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Recognizing Credential Dumping Attacks Against Linux Servers Through Process and Sensitive-File Monitoring

Description

Linux servers contain authentication-related information that is protected by operating-system permissions and security controls. Files such as `/etc/shadow` contain password-hash information and are restricted to privileged users.

An attacker who gains access to a Linux server may attempt to obtain authentication-related information from protected files or processes. This activity is commonly associated with credential dumping, where an attacker attempts to collect password hashes or other authentication material for further unauthorized access.

If credential-access activity is not monitored, an attacker may be able to obtain sensitive authentication information without generating an immediately visible security event.

In this use case, a real Ubuntu Linux server is deployed inside an isolated VirtualBox laboratory. Kali Linux is used as the authorized security-testing system.

A controlled Linux credential-dumping scenario is reproduced using a harmless laboratory test file that represents protected authentication material. No real passwords or production credentials are exposed.

auditd is used to monitor access to sensitive authentication files and process activity. Wazuh acts as the centralized SOC detection and alert-management platform.

OpenSearch is used for centralized investigation, event correlation, and incident-timeline reconstruction.

osquery is used to provide endpoint visibility into users, processes, and file-related system information.

The suspicious activity is detected by correlating sensitive-file access, process execution, user identity, and abnormal credential-access behavior.

When the configured detection condition is satisfied, Wazuh generates a security alert and the predefined response mechanism restricts the controlled laboratory account or source.

The complete SOC workflow is: Linux Server → Credential-Access Attempt → Sensitive Authentication-File Monitoring → Process Monitoring → Suspicious Activity Detection → Wazuh Alert → OpenSearch Investigation → Source Attribution → Automated Response → Containment → Validation

Existing Security Problem

Application: Linux Authentication Environment

Ubuntu Linux maintains authentication information that is protected by operating-system permissions.

The `/etc/shadow` file contains password-hash information and is normally restricted because unauthorized access to authentication material can create significant security risk.

Existing Problem:

If an attacker gains access to a Linux account, they may attempt to access protected authentication files or collect authentication-related information.

The security problem is therefore:

Compromised Linux Account → Credential-Access Attempt → Protected Authentication File → Unauthorized File Access → Credential Information Obtained → Offline Credential Attack Risk → Potential Account Compromise

Attack

Specific Attack: Linux Credential Dumping

The controlled attack scenario demonstrates how a low-privileged laboratory account may attempt to access protected authentication-related information.

Attack Behavior:
Controlled Low-Privileged Account
→
Credential-Access Attempt
→
Protected Authentication Test File
→
Sensitive-File Access
→
auditd Monitoring
→
Wazuh Detection
→
SOC Security Alert
→
OpenSearch Investigation
→
Automated Response
→
Account Containment

Security Concept

Credential-Access Detection Through Endpoint Monitoring:

The primary security concept is Endpoint Detection and Response for Credential Access.

The SOC monitors sensitive authentication-file access and associated process activity to identify suspicious credential-dumping behavior. The objective is to determine whether a user without a legitimate administrative requirement is attempting to access authentication-related information.

The secure processing flow is:

Sensitive Authentication File
→
File-Access Monitoring
→
Process Monitoring
→
User Attribution
→
Credential-Access Analysis
→
Suspicious Behavior Detection
→
Security Alert
→
Investigation
→
Automated Response
→
Containment
→
Validation

Defensive Mechanism

Sensitive Authentication-File Monitoring

auditd monitors access to protected authentication-related files.

Purpose

Detect unauthorized attempts to access credential information.

Process Execution Monitoring

Process execution associated with credential-access activity is monitored.

Purpose

Identify the process responsible for the suspicious activity.

User Attribution

The user responsible for the file-access operation is identified.

Purpose

Determine which account initiated the credential-access attempt.

Permission Context Analysis

The permission context of the accessing process is reviewed.

Purpose

Determine whether the access is consistent with the user's legitimate privileges.

Credential-Access Detection

Sensitive-file access and process events are correlated.

Purpose

Identify behavior consistent with credential dumping.

Endpoint Visibility

osquery provides endpoint information about users, processes, and system state.

Purpose

Provide additional context during SOC investigation.

Security Alerting

Wazuh generates a security alert when the configured credential-dumping condition is satisfied.

Purpose

Provide centralized SOC visibility.

Centralized Investigation

OpenSearch is used to investigate the generated security events.

Purpose

Correlate file access, process activity, user identity, and timestamps.

Automated Account Protection

Wazuh Active Response can temporarily restrict the controlled test account.

Purpose

Prevent continued unauthorized credential-access attempts.

Post-Containment Validation

The controlled credential-access activity is repeated after containment.

Purpose

Confirm that the response prevents continued access to protected authentication information.

Security Tools

Primary Endpoint Audit Tool: auditd

auditd is used to collect Linux security-audit events.

Purpose
  • Monitor sensitive-file access.
  • Monitor process execution.
  • Record user identity.
  • Record file-access activity.
  • Provide audit evidence.

Primary SOC Monitoring Platform: Wazuh

Wazuh is used as the centralized SOC detection and response platform.

Purpose
  • Collect audit events.
  • Process credential-access events.
  • Generate security alerts.
  • Correlate security activity.
  • Support Active Response.
  • Provide centralized SOC visibility.

Endpoint Visibility Tool: osquery

osquery provides endpoint visibility through SQL-based system queries.

Purpose
  • Identify users.
  • Review running processes.
  • Review system state.
  • Support endpoint investigation.
  • Provide additional context for credential-access events.

Security Investigation Platform: OpenSearch

OpenSearch is used for centralized SOC investigation.

Purpose
  • Search security events.
  • Investigate credential-access activity.
  • Correlate audit events.
  • Review timestamps.
  • Establish incident timelines.

Controlled Credential-Access Testing Tool: Python

Python is used to generate harmless laboratory credential material and controlled file-access activity.

Purpose
  • Create synthetic credential data.
  • Create the protected laboratory test file.
  • Generate controlled access events.
  • Validate detection behavior.
  • Support post-remediation testing.

Target Platform: Ubuntu Linux

Ubuntu provides the controlled Linux server environment.

Purpose
  • Host the authentication test environment.
  • Generate process and file-access telemetry.
  • Run auditd and osquery.
  • Apply containment and remediation actions.

Security Testing Platform: Kali Linux

Kali Linux provides the controlled security-testing environment.

Purpose
  • Access the authorized laboratory server.
  • Execute the controlled credential-access scenario.
  • Validate detection.
  • Validate containment.

Virtualization Platform: VirtualBox

VirtualBox provides the isolated laboratory infrastructure.

Purpose
  • Host Ubuntu.
  • Host Kali Linux.
  • Isolate credential-access testing.
  • Prevent unintended interaction with production systems.

Process

STEP 01

Step 1: Prepare the Isolated SOC Laboratory

  • Create an isolated cybersecurity laboratory using VirtualBox.
  • Configure Ubuntu as the monitored Linux server.
  • Configure Kali Linux as the authorized security-testing system.
  • Establish an isolated virtual network.
  • Assign laboratory IP addresses.
  • Verify communication between the virtual machines.
  • Ensure the environment is separated from production systems.
Tools: VirtualBox + Ubuntu + Kali Linux
STEP 02

Step 2: Establish the Normal Authentication Baseline

  • Create a controlled laboratory user.
  • Create an authorized administrative user.
  • Review normal authentication-related files.
  • Review normal file permissions.
  • Perform legitimate user-management operations.
  • Record normal process and file-access activity.
  • Preserve the baseline for comparison.
Tools: Ubuntu + auditd
STEP 03

Step 3: Create the Protected Credential Test Environment

  • Create a harmless laboratory file representing authentication material.
  • Populate it only with synthetic credential values.
  • Apply restrictive permissions to the file.
  • Ensure the low-privileged test account cannot normally access it.
  • Record the file path and permissions.
  • Preserve the initial security state.
Tools: Python + Ubuntu
STEP 04

Step 4: Configure auditd Monitoring

  • Install and configure auditd.
  • Configure monitoring for the protected laboratory authentication file.
  • Configure relevant process-execution monitoring.
  • Configure user attribution.
  • Start the audit service.
  • Generate legitimate file activity.
  • Verify that audit events are generated.
Tools: auditd
STEP 05

Step 5: Deploy osquery

  • Install osquery on Ubuntu.
  • Verify that osquery is operational.
  • Configure the required endpoint queries.
  • Collect information about users and processes.
  • Verify that endpoint information is available.
  • Prepare osquery for investigation support.
Tools: osquery
STEP 06

Step 6: Deploy Wazuh Monitoring

  • Install the Wazuh agent on Ubuntu.
  • Register the agent with the Wazuh manager.
  • Configure collection of auditd events.
  • Configure collection of relevant endpoint telemetry.
  • Verify communication between Wazuh components.
  • Confirm that security events are received.
Tools: Wazuh
STEP 07

Step 7: Configure Credential-Dumping Detection

  • Define the conditions representing suspicious credential access.
  • Configure Wazuh rules for unauthorized access to the protected authentication test file.
  • Correlate file-access and process-execution events.
  • Include the accessing username.
  • Configure an appropriate alert severity.
  • Test the detection using legitimate administrative access.
  • Verify that authorized activity is not unnecessarily classified as credential dumping.
Tools: Wazuh
STEP 08

Step 8: Configure OpenSearch Investigation

  • Configure the Wazuh-to-OpenSearch integration.
  • Verify that security alerts are indexed.
  • Create searches for sensitive-file access.
  • Create filters for username and process.
  • Create filters for the protected file path.
  • Prepare the SOC investigation workflow.
Tools: Wazuh + OpenSearch
STEP 09

Step 9: Establish the SOC Detection Baseline

  • Generate legitimate administrative activity.
  • Review auditd events.
  • Review osquery endpoint information.
  • Review Wazuh alerts.
  • Review OpenSearch events.
  • Confirm that legitimate administrative access does not unnecessarily trigger the credential-dumping detection.
  • Record the normal detection baseline.
Tools: auditd + osquery + Wazuh + OpenSearch
STEP 10

Step 10: Initiate the Controlled Credential-Access Scenario

  • Log in using the controlled low-privileged laboratory account.
  • Attempt to access the protected credential test file.
  • Generate the predefined controlled access event.
  • Do not use real credential-extraction utilities.
  • Do not access real authentication material.
  • Record the activity timestamp.
  • Stop the test after sufficient telemetry is generated.
Tools: Kali Linux + Ubuntu + Python
STEP 11

Step 11: Capture the Credential-Access Events

  • Review auditd events.
  • Identify the accessing user.
  • Identify the accessed file.
  • Identify the process responsible for the access.
  • Review the process ID.
  • Review the parent process where available.
  • Preserve the generated audit telemetry.
Tools: auditd
STEP 12

Step 12: Detect the Credential-Dumping Activity

  • Allow Wazuh to process the collected events.
  • Identify the sensitive-file access event.
  • Identify the associated user.
  • Identify the associated process.
  • Compare the activity against the detection conditions.
  • Verify that Wazuh identifies the activity as suspicious.
  • Preserve the generated security alert.
Tools: Wazuh
STEP 13

Step 13: Generate the SOC Security Alert

  • Process the detected event through the Wazuh rule set.
  • Generate the corresponding security alert.
  • Record the affected Ubuntu server.
  • Record the account involved.
  • Record the protected file.
  • Record the process information.
  • Record the event timestamp.
  • Verify that the alert is visible to the SOC.
Tools: Wazuh
STEP 14

Step 14: Investigate the Credential-Dumping Alert

  • Open the Wazuh alert.
  • Review the event in OpenSearch.
  • Identify the user involved.
  • Identify the protected file.
  • Identify the process involved.
  • Review process information through osquery.
  • Review file permissions.
  • Compare the activity against the normal baseline.
  • Determine whether the event represents the controlled credential-dumping scenario.
Tools: Wazuh + OpenSearch + osquery + auditd
STEP 15

Step 15: Correlate the Complete Incident Timeline

  • Correlate the sensitive-file access with the process execution event.
  • Correlate auditd telemetry with Wazuh alerts.
  • Review osquery endpoint information.
  • Compare timestamps.
  • Compare username and process information.
  • Establish the complete SOC incident timeline.
  • Preserve the investigation evidence.
Tools: auditd + osquery + Wazuh + OpenSearch
STEP 16

Step 16: Execute Automated Response

  • Configure Wazuh Active Response for the confirmed credential-dumping alert.
  • Trigger the predefined response against the controlled laboratory account.
  • Temporarily restrict the account according to the laboratory response policy.
  • Record the response event.
  • Verify that the containment action is executed successfully.
Tools: Wazuh
STEP 17

Step 17: Validate Containment and Restore the Secure State

  • Attempt the controlled credential-access activity again using the restricted account.
  • Verify that access to the protected test file is prevented.
  • Restore the laboratory account to the required secure configuration.
  • Verify the protected file permissions.
  • Review auditd events.
  • Review Wazuh alerts.
  • Review OpenSearch telemetry.
  • Confirm that legitimate administrative activity remains functional.
Tools: Ubuntu + auditd + Wazuh + OpenSearch
STEP 18

Step 18: Perform Final SOC Detection and Response Validation

  • Repeat the controlled credential-dumping assessment.
  • Verify that auditd records the sensitive-file access.
  • Verify that osquery provides the required endpoint context.
  • Verify that Wazuh generates the expected security alert.
  • Verify that OpenSearch provides centralized investigation.
  • Verify automated response execution.
  • Confirm that containment prevents continued unauthorized credential access.
  • Confirm that legitimate administrative activity remains functional.
  • Review the complete incident timeline.
  • Document remaining detection gaps.
  • Finalize the SOC detection and response assessment.
Tools: auditd + osquery + Wazuh + OpenSearch + Python

Outcome

  1. A real Ubuntu Linux server is successfully deployed in an isolated SOC laboratory, providing a controlled environment for credential-access detection.
  2. A normal authentication and sensitive-file access baseline is established, allowing legitimate administrative activity to be distinguished from suspicious credential-access behavior.
  3. A controlled Linux credential-dumping scenario is safely reproduced using synthetic credential material, without accessing real passwords, password hashes, or production authentication information.
  4. auditd captures the sensitive-file access and associated process information, providing detailed endpoint audit evidence.
  5. osquery provides additional endpoint context about users, processes, and system state, supporting the SOC investigation.
  6. Wazuh correlates the endpoint security events and generates a centralized SOC alert, identifying the affected account, file, process, and security condition.
  7. OpenSearch enables centralized investigation and incident-timeline reconstruction, allowing analysts to correlate sensitive-file access, process activity, user identity, and timestamps.
  8. Wazuh Active Response initiates the configured containment mechanism, restricting the controlled laboratory account after suspicious credential-access activity is confirmed.
  9. Post-containment testing confirms that continued unauthorized credential access is prevented while legitimate administrative activity remains functional, validating the response mechanism.
  10. The complete Linux credential-dumping simulation, sensitive-file monitoring, auditd collection, osquery endpoint investigation, Wazuh SOC detection and alerting, OpenSearch investigation, incident correlation, automated containment, post-containment validation, and continuous SOC monitoring workflow is successfully demonstrated.
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