CWE-1268: Policy Privileges are not Assigned Consistently Between Control and Data Agents

What is Policy Privileges are not Assigned Consistently Between Control and Data Agents?

• Overview: This vulnerability arises when a system's hardware-enforced access control policies are not consistently applied between control agents (which manage policy settings) and data agents (which write data). This inconsistency can allow unauthorized access to sensitive resources by enabling untrusted agents to gain write privileges.

• Exploitation Methods:

• Attackers can exploit this by inserting a malicious agent into the write policy register, granting themselves unauthorized write access.
• Common attack patterns include manipulating policy settings or exploiting discrepancies to gain access to restricted resources.

• Security Impact:

• Direct consequences include unauthorized access to sensitive resources, leading to data leakage or corruption.
• Potential cascading effects involve the exposure of encryption keys, alteration of device configurations, and broader system compromise.
• Business impact includes potential data breaches, loss of customer trust, and regulatory non-compliance.

• Prevention Guidelines:

• Ensure that all access control policies are consistently applied across both control and data agents.
• Implement strict validation checks to prevent unauthorized changes to policy registers.
• Use secure boot mechanisms to validate firmware and software integrity.
• Regularly audit access control configurations to detect and rectify inconsistencies.
• Employ hardware security features that enforce strict separation between policy control and data writing functionalities.

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Technical Details

Likelihood of Exploit: Not specified

Affected Languages: Not Language-Specific

Affected Technologies: Not Technology-Specific

Vulnerable Code Example

class ResourceController:
    def __init__(self):
        # Control access policy is more restrictive
        self.control_policy = {"admin": True, "user": False}
        # Data access policy is more permissive
        self.data_policy = {"admin": True, "user": True}
    
    def access_resource(self, user_role):
        # Inconsistent policy check allows data access without control access
        if self.control_policy.get(user_role, False):
            return "Access Granted to Control Resource"
        elif self.data_policy.get(user_role, False):
            return "Access Granted to Data Resource"
        else:
            return "Access Denied"
        
# Example Usage
controller = ResourceController()
print(controller.access_resource("user"))  # Outputs: Access Granted to Data Resource

Vulnerability Explanation

The code above illustrates a security vulnerability due to inconsistent policy enforcement. The control_policy denies access to users with the role "user," while the data_policy allows it. This discrepancy means a user can access data resources without control permissions, potentially leading to unauthorized data access or modifications.

How to fix Policy Privileges are not Assigned Consistently Between Control and Data Agents?

To address this issue, implement a unified policy that ensures consistency between control and data access. Access should only be granted if both control and data permissions are satisfied, thereby preventing unauthorized access due to policy inconsistencies.

Fixed Code Example

class ResourceController:
    def __init__(self):
        # Unified policy structure for both control and data access
        self.policy = {
            "admin": {"control": True, "data": True},
            "user": {"control": False, "data": False}
        }
    
    def access_resource(self, user_role):
        # Unified policy check ensures consistent access control
        role_policy = self.policy.get(user_role, {"control": False, "data": False})
        if role_policy["control"] and role_policy["data"]:
            return "Access Granted to Control and Data Resources"
        else:
            return "Access Denied"

# Example Usage
controller = ResourceController()
print(controller.access_resource("user"))  # Outputs: Access Denied

Fix Explanation

The fixed code uses a unified policy structure that combines control and data access privileges into one cohesive policy. The access_resource method checks both control and data permissions, ensuring that a user can only access resources if they have both types of access. This approach mitigates the risk of privilege escalation and unauthorized access due to inconsistent policy application.