threat-modeling.md

Threat Model Analysis for fluent/fluentd

Threat: Log Injection Attacks

Description: An attacker crafts malicious log entries and injects them into log streams ingested by Fluentd. Fluentd, if not configured with proper input validation and sanitization, will process and forward these malicious logs. This can be done by exploiting vulnerabilities in applications generating logs or by directly injecting logs if input sources are not properly secured and Fluentd doesn't filter them.

Impact: Exploitation of vulnerabilities in downstream log processing systems (e.g., SIEM, log analysis tools) that receive logs forwarded by Fluentd, log poisoning leading to inaccurate analysis based on Fluentd's output, denial of service by overwhelming log pipelines managed by Fluentd, and potentially data breaches if injected logs contain malicious payloads that are executed by downstream systems processing Fluentd's output.

Affected Fluentd Component: Input Plugins, Parser Plugins, Filter Plugins (if processing injected data)

Risk Severity: High

Mitigation Strategies:

• Implement robust parsing and filtering in Fluentd to detect and discard suspicious log entries.
• Use structured logging formats (e.g., JSON) to make parsing and validation easier within Fluentd.
• Regularly update Fluentd and its plugins to patch known vulnerabilities that might be exploited via log injection.
• Consider using rate limiting on input sources within Fluentd to prevent log flooding attempts related to injection.
• Implement security monitoring and alerting for unusual log patterns or injection attempts detected by Fluentd.

Threat: Denial of Service (DoS) via Log Flooding

Description: An attacker floods Fluentd with an excessive volume of logs, overwhelming its processing capacity. Fluentd, if not properly configured with buffering and rate limiting, will attempt to process all incoming logs, leading to resource exhaustion. This can be achieved by compromising a log source or by directly sending a large number of logs to Fluentd's input.

Impact: Fluentd performance degradation, resource exhaustion (CPU, memory, disk) on the Fluentd server, service disruption for log aggregation and forwarding by Fluentd, and potential cascading failures in downstream systems relying on timely log data forwarded by Fluentd.

Affected Fluentd Component: Input Plugins, Buffer System, Core Fluentd Engine

Risk Severity: High

Mitigation Strategies:

• Implement rate limiting and traffic shaping within Fluentd input plugins.
• Configure Fluentd buffer settings appropriately to handle expected log volumes and bursts, preventing resource exhaustion.
• Monitor Fluentd resource usage (CPU, memory, disk I/O) and set up alerts for anomalies indicating potential DoS attacks targeting Fluentd.
• Use load balancing and horizontal scaling for Fluentd deployments to distribute load and handle high log volumes, mitigating DoS impact on a single Fluentd instance.

Threat: Data Exfiltration via Log Streams

Description: An attacker injects sensitive data (e.g., API keys, passwords, PII) into log messages with the intention of exfiltrating it through Fluentd's output destinations. Fluentd, if not configured to sanitize or mask sensitive data, will forward these logs containing sensitive information to configured outputs.

Impact: Confidential data leakage to unintended destinations via Fluentd's output streams, potential compromise of systems relying on the exfiltrated data (e.g., leaked API keys), and privacy violations due to Fluentd forwarding sensitive information.

Affected Fluentd Component: Input Plugins, Filter Plugins (if not properly masking sensitive data), Output Plugins

Risk Severity: High

Mitigation Strategies:

• Use Fluentd filter plugins to sanitize and mask sensitive data in logs before forwarding to output destinations.
• Encrypt log data in transit and at rest in output destinations configured in Fluentd.
• Regularly audit Fluentd configurations and logs processed by Fluentd for sensitive information leakage.

Threat: Configuration Vulnerabilities and Misconfigurations

Description: Incorrectly configured Fluentd settings, plugins, or parsers due to human error or lack of security awareness. This can lead to security breaches if, for example, output plugins are misconfigured to send logs to insecure destinations or input plugins are overly permissive.

Impact: Exposure of sensitive information due to misconfigured output destinations in Fluentd, bypass of security controls implemented within Fluentd, performance bottlenecks caused by inefficient configurations, and introduction of vulnerabilities exploitable by attackers through misconfigured Fluentd components.

Affected Fluentd Component: Configuration Files (fluent.conf, plugin configurations), Core Fluentd Engine, All Plugins

Risk Severity: High (for security-critical misconfigurations)

Mitigation Strategies:

• Follow security best practices for Fluentd configuration (least privilege, secure defaults).
• Use configuration management tools to enforce consistent and secure Fluentd configurations.
• Implement configuration validation and testing before deploying changes to Fluentd.
• Regularly review and audit Fluentd configurations for security vulnerabilities and misconfigurations.
• Use secure secrets management practices to handle sensitive credentials in Fluentd configurations (e.g., environment variables, secret stores).

Threat: Plugin Vulnerabilities (Input, Filter, Output, Parser)

Description: Security vulnerabilities in Fluentd plugins, including both core and community-contributed plugins. Attackers can exploit these vulnerabilities in plugins used by Fluentd to compromise the Fluentd server itself.

Impact: Remote code execution on the Fluentd server by exploiting plugin vulnerabilities, denial of service against Fluentd by triggering plugin flaws, information disclosure from the Fluentd server due to plugin weaknesses, privilege escalation on the Fluentd server through plugin exploits, and other malicious activities depending on the specific plugin vulnerability.

Affected Fluentd Component: All Plugin Types (Input, Filter, Output, Parser)

Risk Severity: Critical to High (depending on the vulnerability)

Mitigation Strategies:

• Use only trusted and well-maintained Fluentd plugins.
• Regularly update Fluentd and all installed plugins to the latest versions to patch known vulnerabilities.
• Subscribe to security advisories and vulnerability databases related to Fluentd and its plugins.
• Perform security testing and vulnerability scanning of Fluentd deployments, specifically focusing on plugin vulnerabilities.

Threat: Credential Exposure in Configuration Files

Description: Storing sensitive credentials (passwords, API keys, certificates) for output destinations or input sources directly in Fluentd configuration files in plaintext or easily reversible formats. If these configuration files are accessed by unauthorized individuals, the credentials used by Fluentd are compromised.

Impact: If configuration files are compromised, attackers can gain access to output destinations or input sources configured in Fluentd, potentially leading to data breaches, further system compromise through systems accessed by Fluentd, or unauthorized actions using compromised credentials managed by Fluentd.

Affected Fluentd Component: Configuration Files (fluent.conf, plugin configurations), Output Plugins, Input Plugins

Risk Severity: High

Mitigation Strategies:

• Never store sensitive credentials directly in Fluentd configuration files in plaintext.
• Use secure secrets management solutions (e.g., HashiCorp Vault, Kubernetes Secrets, environment variables) to store and manage credentials used by Fluentd.
• Reference credentials from secure secret stores in Fluentd configurations instead of embedding them directly.
• Implement strong access control for Fluentd configuration files to prevent unauthorized access.

Threat: Output Destination Compromise via Fluentd

Description: Attackers exploit vulnerabilities in Fluentd or its plugins to compromise output destinations that Fluentd is configured to send logs to. This could involve exploiting plugin vulnerabilities to gain unauthorized access or execute malicious code on output systems via Fluentd as an intermediary.

Impact: Compromise of output destinations connected to Fluentd, data breaches in output destinations, data manipulation or deletion in output destinations achieved through Fluentd, and potential use of compromised output destinations as a pivot point for further attacks on the infrastructure, initiated through Fluentd.

Affected Fluentd Component: Output Plugins, Core Fluentd Engine, Output Destinations themselves

Risk Severity: High

Mitigation Strategies:

• Apply all mitigations for plugin vulnerabilities and configuration vulnerabilities in Fluentd.
• Implement strong input validation and output sanitization in Fluentd plugins to prevent injection attacks targeting output destinations via Fluentd.
• Use least privilege principles for Fluentd's access to output destinations, limiting the potential damage if Fluentd is compromised.
• Monitor Fluentd's interactions with output destinations for suspicious activity that might indicate an attempted compromise.

Threat: Vulnerabilities in Fluentd Core Software

Description: Security vulnerabilities in the Fluentd core application itself. These vulnerabilities, if present, can be directly exploited by attackers targeting the Fluentd service.

Impact: Remote code execution on the Fluentd server due to core vulnerabilities, denial of service against Fluentd by exploiting core flaws, privilege escalation on the Fluentd server through core exploits, information disclosure from the Fluentd server, and other malicious activities depending on the nature of the core vulnerability.

Affected Fluentd Component: Core Fluentd Engine, Core Libraries

Risk Severity: Critical to High (depending on the vulnerability)

Mitigation Strategies:

• Always use the latest stable version of Fluentd to benefit from the latest security patches.
• Subscribe to Fluentd security advisories and vulnerability databases to stay informed about potential threats.
• Regularly update Fluentd to patch known vulnerabilities as soon as updates are available.
• Implement security testing and vulnerability scanning of Fluentd deployments to proactively identify potential weaknesses in the core software.