CWE-1320: Improper Protection for Outbound Error Messages and Alert Signals

What is Improper Protection for Outbound Error Messages and Alert Signals?

• Overview: Improper protection for outbound error messages and alert signals refers to a vulnerability where warning and alert signals from hardware sensors are not adequately protected, allowing unauthorized modifications or disabling of these alerts by untrusted entities, potentially leading to device malfunction or denial-of-service.

• Exploitation Methods:

• Attackers can intercept and modify alert signals to prevent them from triggering necessary responses.
• Common attack patterns include disabling alerts or generating false alarms to disrupt normal device operations.

• Security Impact:

• Direct consequences include the inability to respond to critical hardware conditions, potentially resulting in hardware damage.
• Potential cascading effects can include system instability, degraded performance, or complete system shutdown.
• Business impact involves increased maintenance costs, reduced reliability, and potential data loss or breaches due to system failures.

• Prevention Guidelines:

• Implement hardware-based mechanisms to secure alert signals, ensuring they cannot be tampered with by untrusted software.
• Follow security best practices by regularly updating and patching firmware and BIOS to protect against known vulnerabilities.
• Use recommended tools and frameworks that provide robust security features for monitoring and managing hardware sensors and alerts.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: System on Chip, Microcontroller Hardware, Memory Hardware, Power Management Hardware, Processor Hardware, Test/Debug Hardware, Sensor Hardware

Vulnerable Code Example

import logging

class AlertSystem:
    def __init__(self):
        self.alerts_enabled = True

    def trigger_alert(self, condition):
        if not self.alerts_enabled:
            # Alert disabled; the condition is not logged or handled
            return
        logging.warning(f"Alert: Condition {condition} exceeded limits!")

# Usage
alert_system = AlertSystem()
alert_system.alerts_enabled = False  # Alerts can be easily disabled from outside
alert_system.trigger_alert("Temperature")

Explanation:

• The alerts_enabled attribute is public and can be manipulated externally to disable alerts, allowing unauthorized entities to bypass the alert mechanisms. This poses a security risk as critical alerts can be suppressed without proper authorization.

How to fix Improper Protection for Outbound Error Messages and Alert Signals?

To fix this vulnerability, the alert system should ensure that alerts cannot be disabled by unauthorized external entities. This can be achieved by:

1. Making the alerts_enabled attribute private and only modifiable through controlled methods.
2. Implementing access controls to restrict who can change the alert configuration.
3. Logging any attempts to disable alerts to audit such actions.

Fixed Code Example

import logging

class AlertSystem:
    def __init__(self):
        self._alerts_enabled = True  # Make the alerts_enabled attribute private

    def enable_alerts(self):
        self._alerts_enabled = True

    def disable_alerts(self, user):
        # Add logging and authorization checks before disabling alerts
        logging.info(f"User {user} attempted to disable alerts")
        # Example authorization check (to be implemented properly in real-world cases)
        if not self._is_authorized(user):
            raise PermissionError("Unauthorized attempt to disable alerts")
        else:
            self._alerts_enabled = False

    def _is_authorized(self, user):
        # Placeholder for actual authorization logic
        # Return True if the user is authorized, otherwise False
        return user == "admin"

    def trigger_alert(self, condition):
        if not self._alerts_enabled:
            return
        logging.warning(f"Alert: Condition {condition} exceeded limits!")

# Usage
alert_system = AlertSystem()
# Direct modification is not allowed
# alert_system._alerts_enabled = False
try:
    alert_system.disable_alerts("user1")  # Unauthorized user
except PermissionError as e:
    logging.error(e)

alert_system.trigger_alert("Temperature")

Explanation:

• The alerts_enabled attribute is now _alerts_enabled, a private attribute, preventing external modification.
• Methods enable_alerts and disable_alerts are added to control the state of alerts safely.
• An authorization check is implemented in disable_alerts to ensure only authorized users can disable alerts.
• Logging attempts to change the alert state provides an audit trail for monitoring unauthorized access attempts.