The Vault - Directed Stake Program - The Vault

Prepared by:

HALBORN

Last Updated 03/10/2025

Date of Engagement: February 6th, 2025 - February 10th, 2025

Summary

100% of all REPORTED Findings have been addressed

All findings

Critical

High

Medium

Low

Informational

1. Introduction
2. Assessment summary
3. Test approach and methodology
4. Risk methodology
5. Scope
6. Assessment summary & findings overview
7. Findings & Tech Details

7.1 Zero-copy struct representation
7.2 Use of non-checked spl token instructions

8. Automated Testing

1. Introduction

The Vault team engaged Halborn to conduct a security assessment on their Directed Stake and Directed Stake Token Solana programs beginning on February 6th, 2025, and ending on February, 10th, 2025. The security assessment was scoped to the Solana programs provided in SolanaVault/directed-stake GitHub repository. Commit hashes and further details can be found in the Scope section of this report.

The directed-stake program provides core functionality for managing a "Director" account that encapsulates staking parameters and target configurations on Solana. By initializing a Director PDA, users or programs can set a specific stake target (like a validator's vote account) and later update or close that Director. The program uses standard Solana/Anchor pattern such as PDA derivations and cross-program invocations (CPIs).

The directed-stake-token program integrates token minting, burning and fee distribution into the directed staking workflow. It allows the creation of a specialized "DST" (directed stake token) mint, which represents a liquidity token for staked assets. Users can deposit vSOL (a liquid staking token) in exchange for newly minted DST tokens, or burn DST tokens to withdraw staked assets minus fees.

2. Assessment Summary

Halborn was provided 4 days for the engagement and assigned one full-time security engineer to review the security of the Solana Program in scope. The engineer is a blockchain and smart contract security expert with advanced smart contract hacking skills, and deep knowledge of multiple blockchain protocols.

The purpose of the assessment is to:

Identify potential security issues within the Co-Staking Solana Program.
Ensure that the program's functionality operates as intended.

In summary, Halborn identified some improvements to reduce the likelihood and impact of risks, which were partially addressed by The Vault team:

Add #[repr(packed)] or #[repr(C)] directly above any #[account(zero_copy)] struct definitions to ensure a stable field layout across all builds.
Use checked SPL token methods for enhanced security and data integrity.

3. Test Approach and Methodology

Halborn performed a combination of a manual review of the source code and automated security testing to balance efficiency, timeliness, practicality, and accuracy in regard to the scope of the program assessment. While manual testing is recommended to uncover flaws in business logic, processes, and implementation; automated testing techniques help enhance coverage of programs and can quickly identify items that do not follow security best practices.

The following phases and associated tools were used throughout the term of the assessment:

Research into the architecture, purpose, and use of the platform.
Manual program source code review to identify business logic issues.
Mapping out possible attack vectors.
Thorough assessment of safety and usage of critical Rust variables and functions in scope that could lead to arithmetic vulnerabilities.
Scanning dependencies for known vulnerabilities (cargo audit).
Local runtime testing (solana-test-framework).

4. RISK METHODOLOGY

Every vulnerability and issue observed by Halborn is ranked based on two sets of Metrics and a Severity Coefficient. This system is inspired by the industry standard Common Vulnerability Scoring System.

The two Metric sets are: Exploitability and Impact. Exploitability captures the ease and technical means by which vulnerabilities can be exploited and Impact describes the consequences of a successful exploit.

The Severity Coefficients is designed to further refine the accuracy of the ranking with two factors: Reversibility and Scope. These capture the impact of the vulnerability on the environment as well as the number of users and smart contracts affected.

The final score is a value between 0-10 rounded up to 1 decimal place and 10 corresponding to the highest security risk. This provides an objective and accurate rating of the severity of security vulnerabilities in smart contracts.

The system is designed to assist in identifying and prioritizing vulnerabilities based on their level of risk to address the most critical issues in a timely manner.

4.1 EXPLOITABILITY

Attack Origin (AO):

Captures whether the attack requires compromising a specific account.

Attack Cost (AC):

Captures the cost of exploiting the vulnerability incurred by the attacker relative to sending a single transaction on the relevant blockchain. Includes but is not limited to financial and computational cost.

Attack Complexity (AX):

Describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Includes but is not limited to macro situation, available third-party liquidity and regulatory challenges.

Metrics:

EXPLOITABILITY METRIC ( $m_e$ )	METRIC VALUE	NUMERICAL VALUE
Attack Origin (AO)	Arbitrary (AO:A) Specific (AO:S)	1 0.2
Attack Cost (AC)	Low (AC:L) Medium (AC:M) High (AC:H)	1 0.67 0.33
Attack Complexity (AX)	Low (AX:L) Medium (AX:M) High (AX:H)	1 0.67 0.33

Exploitability

E

is calculated using the following formula:

$E = \prod m_e$

4.2 IMPACT

Confidentiality (C):

Measures the impact to the confidentiality of the information resources managed by the contract due to a successfully exploited vulnerability. Confidentiality refers to limiting access to authorized users only.

Integrity (I):

Measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of data stored and/or processed on-chain. Integrity impact directly affecting Deposit or Yield records is excluded.

Availability (A):

Measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. This metric refers to smart contract features and functionality, not state. Availability impact directly affecting Deposit or Yield is excluded.

Deposit (D):

Measures the impact to the deposits made to the contract by either users or owners.

Yield (Y):

Measures the impact to the yield generated by the contract for either users or owners.

Metrics:

IMPACT METRIC ( $m_I$ )	METRIC VALUE	NUMERICAL VALUE
Confidentiality (C)	None (I:N) Low (I:L) Medium (I:M) High (I:H) Critical (I:C)	0 0.25 0.5 0.75 1
Integrity (I)	None (I:N) Low (I:L) Medium (I:M) High (I:H) Critical (I:C)	0 0.25 0.5 0.75 1
Availability (A)	None (A:N) Low (A:L) Medium (A:M) High (A:H) Critical (A:C)	0 0.25 0.5 0.75 1
Deposit (D)	None (D:N) Low (D:L) Medium (D:M) High (D:H) Critical (D:C)	0 0.25 0.5 0.75 1
Yield (Y)	None (Y:N) Low (Y:L) Medium (Y:M) High (Y:H) Critical (Y:C)	0 0.25 0.5 0.75 1

Impact

I

is calculated using the following formula:

$I = max(m_I) + \frac{\sum{m_I} - max(m_I)}{4}$

4.3 SEVERITY COEFFICIENT

Reversibility (R):

Describes the share of the exploited vulnerability effects that can be reversed. For upgradeable contracts, assume the contract private key is available.

Scope (S):

Captures whether a vulnerability in one vulnerable contract impacts resources in other contracts.

Metrics:

SEVERITY COEFFICIENT ( $C$ )	COEFFICIENT VALUE	NUMERICAL VALUE
Reversibility ( $r$ )	None (R:N) Partial (R:P) Full (R:F)	1 0.5 0.25
Scope ( $s$ )	Changed (S:C) Unchanged (S:U)	1.25 1

Severity Coefficient

C

is obtained by the following product:

$C = rs$

The Vulnerability Severity Score

S

is obtained by:

$S = min(10, EIC * 10)$

The score is rounded up to 1 decimal places.

Severity	Score Value Range
Critical	9 - 10
High	7 - 8.9
Medium	4.5 - 6.9
Low	2 - 4.4
Informational	0 - 1.9

5. SCOPE

Files and Repository

(a) Repository: directed-stake

(b) Assessed Commit ID: 7441712

directed-stake/src/lib.rs
directed-stake-token/src/lib.rs
directed-stake-token/src/state.rs

↓ Expand ↓

Out-of-Scope: Third party dependencies and economic attacks.

Remediation Commit ID:

a6f438b

Out-of-Scope: New features/implementations after the remediation commit IDs.

6. Assessment Summary & Findings Overview

Critical

High

Medium

Low

Informational

Security analysis	Risk level	Remediation Date
Zero-Copy struct representation	Low	Solved - 02/21/2025
Use of non-checked SPL Token instructions	Informational	Acknowledged - 02/21/2025

7. Findings & Tech Details

7.1 Zero-Copy struct representation

Low

Description

In the directed-stake program, the Director struct is marked with #[account(zero_copy)], but does not appear to enforce a stable memory layout, via #[repr(C)] or #[repr(packed)]. The same applies to the DSTInfo struct in the directed-stake-token program (state.rs).

Without an explicit representation attribute, Rust may introduce unexpected alignment/padding, potentially leading to subtle data corruption or misalignment if the struct is extended or compiled under different settings.

Although current versions of the Rust compiler and Anchor typically behave predictably, it is generally recommended to pin down the struct's memory layout when using zero-copy. Failing to do so can become more critical when additional fields are introduced to the struct.

Code excerpts

directed-stake/programs/directed-stake/src/lib.rs

#[account(zero_copy)]
#[derive(Debug, Default)]
pub struct Director {
    pub stake_target: Pubkey,
    pub last_updated_at: u64,
}

directed-stake/programs/directed-stake-token/src/state.rs

#[account(zero_copy)]
#[derive(Debug, Default)]
pub struct DSTInfo {
    /// Mint account of the DST.
    pub token_mint: Pubkey,

    pub operator: Pubkey,
    pub partner: Pubkey,
    /// Where the vSOL tokens are stored.
    /// This also holds all fees.
    /// Note that fees are withdrawn in vSOL-- to withdraw the DST,
    /// chain the withdraw instruction with a mint instruction.
    pub vsol_reserves: Pubkey,

    // The lifetime amount of unclaimed operator fees
    pub lifetime_operator_fees: u64,
    // The total amount of operator fees not withdrawn from the DST.
    pub unclaimed_operator_fees: u64,

    // The lifetime amount of unclaimed partner fees
    pub lifetime_partner_fees: u64,
    // The total amount of partner fees not withdrawn from the DST.
    pub unclaimed_partner_fees: u64,

    /// Bump seed
    pub bump: u8,
    /// Base fee in BPS.
    pub base_fee: u8,
    /// Operator fee in BPS.
    pub operator_fee: u16,
    /// Padding to align the struct
    _padding: u32,

    /// An account which can become the new operator.
    pub pending_operator: Pubkey,
}

Proof of Concept

Steps:

Inspect the source code for the Director and DSTInfo struct definitions.
Confirm that #[repr(C)] or #[repr(packed)] is missing.
Optionally, try adding fields or building in a configuration to detect memory alignment/padding issues.

BVSS

AO:A/AC:L/AX:L/R:N/S:C/C:N/A:N/I:L/D:N/Y:N (3.1)

Recommendation

It is recommended to add #[repr(packed)] or #[repr(C)] directly above any #[account(zero_copy)] struct definitions to ensure a stable field layout across all builds.

If zero-copy is not strictly required, consider removing #[account(zero_copy)] and storing data in a normal Anchor account struct.

Remediation Comment

SOLVED: The Vault team has solved this issue as recommended. The commit hash for reference is a6f438b20507cb95c079afd2f4305852e5678763.

Remediation Hash

https://github.com/SolanaVault/directed-stake/commit/a6f438b20507cb95c079afd2f4305852e5678763

7.2 Use of non-checked SPL Token instructions

Informational

Description

During the review of the proposed Solana programs, it was identified that the standard, unchecked SPL token instructions are used, rather than their checked variation, specifically:

token::transfer(...)
token::mint_to(...)
token::burn(...)

The checked instructions, such as transfer_checked, mint_to_checked and burn_checked. These instructions include additional runtime assertions - such as verifying the expected token decimals - that go beyond the basic mint-matching checks performed by the standard instructions.

The checked instructions enforce the mint's declared decimal count during each operation, thereby reducing the chance of mismatch or incorrect decimal usage.

BVSS

AO:A/AC:L/AX:H/R:N/S:U/C:N/A:N/I:L/D:N/Y:N (0.8)

Recommendation

It is recommended to replace the unchecked instructions for their checked variants, such as mint_to_checked, transfer_checked and burn_checked.

Remediation Comment

ACKNOWLEDGED: The Vault team has acknowledged this finding.

8. Automated Testing

Static Analysis Report

Description

Halborn used automated security scanners to assist with detection of well-known security issues and vulnerabilities. Among the tools used was cargo audit, a security scanner for vulnerabilities reported to the RustSec Advisory Database. All vulnerabilities published in https://crates.io are stored in a repository named The RustSec Advisory Database. cargo audit is a human-readable version of the advisory database which performs a scanning on Cargo.lock. Security Detections are only in scope. All vulnerabilities shown here were already disclosed in the above report. However, to better assist the developers maintaining this code, the auditors are including the output with the dependencies tree, and this is included in the cargo audit output to better know the dependencies affected by unmaintained and vulnerable crates.

Cargo Audit Results

ID	Crate	Desccription
RUSTSEC-2024-0093	ed25519-dalek	Double Public Key Signing Function Oracle Attack on `ed255109-dalek`
RUSTSEC-2024-0344	curve25519-dalek	Timing variability in `curve25519-dalek`'s Scalar29::sub/Scalar52::sub
RUSTSEC-2024-0402	hashbrown	Borsh serialization of HashMap is non-canonical

Halborn strongly recommends conducting a follow-up assessment of the project either within six months or immediately following any material changes to the codebase, whichever comes first. This approach is crucial for maintaining the project’s integrity and addressing potential vulnerabilities introduced by code modifications.

1. Introduction
2. Assessment summary
3. Test approach and methodology
4. Risk methodology
5. Scope
6. Assessment summary & findings overview
7. Findings & Tech Details

7.1 Zero-copy struct representation
7.2 Use of non-checked spl token instructions

8. Automated Testing

// Download the full report

The Vault - Directed Stake Program

* Use Google Chrome for best results

** Check "Background Graphics" in the print settings if needed