CWE-1232: Improper Lock Behavior After Power State Transition

What is Improper Lock Behavior After Power State Transition?

• Overview: Improper Lock Behavior After Power State Transition (CWE-1232) is a vulnerability where system configuration registers, which should remain locked to prevent unauthorized changes, become modifiable after the system transitions between power states, such as entering or waking from low power modes.

• Exploitation Methods:

• Attackers can exploit this vulnerability by modifying system configurations when the lock protection is temporarily disabled during power state transitions.
• Common attack patterns include altering system settings or injecting malicious configurations when the registers are unintentionally left unprotected.

• Security Impact:

• Direct consequences of successful exploitation include unauthorized changes to critical system settings, potentially leading to system instability or exploitation of other vulnerabilities.
• Potential cascading effects may involve privilege escalation or bypassing security controls, leading to broader system compromise.
• Business impact includes potential data breaches, service disruptions, and loss of customer trust, which can result in financial and reputational damage.

• Prevention Guidelines:

• Specific code-level fixes include ensuring that lock bits are reapplied immediately after a power state transition to maintain register protection.
• Security best practices involve regular security audits, testing for power state transition vulnerabilities, and implementing secure boot processes.
• Recommended tools and frameworks include using hardware security modules (HSMs) or trusted platform modules (TPMs) to enforce register locks and employing software tools for automated security testing for power state vulnerabilities.

Corgea can automatically detect and fix Improper Lock Behavior After Power State Transition in your codebase. [Try Corgea free today](https://corgea.app).

Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not Technology-Specific

Vulnerable Code Example

import threading

class PowerStateManager:
    def __init__(self):
        self.lock = threading.Lock()
        self.config = {"setting": "default"}

    def enter_low_power_mode(self):
        # Acquire lock before entering low power mode
        self.lock.acquire()

    def wake_from_low_power_mode(self):
        # Improperly releasing lock without re-acquiring
        # after waking up, allowing config changes without protection
        self.lock.release()
        self.config["setting"] = "changed_unprotected"

Explanation:

• Line 10: The lock is acquired when entering low power mode to protect configuration settings.
• Line 14: Upon waking from low power mode, the lock is released without being re-acquired, leading to unprotected access to configuration settings. This can result in race conditions or unauthorized changes as the configuration is modified without the lock being held.

How to fix Improper Lock Behavior After Power State Transition?

To fix this issue, ensure that locks are correctly managed across power state transitions. The lock should be re-acquired after waking up from low power modes before making any changes to protected resources. This prevents unauthorized or accidental modifications to the system configuration.

Best Practices:

• Always ensure locks are properly managed and re-acquired when necessary, especially after transitions that may reset or alter lock states.
• Consider using context managers in Python (with statement) to handle lock acquisition and release automatically, reducing the risk of improper lock handling.

Fixed Code Example

import threading

class PowerStateManager:
    def __init__(self):
        self.lock = threading.Lock()
        self.config = {"setting": "default"}

    def enter_low_power_mode(self):
        # Acquire lock before entering low power mode
        self.lock.acquire()

    def wake_from_low_power_mode(self):
        # Re-acquire lock immediately after waking up
        with self.lock:
            # Protected modification of configuration
            self.config["setting"] = "changed_protected"

Explanation:

• Line 17: The lock is re-acquired immediately after waking from low power mode using a context manager (with self.lock:). This ensures that any modifications to the configuration are protected.
• Line 18: Configuration changes are made only while the lock is held, ensuring thread safety.
• Using a context manager simplifies the code by automatically handling lock acquisition and release, making it less error-prone and more robust against exceptions.