mitre.org/techniques/T1574/
Sub-technique:
- Name: Dynamic Linker Hijacking
- ID: T1574.006
- Reference URL: https://attack.mitre.org/techniques/T1574/006/
Tactic:
- Name: Persistence
- ID: TA0003
- Reference URL: https://attack.mitre.org/tactics/TA0003/
Technique:
- Name: Hijack Execution Flow
- ID: T1574
- Reference URL: https://attack.mitre.org/techniques/T1574/
Sub-technique:
- Name: Dynamic Linker Hijacking
- ID: T1574.006
- Reference URL: https://attack.mitre.org/techniques/T1574/006/
Tactic:
- Name: Privilege Escalation
- ID: TA0004
- Reference URL: https://attack.mitre.org/tactics/TA0004/
Technique:
- Name: Hijack Execution Flow
- ID: T1574
- Reference URL: https://attack.mitre.org/techniques/T1574/
Sub-technique:
- Name: Dynamic Linker Hijacking
- ID: T1574.006
- Reference URL: https://attack.mitre.org/techniques/T1574/006/

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