threat-modeling.md

Threat Model Analysis for fuellabs/fuel-core

Threat: Consensus Failure (Byzantine Fault)

• Threat: Consensus Failure (Byzantine Fault)
  • Description: A sufficient number of validators (due to a bug in fuel-core's consensus logic or malicious coordination exploiting a weakness in the consensus mechanism) behave incorrectly, leading to a failure in the consensus mechanism. The attacker might collude with other validators to propose invalid blocks, stall the network, or create a fork. This is a direct fuel-core issue because the vulnerability lies within the consensus implementation.
  • Impact:
    • Network halt or fork, leading to loss of availability and potential double-spending.
    • Loss of user funds if a fork results in a chain rollback.
    • Damage to application reputation.
  • Affected Fuel-Core Component: fuel-core/src/consensus/ (specifically, the consensus algorithm implementation, including block production, validation, and finalization logic). This could also involve networking components in fuel-core/src/network/ if the attack involves message manipulation that exploits a vulnerability in the networking code.
  • Risk Severity: Critical
  • Mitigation Strategies:
    • (Network Level): Ensure a geographically diverse and decentralized set of validators (this mitigates the impact, but the vulnerability is still in fuel-core).
    • (Fuel Labs): Rigorous testing (including adversarial testing) and formal verification of the consensus algorithm. Audits of the consensus code. Rapid response to any reported consensus issues.
    • (Application Level): Monitor the network for signs of instability or forks. Implement logic to handle chain reorganizations gracefully. Wait for a sufficient number of confirmations before considering a transaction final (these are mitigations for the consequences, not the root cause).

Threat: Remote Code Execution (RCE) in fuel-core

• Threat: Remote Code Execution (RCE) in fuel-core
  • Description: An attacker exploits a vulnerability within fuel-core (e.g., in the P2P networking code, RPC server, or VM) to execute arbitrary code on the node. This could be achieved through a crafted message, a malicious transaction, or an exploit in a fuel-core dependency that fuel-core uses incorrectly. The key here is that the vulnerability originates within fuel-core or its direct interaction with dependencies.
  • Impact:
    • Complete compromise of the fuel-core node.
    • Theft of validator keys (if the node is a validator).
    • Manipulation of data sent to applications.
    • Denial of service.
    • Potential lateral movement to other systems.
  • Affected Fuel-Core Component: Potentially any component, but high-risk areas include:
    • fuel-core/src/network/ (P2P networking, message handling – vulnerabilities in parsing or handling network messages).
    • fuel-core/src/service/api/ (RPC server – vulnerabilities in request parsing or handling).
    • fuel-core/src/vm/ (virtual machine, instruction processing – vulnerabilities in bytecode interpretation or execution).
    • Anywhere external dependencies are used incorrectly by fuel-core (e.g., improper input sanitization before passing data to a dependency).
  • Risk Severity: Critical
  • Mitigation Strategies:
    • (Fuel Labs): Regular security audits and penetration testing, focusing on the components listed above. Fuzzing of input handling code (network messages, RPC requests, bytecode). Strict dependency management and vulnerability scanning, with a focus on how fuel-core uses those dependencies. Use of memory-safe languages (Rust) and secure coding practices.
    • (Node Operators): Keep fuel-core updated to the latest version (this addresses known vulnerabilities). Run the node with the least necessary privileges. Use a firewall to restrict access to the node. Monitor the node for suspicious activity (these are mitigations for the exploitation, not the vulnerability itself).

Threat: Denial of Service (DoS) against fuel-core Node due to internal vulnerabilities

• Threat: Denial of Service (DoS) against fuel-core Node due to internal vulnerabilities
  • Description: An attacker exploits a vulnerability within fuel-core to cause a denial of service. This is distinct from a generic network flood; the attacker sends specially crafted input (transactions, messages, API calls) that trigger a bug or resource exhaustion within fuel-core itself. For example, a malformed transaction that causes the VM to enter an infinite loop, or a specially crafted network message that triggers excessive memory allocation.
  • Impact:
    • The fuel-core node becomes unavailable.
    • Applications cannot interact with the Fuel network.
    • Loss of service for users.
    • Potential financial losses if time-sensitive operations are disrupted.
  • Affected Fuel-Core Component:
    • fuel-core/src/network/ (handling of incoming connections and messages – vulnerabilities in parsing or resource management).
    • fuel-core/src/service/api/ (RPC server, request handling – vulnerabilities in input validation or resource limits).
    • fuel-core/src/vm/ (transaction processing, resource limits – vulnerabilities in gas accounting, loop detection, or memory management).
    • Potentially the database layer (fuel-core/src/storage/) if the attack involves excessive storage writes due to a fuel-core bug.
  • Risk Severity: High
  • Mitigation Strategies:
    • (Fuel Labs): Implement robust input validation and sanitization in all relevant components. Implement strict resource quotas and limits (memory, CPU, storage). Design the node to be resilient to high load and handle errors gracefully. Thorough testing, including fuzzing and resource exhaustion testing.
    • (Node Operators): Keep fuel-core updated. Monitor network traffic and resource usage. Configure the node with appropriate resource limits (these are mitigations for the impact, but the vulnerability is in fuel-core).
    • (Application Level): Implement retry mechanisms with exponential backoff (mitigates the effect on the application).

Threat: Integer Overflow/Underflow in fuel-core's VM

• Threat: Integer Overflow/Underflow in fuel-core's VM
  • Description: An arithmetic operation within the fuel-core VM (during transaction execution) results in a value that is too large or too small to be represented by the data type, leading to unexpected behavior within the VM itself. This is a direct fuel-core issue because it's a vulnerability in the VM's implementation.
  • Impact:
    • Incorrect calculations within the VM, potentially leading to incorrect state updates on the blockchain.
    • Potentially exploitable vulnerabilities if the overflow/underflow leads to unexpected control flow within the VM.
    • Potential for denial of service if the overflow/underflow causes a panic within the VM.
  • Affected Fuel-Core Component:
    • fuel-core/src/vm/ (instruction execution, arithmetic operations – specifically, the implementation of arithmetic instructions and their handling of integer types).
  • Risk Severity: High
  • Mitigation Strategies:
    • (Fuel Labs): Ensure the VM uses checked arithmetic operations by default and handles overflow/underflow errors gracefully (e.g., by trapping rather than panicking). Rigorous testing of the VM's arithmetic operations, including edge cases and boundary conditions. Formal verification of the VM's arithmetic logic.

Threat: Replay Attack due to fuel-core bug

• Threat: Replay Attack due to fuel-core bug
  • Description: While replay attacks are often due to application-level errors, a bug within fuel-core could make replays possible. For example, if fuel-core incorrectly validates nonces or chain IDs, or if there's a flaw in how transactions are added to the mempool.
  • Impact:
    • Double-spending of funds.
    • Unintended execution of smart contract functions.
  • Affected Fuel-Core Component:
    • fuel-core/src/vm/ (transaction validation, nonce checking, chain ID verification)
    • fuel-core/src/txpool/ (transaction pool management - ensuring uniqueness and preventing re-inclusion of already-processed transactions)
  • Risk Severity: High
  • Mitigation Strategies:
    • (Fuel Labs): Rigorous testing of transaction validation logic, including nonce and chain ID checks. Ensure the transaction pool correctly handles duplicate transactions and prevents replays. Formal verification of relevant parts of the VM and transaction pool.