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MANSORY

Audit name:

[SCA] MANSORY | NFT Tier Staking | Jun2025

Date:

Jun 25, 2025

Table of Content

→Introduction
→Audit Summary
→System Overview
→Potential Risks
→Findings
→Appendix 1. Definitions
→Appendix 2. Scope
→Appendix 3. Additional Valuables
→Disclaimer

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Introduction

We express our gratitude to the MANSORY team for the collaborative engagement that enabled the execution of this Smart Contract Security Assessment.

Mansory's staking contract is a soul-bound NFT system where users lock ERC-20 tokens for a fixed duration to receive a non-transferable NFT that represents their stake and tier. Users can increase their stake to upgrade their tier, and the contract supports airdrops, tier-based metadata, and time-based withdrawals after expiry.

Document

NameSmart Contract Code Review and Security Analysis Report for MANSORY
Audited ByAtaberk Yavuzer, Konstantinidis Panagiotis
Approved ByIvan Bondar
Websitehttps://mansorytoken.io/→
Changelog19/06/2025 - Preliminary Report
25/06/2025 - Final Report
PlatformBSC
LanguageSolidity
TagsNon-fungible Token (NFT)
Methodologyhttps://hackenio.cc/sc_methodology→

  • Document

    Name
    Smart Contract Code Review and Security Analysis Report for MANSORY
    Audited By
    Ataberk Yavuzer, Konstantinidis Panagiotis
    Approved By
    Ivan Bondar
    Website
    https://mansorytoken.io/→
    Changelog
    19/06/2025 - Preliminary Report
    25/06/2025 - Final Report
    Platform
    BSC
    Language
    Solidity
    Tags
    Non-fungible Token (NFT)
    Methodology
    https://hackenio.cc/sc_methodology→

Review Scope

Contract Addresshttps://bscscan.com/address/0xa033ab0640ed86206aefa73db81b4ee659b7bde3#code→
Remediation Addresshttps://bscscan.com/address/0x88fa770e4408b8b5ef7b6d0d42d29d321a31b7a8#code→

Audit Summary

7Total Findings
5Resolved
0Accepted
2Mitigated

The system users should acknowledge all the risks summed up in the risks section of the report

Documentation quality

  • Functional requirements are included.

  • Technical description is provided.

Code quality

  • NatSpec is included across the contracts.

  • The code is clear and straightforward.

Test coverage

Code coverage of the project is 0% as no tests provided.

System Overview

The Mansory project implements a soul-bound NFT staking system designed to lock ERC-20 tokens in exchange for non-transferable NFTs that represent staking positions. The core functionality is encapsulated in the NftTierStakingUpgradeable contract, an upgradeable ERC-721 implementation that supports tiered staking, time-based locking, and controlled deposits by privileged users (airdrop role) on behalf of others.

Users can stake a specified ERC-20 token by locking it for a fixed duration (default: ~6 months). Upon staking, the user receives a non-transferable NFT that records the amount staked, the expiry timestamp, and the assigned tier based on the staked amount. Tiers are configurable and define thresholds and optional image metadata. Users can later deposit more tokens to upgrade their tier, but this will reset their expiry timestamp. After expiry, users can burn their own NFT to reclaim their total amount staked.

The contract includes an airdrop mechanism allowing privileged roles to create or top-up staking positions for multiple users in batch. It also supports external tokenUriBuilder contracts for dynamic NFT metadata generation.

Key attributes and design features:

  • ERC-20 staking token: Address set at initialization (name, symbol, decimals not defined in this contract)

  • ERC-721 token (soul-bound): Non-transferable NFTs with auto-incremented tokenIds starting from 1

  • Lock period: Uniform for all users, adjustable by the owner while the contract is paused

  • Tier structure: Configurable list of TierData entries, ordered by requireAmount

  • Upgradeable: Follows OpenZeppelin's TransparentUpgradeableProxy pattern

  • Role-based access control: Privileged airdrop role managed by the owner.

  • Contract status: Starts paused for safety, with administrative control over pausing, URI builder, and tier updates

This architecture enables secure token locking through non-transferable NFTs, supports transparent tier-based logic, and integrates customizable metadata for each tier position.

Privileged roles

The contract owner also holds administrative authority over critical system parameters, including:

  • Pausing and unpausing the contract (global circuit breaker)

  • Updating the lock duration (lockTime)

  • Modifying tier image URIs

  • Assigning or revoking airdrop roles

  • Setting or replacing the external tokenUriBuilder contract

  • Upgrading the contract through the proxy pattern (via ownership)

The airdrop role (onlyAirdropRole) is a privileged role that can:

  • Call the airdrop function to deposit tokens on behalf of users

Potential Risks

Dependency on External Logic for Implemented Functionality: Metadata generation and the contractURI() rely entirely on a separately deployed contract. This separation of responsibilities increases modularity but also adds external dependency risk—especially if the builder is upgraded or replaced with malicious logic.

System Reliance on External Contracts: The staking contract depends on an external tokenUriBuilder contract for rendering dynamic NFT metadata. Since this builder contract is not part of the audit scope, any vulnerabilities or failures in its logic could affect NFT display, user experience, or even lead to misleading token representations.

Owner’s Unrestricted State Modification: The contract grants the owner full control over key state parameters, including the ability to pause or unpause staking operations, change tier image URIs, and update the lock duration without delay or external approval. This flexibility allows quick reconfiguration but also exposes the system to potential misuse if the owner's account is compromised or misused internally.

Insufficient Multi-signature Controls for Critical Functions: No multi-signature requirement is enforced for critical owner-only functions, including upgrades and staking configuration changes. This centralizes decision-making power and increases the risk of unauthorized transactions or malicious actions being executed by a single compromised key.

Single Points of Failure and Control: The project is highly centralized, relying on a single owner address for executing critical administrative functions such as pausing and unpausing the contract, adjusting the global lock duration, modifying tier image, setting the external tokenUriBuilder contract, and managing airdrop roles. This concentration of power introduces significant operational risk in the event of private key compromise or mismanagement.

Absence of Time-lock Mechanisms for Critical Operations: Without time-locks on owner-only functions such as upgrades, lock duration changes, and role assignments, there is no buffer to review or revert potentially harmful actions, increasing the risk of rapid changes.

Flexibility and Risk in Contract Upgrades: The project's contracts are upgradable, allowing the administrator to update the contract logic at any time via OpenZeppelin’s proxy pattern. While this provides flexibility in addressing issues and evolving the project, it also introduces risks if the upgrade process is not properly governed or secured, potentially allowing unauthorized or malicious changes that could compromise the project's integrity and security.

Absence of Upgrade Window Constraints: The contract suite allows for immediate upgrades without a mandatory review or waiting period, increasing the risk of rapid deployment of malicious or flawed code, potentially compromising the system's integrity and user assets.

Findings

Code
―
Title
Status
Severity
F-2025-1105Missing Public View Function to Check NFT Expiry Status
fixed

Low
F-2025-1105Contradictions Between Documentation and Implementation Create Misleading Expectations
fixed

Low
F-2025-1105Failure to Handle Fee-On-Transfer Tokens Leads to Accounting Discrepancies
mitigated

Low
F-2025-1105Typographical Error in Documentation and Function Name May Cause Confusion
fixed

Observation
F-2025-1105Missing Check in setAidropRole Allows Zero Address Assignment
fixed

Observation
F-2025-1104Unused Custom Error
fixed

Observation
F-2025-1104Duplicated Looping in Airdrop Function Increases Gas Consumption
mitigated

Observation
1-7 of 7 findings

Identify vulnerabilities in your smart contracts.

Appendix 1. Definitions

Severities

When auditing smart contracts, Hacken is using a risk-based approach that considers Likelihood, Impact, Exploitability and Complexity metrics to evaluate findings and score severities.

Reference on how risk scoring is done is available through the repository in our Github organization:

Severity

Description

Critical
Critical vulnerabilities are usually straightforward to exploit and can lead to the loss of user funds or contract state manipulation.

High
High vulnerabilities are usually harder to exploit, requiring specific conditions, or have a more limited scope, but can still lead to the loss of user funds or contract state manipulation.

Medium
Medium vulnerabilities are usually limited to state manipulations and, in most cases, cannot lead to asset loss. Contradictions and requirements violations. Major deviations from best practices are also in this category.

Low
Major deviations from best practices or major Gas inefficiency. These issues will not have a significant impact on code execution.

  • Severity

    Critical

    Description

    Critical vulnerabilities are usually straightforward to exploit and can lead to the loss of user funds or contract state manipulation.

    Severity

    High

    Description

    High vulnerabilities are usually harder to exploit, requiring specific conditions, or have a more limited scope, but can still lead to the loss of user funds or contract state manipulation.

    Severity

    Medium

    Description

    Medium vulnerabilities are usually limited to state manipulations and, in most cases, cannot lead to asset loss. Contradictions and requirements violations. Major deviations from best practices are also in this category.

    Severity

    Low

    Description

    Major deviations from best practices or major Gas inefficiency. These issues will not have a significant impact on code execution.

Potential Risks

The "Potential Risks" section identifies issues that are not direct security vulnerabilities but could still affect the project’s performance, reliability, or user trust. These risks arise from design choices, architectural decisions, or operational practices that, while not immediately exploitable, may lead to problems under certain conditions. Additionally, potential risks can impact the quality of the audit itself, as they may involve external factors or components beyond the scope of the audit, leading to incomplete assessments or oversight of key areas. This section aims to provide a broader perspective on factors that could affect the project's long-term security, functionality, and the comprehensiveness of the audit findings.

Appendix 2. Scope

The scope of the project includes the following smart contracts from the provided repository:

Assets in Scope

NftTierStakingUpgradeable.sol - NftTierStakingUpgradeable.sol

Appendix 3. Additional Valuables

Verification of System Invariants

During the audit of Mansory, Hacken followed its methodology by performing fuzz-testing on the project's main functions. Echidna →, a tool used for fuzz-testing, was employed to check how the protocol behaves under various inputs. Due to the complex and dynamic interactions within the protocol, unexpected edge cases might arise. Therefore, it was important to use fuzz-testing to ensure that several system invariants hold true in all situations.

Fuzz-testing allows the input of many random data points into the system, helping to identify issues that regular testing might miss. A specific Echidna fuzzing suite was prepared for this task, and throughout the assessment, 9 invariants were tested over 10,000 runs. This thorough testing ensured that the system works correctly even with unexpected or unusual inputs .

Invariant Description

Test Result

Run Count

NFT must not be transferable (soul-bound)✅ Passed~10k
totalStaked cannot become negative✅ Passed~10k
Creating a lock below minimum tier must revert✅ Passed~10k
Withdraw before lock expiry must revert✅ Passed~10k
nextTokenId must always increment or stay the same✅ Passed~10k
Tier list must remain strictly ascending✅ Passed~10k
Creating a second lock must revert✅ Passed~10k
All NFTs must have a positive staked amount✅ Passed~10k
Withdraw must fail if called by an address not owning NFT✅ Passed~10k

  • Invariant Description

    NFT must not be transferable (soul-bound)

    Test Result

    ✅ Passed

    Run Count

    ~10k

    Invariant Description

    totalStaked cannot become negative

    Test Result

    ✅ Passed

    Run Count

    ~10k

    Invariant Description

    Creating a lock below minimum tier must revert

    Test Result

    ✅ Passed

    Run Count

    ~10k

    Invariant Description

    Withdraw before lock expiry must revert

    Test Result

    ✅ Passed

    Run Count

    ~10k

    Invariant Description

    nextTokenId must always increment or stay the same

    Test Result

    ✅ Passed

    Run Count

    ~10k

    Invariant Description

    Tier list must remain strictly ascending

    Test Result

    ✅ Passed

    Run Count

    ~10k

    Invariant Description

    Creating a second lock must revert

    Test Result

    ✅ Passed

    Run Count

    ~10k

    Invariant Description

    All NFTs must have a positive staked amount

    Test Result

    ✅ Passed

    Run Count

    ~10k

    Invariant Description

    Withdraw must fail if called by an address not owning NFT

    Test Result

    ✅ Passed

    Run Count

    ~10k

Additional Recommendations

The smart contracts in the scope of this audit could benefit from the introduction of automatic emergency actions for critical activities, such as unauthorized operations like ownership changes or proxy upgrades, as well as unexpected fund manipulations, including large withdrawals or minting events. Adding such mechanisms would enable the protocol to react automatically to unusual activity, ensuring that the contract remains secure and functions as intended.

To improve functionality, these emergency actions could be designed to trigger under specific conditions, such as:

  • Detecting changes to ownership or critical permissions.

  • Monitoring large or unexpected transactions and minting events.

  • Pausing operations when irregularities are identified.

These enhancements would provide an added layer of security, making the contract more robust and better equipped to handle unexpected situations while maintaining smooth operations.

Disclaimer