Mass Assignment (API)
In the context of API security, Mass Assignment refers to a specific functionality within an API that allows modifying multiple properties of an object with a single request. While it can be convenient for developers, it can also introduce security vulnerabilities if not implemented carefully.
Here's a breakdown of the critical aspects:
Object: An object represents a piece of data managed by the API, such as a user profile, a product listing, etc. Each object can have various properties with specific details (e.g., username, email, password for a user profile object).
Modification: Mass Assignment allows sending a single request to the API, including changes for multiple properties within the object.
Security Risk: The vulnerability arises when the API doesn't correctly validate or restrict which properties can be modified through mass assignment. This can allow attackers to exploit the functionality and potentially modify properties they shouldn't have access to.
How Mass Assignment Exploits Work:
Attackers can exploit Mass Assignment vulnerabilities in a few ways:
Unauthorized Modifications: If the API doesn't check permissions for each modified property, attackers might include additional properties in their request and change them without authorization. For example, an attacker could modify a user's email address or password in a user profile object.
Hidden Properties: Some APIs allow modifying hidden properties that aren't documented or exposed in the user interface. Attackers who discover these hidden properties through other means can exploit Mass Assignments to manipulate them maliciously.
Consequences of Mass Assignment Vulnerabilities:
Mass Assignment vulnerabilities can have serious consequences, including:
Privilege Escalation: Attackers might gain unauthorized access to higher privileges within the system by exploiting Mass Assignment to modify access control properties within objects.
Data Manipulation: Attackers can modify sensitive data within objects, potentially leading to disruption or fraud.
Account Takeover: In some cases, attackers might exploit Mass Assignment to modify critical properties and gain unauthorized control over user accounts.
Preventing Mass Assignment Vulnerabilities:
Here are some ways to avoid Mass Assignment vulnerabilities:
Implement Principle of Least Privilege: APIs should only allow modification of properties that are strictly necessary for the intended functionality.
Validate User Permissions: Ensure the API verifies user permissions for every modified property through Mass Assignment.
Allow listing: Instead of allowing the modification of any property, use allow listing to specify explicitly which properties can be changed through mass assignment.
Separate Update Endpoints: Consider using separate API endpoints for modifying specific properties instead of relying on a single mass assignment functionality.
Security Testing: Regularly test APIs for Mass Assignment vulnerabilities to identify and address potential weaknesses.
By following these practices, developers can significantly reduce the risk of vulnerabilities arising from Mass Assignment and ensure that only authorized modifications are possible within API objects.
Discovery: The First Step to Secure APIs
Identifying External APIs: ThreatNG excels at discovering external APIs with which your programs might interact. This is crucial because you can't address Mass Assignment vulnerabilities if you're unaware of the APIs using this functionality.
EASM and DRP: Building Intelligence
External Threat Monitoring: EASM continuously monitors the external landscape for newly discovered vulnerabilities impacting APIs. It helps stay informed about evolving threats related to Mass Assignment.
Digital Risk Protection: DRP provides valuable intelligence about known Mass Assignment vulnerabilities and best practices for secure updates within APIs. This knowledge allows you to prioritize security efforts based on the specific APIs.
Collaboration is Key: ThreatNG and Complementary Tools
ThreatNG works seamlessly with other solutions to create a robust defense against Mass Assignment vulnerabilities. Here's a positive handoff example:
ThreatNG Discovers and Identifies: ThreatNG discovers external APIs and identifies those your programs interact with.
Handoff to API Security Testing Tools: This information is passed on to dedicated API security testing tools, such as SAST (Static Application Security Testing) or DAST (Dynamic Application Security Testing) solutions.
Focused Testing for Mass Assignment: These tools analyze the API, focusing on how it handles updates to object properties. They can identify weaknesses like missing permission checks or the ability to modify unauthorized properties through Mass Assignment requests.
Remediation and Continuous Monitoring: Developers address identified vulnerabilities in the API, and ThreatNG's EASM continues monitoring for new threats.
Beyond Functionality and Access: A Holistic Approach
While ThreatNG helps identify APIs based on functionality and access (APIs handling sensitive data), a comprehensive approach goes further:
DRP Insights: ThreatNG's DRP can provide insights into specific Mass Assignment vulnerabilities associated with the discovered APIs. This knowledge empowers security testers to tailor their analysis to address known risks beyond functionality and access control checks. For example, DRP might reveal known vulnerabilities in popular API frameworks that can lead to Mass Assignment exploits.
Security Champions: ThreatNG can integrate with Security Development Lifecycle (SDL) tools, fostering a culture of security. Developers become aware of potential Mass Assignment risks from the beginning and can write code that validates user permissions and restricts unauthorized modifications during updates.
A strong security posture relies on collaboration. ThreatNG acts as the initial scout, discovering external APIs. It then works with developers, API security testing tools, and other solutions to create a layered defense that minimizes the risk of Mass Assignment vulnerabilities and ensures your APIs handle updates securely. By proactively identifying potential risks and collaborating with other tools, ThreatNG helps you stay ahead of attackers and secure your APIs.
