mitigations.md

Mitigation Strategies Analysis for fuellabs/sway

Mitigation Strategy: 1. Checked Arithmetic Implementation

• Mitigation Strategy: Checked Arithmetic Implementation
• Description:
  1. Identify Critical Arithmetic Operations in Sway Code: Review your Sway contract code and pinpoint all arithmetic operations (+, -, *, /, %, **), especially those dealing with user-provided inputs, external data, or financial calculations. These are prime locations for potential overflow or underflow issues.
  2. Utilize Sway's Checked Arithmetic Functions (if available): Check the Sway standard library and language features for built-in checked arithmetic functions or operators. If Sway provides functions like checked_add(), checked_sub(), etc., use them instead of standard operators for critical calculations. These functions typically return an Option or Result type, indicating success or failure (overflow/underflow).
  3. Implement Manual Overflow/Underflow Checks in Sway (if no built-in support): If Sway lacks native checked arithmetic for certain operations, implement manual checks directly in your Sway code. This involves:
     • Pre-computation Checks: Before performing an operation, add conditional logic in Sway to check if the operands are within a safe range to prevent overflow/underflow. For example, before adding a and b, check if MAX_VALUE - a < b (using Sway's comparison operators and constants if available).
     • Post-computation Checks: After performing an operation, use Sway's conditional statements to check if the result is within the expected range or if an overflow/underflow occurred based on the language's behavior.
  4. Sway Error Handling for Overflow/Underflow: When an overflow or underflow is detected in Sway, implement robust error handling. This should involve:
     • Using Sway's error handling mechanisms (e.g., Result type, panic! if appropriate for unrecoverable errors) to signal the error.
     • Reverting the transaction in Sway if the overflow/underflow compromises contract integrity.
     • Logging the error using Sway's logging capabilities (if available in the FuelVM context) for debugging and monitoring.
  5. Sway Unit Testing for Arithmetic Boundaries: Write comprehensive unit tests in Sway that specifically target overflow and underflow scenarios. Create Sway test cases that intentionally trigger these conditions to verify your mitigation strategy and error handling are working correctly within the Sway contract.
• Threats Mitigated:
  • Integer Overflow in Sway: (Severity: High) - Incorrect calculations in Sway due to overflow can lead to vulnerabilities like bypassing access controls, incorrect token balances, or unexpected contract behavior.
  • Integer Underflow in Sway: (Severity: High) - Similar to overflow, underflow in Sway can cause incorrect calculations and unexpected behavior, potentially leading to vulnerabilities in contract logic.
• Impact:
  • Integer Overflow: (Impact: High) - Effectively prevents vulnerabilities arising from integer overflows in critical arithmetic operations within Sway contracts.
  • Integer Underflow: (Impact: High) - Effectively prevents vulnerabilities arising from integer underflows in critical arithmetic operations within Sway contracts.
• Currently Implemented: Partially implemented in core Sway contract logic where sensitive calculations are performed. Often relies on manual checks in Sway as native checked arithmetic might be evolving in Sway.
• Missing Implementation: Systematic application across all arithmetic operations in Sway codebase, especially in less critical modules and utility functions. Waiting for more robust and easier-to-use native checked arithmetic support directly within the Sway language and standard library.

Mitigation Strategy: 2. Role-Based Access Control (RBAC) in Sway Contracts

• Mitigation Strategy: Role-Based Access Control (RBAC) in Sway Contracts
• Description:
  1. Define Sway Roles: Within the context of your Sway application, clearly define different user roles (e.g., Admin, Operator, Verifier, TokenMinter). Specify the exact permissions and functionalities each role should have access to within your Sway contracts.
  2. Implement Sway Role Management in Contracts: Design Sway contract structures and functions to manage roles. This could involve:
     • Using Sway's data structures (e.g., HashMap, StorageMap) to store mappings between user addresses (Sway Identity type) and their assigned roles.
     • Creating Sway functions (restricted to an initial admin role) to assign roles to users. These functions should modify the role mapping in Sway contract storage.
     • Developing Sway functions (admin-restricted) to revoke roles, updating the role mapping in Sway storage.
     • Implementing Sway functions to check if a given user (Sway Identity) possesses a specific role. These functions will be used for access control within other Sway contract functions.
  3. Enforce Sway Access Control with Function Modifiers/Checks: In your Sway contracts, for each function, determine the required role(s) for execution. Use Sway's function modifiers (if available and suitable) or explicit conditional checks at the start of functions to verify if the caller (using msg_sender() or similar Sway mechanism to get caller identity) has the necessary role. Use Sway's conditional logic (if, else) to control function execution based on role checks.
  4. Granular Sway Permissions: Design roles in Sway with granular permissions. Avoid overly broad roles. For example, instead of a single Admin role in Sway, consider roles like ContractUpgrader, ConfigurationManager, DataCustodian with specific responsibilities within the Sway contract.
  5. Sway Testing of RBAC Logic: Thoroughly test the RBAC implementation in your Sway contracts using Sway's testing framework. Write Sway unit tests to verify:
     • Correct role assignment and revocation through Sway functions.
     • Enforcement of access control in each Sway function based on different roles and user identities.
     • Handling of unauthorized access attempts in Sway functions, ensuring they are correctly rejected or handled.
     • Boundary and edge cases in Sway role management logic.
• Threats Mitigated:
  • Unauthorized Access to Sway Contract Functions: (Severity: High) - Prevents unauthorized users from executing sensitive functions within Sway contracts, protecting critical functionalities.
  • Privilege Escalation in Sway Contracts: (Severity: High) - Reduces the risk of users gaining elevated privileges within Sway contracts beyond their intended roles.
  • Data Manipulation by Unauthorized Users in Sway Contracts: (Severity: High) - Protects against unauthorized modification or deletion of critical data managed by Sway contracts.
• Impact:
  • Unauthorized Access: (Impact: High) - Significantly reduces the risk of unauthorized access to Sway contract functionalities by enforcing strict role-based access control.
  • Privilege Escalation: (Impact: Medium) - Reduces the risk, but proper role design and secure Sway role management implementation are crucial for full mitigation.
  • Data Manipulation by Unauthorized Users: (Impact: High) - Effectively prevents unauthorized data manipulation within Sway contracts through controlled access to data modification functions.
• Currently Implemented: Partially implemented for administrative functions and critical data modification operations in Sway contracts. A basic admin role is often defined and used for contract upgrades and configuration changes in Sway.
• Missing Implementation: Needs to be extended to more granular roles for different functionalities within Sway contracts. Currently, many Sway functions might rely on simpler authorization checks (e.g., owner-only), which should be refined with a more comprehensive RBAC system in Sway. User-facing functionalities in Sway contracts often lack robust role-based access control.

Mitigation Strategy: 3. Gas Limit Awareness and Loop Bounding in Sway

• Mitigation Strategy: Gas Limit Awareness and Loop Bounding in Sway
• Description:
  1. Analyze Sway Code for Computational Complexity: Carefully review your Sway contract code to identify computationally intensive operations, particularly loops (for, while) and recursive functions. Analyze the algorithmic complexity of these sections in your Sway code.
  2. Bound Loop Iterations in Sway: For all loops in your Sway contracts, ensure there are explicit and reasonable limits on the number of iterations. Avoid unbounded loops in Sway that could potentially run indefinitely and consume excessive resources. Use for loops with fixed ranges or while loops with clear exit conditions based on bounded variables within your Sway code.
  3. Optimize Sway Algorithms for Efficiency: Where possible, optimize algorithms within your Sway contracts to reduce their computational complexity. Consider using more efficient data structures or algorithms that are better suited for the FuelVM environment to perform operations with fewer resources.
  4. FuelVM Resource Consumption Monitoring (Sway Context): Utilize FuelVM's monitoring tools (if available) to analyze the resource consumption of your deployed Sway contracts. Identify resource-intensive functions and code sections within your Sway contracts and target them for optimization.
  5. Sway Testing with Stress Scenarios: Test your Sway contracts under stress conditions, simulating high load and complex operations. This helps identify potential Denial of Service (DoS) vulnerabilities related to resource exhaustion within your Sway contracts when deployed on FuelVM.
• Threats Mitigated:
  • Denial of Service (DoS) via FuelVM Resource Exhaustion from Sway Code: (Severity: High) - Prevents attackers from causing DoS by submitting transactions to your Sway contracts that consume excessive FuelVM resources due to unbounded loops or computationally expensive operations, leading to contract unavailability.
• Impact:
  • Denial of Service (DoS) via Gas Exhaustion: (Impact: High) - Significantly reduces the risk of DoS attacks against Sway contracts by limiting resource consumption within acceptable bounds through careful loop bounding and algorithm optimization in Sway code.
• Currently Implemented: General awareness during Sway contract development. Loops in critical sections of Sway code are usually bounded. Basic algorithm optimization is considered during Sway development.
• Missing Implementation: Systematic analysis of computational complexity across the entire Sway codebase. Formalized loop bounding practices and potentially automated checks within Sway development workflows. Deeper integration with FuelVM monitoring tools for resource profiling and optimization of Sway contracts. Stress testing specifically for DoS vulnerabilities in Sway contracts is not yet a standard practice.

Mitigation Strategy: 4. Reentrancy Prevention in Sway Cross-Contract Calls

• Mitigation Strategy: Reentrancy Prevention in Sway Cross-Contract Calls
• Description:
  1. Identify Sway Cross-Contract Calls: Thoroughly analyze your Sway contracts and pinpoint all instances where one Sway contract calls functions in another Sway contract. Pay close attention to the flow of control and data between these contracts.
  2. Minimize Sway State Changes After External Calls: Structure the logic of your Sway contracts to minimize or eliminate state changes after making external calls to other Sway contracts. Ideally, perform all necessary state updates within the calling Sway contract before initiating the external call.
  3. Implement Sway Reentrancy Guards/Mutex Patterns (if necessary): If state updates in the calling Sway contract must occur after external calls, implement reentrancy guards or mutex-like patterns directly within your Sway contract code to prevent re-entrant calls from disrupting state consistency. This could involve:
     • Using a Sway storage variable (e.g., a bool or enum) to track the execution status of the contract (e.g., locked, unlocked, in_call).
     • Adding checks at the beginning of critical Sway functions that are involved in cross-contract calls. These checks should verify the contract's execution status (e.g., is it unlocked?). Only allow function execution to proceed if the contract is in the expected state.
     • Setting the state to locked (or similar) in Sway before making an external call to another contract and then unlocking it (or resetting the state) after the external call returns. Ensure proper error handling in Sway to unlock even if the external call fails.
  4. Careful Ordering of Sway Operations: Within Sway functions involved in cross-contract calls, carefully order operations to avoid vulnerable call sequences. For example, update balances or critical state variables in your Sway contract before emitting events or making external calls to other contracts.
  5. Sway Testing for Reentrancy Vulnerabilities: Write dedicated unit tests in Sway specifically designed to test reentrancy scenarios in cross-contract calls. Simulate re-entrant calls to critical functions in your Sway contracts to verify that your implemented mitigation strategy effectively prevents unexpected behavior and maintains state integrity.
• Threats Mitigated:
  • Reentrancy Vulnerabilities in Sway Cross-Contract Interactions: (Severity: Medium - Lower in UTXO model compared to Account model, but still possible in certain scenarios within FuelVM) - Prevents attackers from exploiting reentrancy in Sway cross-contract calls to manipulate contract state in unintended ways, potentially leading to logical errors or unexpected contract behavior.
• Impact:
  • Reentrancy Vulnerabilities: (Impact: Medium) - Reduces the risk of reentrancy vulnerabilities in Sway contracts, especially in complex scenarios involving multiple cross-contract interactions. The UTXO model of FuelVM inherently mitigates some classic reentrancy risks, but careful Sway contract design and specific reentrancy prevention measures are still important for robust security.
• Currently Implemented: Awareness of reentrancy risks during Sway contract design. State updates in Sway contracts are generally prioritized before external calls where feasible.
• Missing Implementation: Formalized reentrancy guard patterns are not consistently applied across all Sway contracts. Dedicated reentrancy testing is not yet a standard part of the Sway contract testing process. More rigorous analysis of cross-contract call sequences in Sway contracts is needed to identify and mitigate potential reentrancy points.

Mitigation Strategy: 5. Compiler and Language-Specific Vulnerability Management for Sway

• Mitigation Strategy: Compiler and Language-Specific Vulnerability Management for Sway
• Description:
  1. Stay Updated with Sway and FuelVM Updates: Actively monitor the official Sway language and FuelVM project repositories, release notes, and community channels for announcements regarding updates, bug fixes, and security patches. Subscribe to relevant Sway and FuelVM newsletters or mailing lists.
  2. Regularly Update Sway Compiler and Tools: Establish a process for regularly updating the Sway compiler, SDK, and related development tools to the latest stable versions. This ensures you benefit from the most recent bug fixes, security improvements, and language enhancements in Sway.
  3. Report Sway Bugs and Potential Vulnerabilities: Actively participate in the Sway and FuelVM developer community. If you encounter suspected compiler bugs, unexpected language behavior, or potential security vulnerabilities in Sway or FuelVM, report them promptly and responsibly to the project maintainers through the appropriate channels (e.g., GitHub issue trackers, security reporting procedures).
  4. Utilize Sway-Specific Linters and Static Analysis Tools: As Sway-specific linters and static analysis tools become available, integrate them into your Sway development workflow. These tools can automatically detect potential coding errors, security vulnerabilities, and deviations from best practices directly within your Sway code during development.
  5. Thorough Testing Across Sway Compiler Versions: When developing and deploying Sway contracts, perform thorough testing across different Sway compiler versions (especially major and minor releases). This helps identify potential inconsistencies or version-specific bugs in the Sway compiler that could introduce vulnerabilities or unexpected behavior in your deployed Sway contracts.
• Threats Mitigated:
  • Sway Compiler Bugs Leading to Vulnerabilities: (Severity: Medium to High, depending on the bug) - Prevents vulnerabilities that could be introduced by bugs or flaws in the Sway compiler itself, which might lead to incorrect code generation or unexpected contract behavior.
  • Language-Specific Vulnerabilities in Sway: (Severity: Medium to High, depending on the vulnerability) - Mitigates risks associated with potential security vulnerabilities inherent in the design or implementation of the Sway language itself.
• Impact:
  • Sway Compiler Bugs Leading to Vulnerabilities: (Impact: Medium to High) - Reduces the risk of vulnerabilities stemming from compiler issues by staying updated and testing across versions.
  • Language-Specific Vulnerabilities in Sway: (Impact: Medium to High) - Proactively addresses potential language-level vulnerabilities by staying informed, reporting issues, and utilizing Sway-specific security tools.
• Currently Implemented: Awareness of the importance of using recent Sway compiler versions. Developers generally update Sway tools periodically.
• Missing Implementation: Formalized process for tracking Sway compiler updates and security advisories. Integration of Sway-specific linters and static analysis tools into the development pipeline is needed. Systematic testing across different Sway compiler versions is not yet a standard practice.

Mitigation Strategy: 6. Sway Contract-Specific Security Audits

• Mitigation Strategy: Sway Contract-Specific Security Audits
• Description:
  1. Engage Security Auditors with Sway Expertise: Before deploying Sway contracts to a production environment, engage reputable security auditors who possess specific expertise in Sway smart contract security and the FuelVM environment. Ensure auditors understand the nuances of Sway and potential Sway-specific vulnerabilities.
  2. Focus on Sway-Specific Vulnerability Areas: Direct security auditors to specifically focus on areas prone to Sway-related vulnerabilities, including:
     • Integer overflow/underflow vulnerabilities in Sway arithmetic operations.
     • Access control logic and RBAC implementation within Sway contracts.
     • Potential DoS vulnerabilities related to resource consumption in Sway code on FuelVM.
     • Reentrancy risks in Sway cross-contract calls and interactions.
     • Logic errors and unexpected behavior arising from Sway language features or compiler quirks.
     • Data validation and input sanitization within Sway contracts.
  3. Provide Auditors with Sway Contract Code and Specifications: Provide security auditors with complete and well-documented Sway contract source code, along with detailed specifications, architecture diagrams, and testing documentation. This enables auditors to thoroughly understand the intended functionality and identify potential security flaws in the Sway contracts.
  4. Address Audit Findings and Remediate Sway Code: Actively address all security vulnerabilities and issues identified by the auditors in their audit report. Remediate the Sway contract code based on the auditor's recommendations and best practices.
  5. Post-Audit Verification and Re-Audits (if necessary): After remediating the identified vulnerabilities, conduct internal verification testing to ensure the fixes are effective. Consider a follow-up audit or re-audit by the security auditors to confirm that all critical issues have been properly addressed and that the Sway contracts meet a sufficient security standard.
• Threats Mitigated:
  • Logic Errors and Unforeseen Vulnerabilities in Sway Contracts: (Severity: High) - Catches logic errors, design flaws, and unforeseen vulnerabilities in Sway contracts that might be missed during internal development and testing.
  • Sway-Specific Vulnerabilities Missed by General Security Practices: (Severity: Medium to High) - Identifies vulnerabilities that are specific to the Sway language, FuelVM, or the interaction between them, which might not be detected by general smart contract security practices.
• Impact:
  • Logic Errors and Unforeseen Vulnerabilities: (Impact: High) - Significantly reduces the risk of deploying Sway contracts with critical logic errors or vulnerabilities that could lead to financial loss, data breaches, or contract malfunctions.
  • Sway-Specific Vulnerabilities: (Impact: High) - Specifically mitigates the risk of Sway-specific vulnerabilities by leveraging expert auditors with focused Sway and FuelVM knowledge.
• Currently Implemented: Security audits are considered for major Sway contract deployments, but often general smart contract audits are performed without specific Sway expertise focus.
• Missing Implementation: Consistent engagement of security auditors with proven Sway and FuelVM expertise for all significant Sway contract deployments. Formalized process for Sway-specific audit scopes and vulnerability focus areas. Integration of security audit findings into the Sway development lifecycle and continuous improvement process.

Mitigation Strategy: 7. Rigorous Sway Contract Testing and Fuzzing

• Mitigation Strategy: Rigorous Sway Contract Testing and Fuzzing
• Description:
  1. Comprehensive Sway Unit Testing: Develop a comprehensive suite of unit tests for all Sway contracts. Unit tests should cover:
     • Normal execution paths and expected behavior of all Sway contract functions.
     • Edge cases, boundary conditions, and unusual input values for Sway functions.
     • Error handling logic and expected error conditions in Sway contracts.
     • Different user roles and access control scenarios within Sway contracts.
  2. Sway Integration Testing: Implement integration tests to verify the interactions between different Sway contracts and external systems (if applicable). Test cross-contract calls, data flow, and overall system behavior in a more integrated environment.
  3. Sway Fuzzing for Vulnerability Discovery: Utilize fuzzing techniques and tools (if available for Sway or adaptable to Sway/FuelVM) to automatically generate a wide range of inputs for Sway contract functions and identify potential vulnerabilities, crashes, or unexpected behavior. Fuzzing can help uncover edge cases and vulnerabilities that might be missed by manual testing.
  4. Sway Property-Based Testing: Explore property-based testing frameworks (if available for Sway) to define high-level properties that your Sway contracts should satisfy. Property-based testing automatically generates test cases to verify these properties and can uncover unexpected violations or logic errors in Sway contracts.
  5. Continuous Integration and Automated Sway Testing: Integrate Sway unit tests, integration tests, and fuzzing (if feasible) into a continuous integration (CI) pipeline. Automate the execution of these tests with every code change to ensure early detection of regressions and maintain a high level of code quality and security in your Sway contracts.
• Threats Mitigated:
  • Logic Errors and Bugs in Sway Contracts: (Severity: High) - Reduces the risk of deploying Sway contracts with logic errors, bugs, and unexpected behavior that could lead to vulnerabilities or contract failures.
  • Unforeseen Edge Cases and Input Combinations in Sway Contracts: (Severity: Medium to High) - Helps uncover vulnerabilities and unexpected behavior arising from unusual or malicious input combinations that might not be anticipated during manual testing of Sway contracts.
• Impact:
  • Logic Errors and Bugs: (Impact: High) - Significantly reduces the risk of deploying Sway contracts with logic errors and bugs through thorough and automated testing.
  • Unforeseen Edge Cases and Input Combinations: (Impact: Medium to High) - Proactively identifies and mitigates vulnerabilities related to edge cases and unexpected inputs by using fuzzing and comprehensive testing techniques for Sway contracts.
• Currently Implemented: Unit testing is practiced for core Sway contract functionalities. Basic integration testing might be performed manually. Fuzzing and property-based testing are not yet standard practices for Sway contracts.
• Missing Implementation: More comprehensive and systematic unit testing coverage for all Sway contract components. Development of robust integration test suites for Sway contracts. Exploration and adoption of fuzzing and property-based testing tools and techniques for Sway. Full integration of automated Sway testing into a CI/CD pipeline.