Solana Vulnerability Scanner

Solana Vulnerability Scanner

1. Purpose

Systematically scan Solana programs (native and Anchor framework) for platform-specific security vulnerabilities related to cross-program invocations, account validation, and program-derived addresses. This skill encodes 6 critical vulnerability patterns unique to Solana's account model.

2. When to Use This Skill

• Auditing Solana programs (native Rust or Anchor)
• Reviewing cross-program invocation (CPI) logic
• Validating program-derived address (PDA) implementations
• Pre-launch security assessment of Solana protocols
• Reviewing account validation patterns
• Assessing instruction introspection logic

3. Platform Detection

File Extensions & Indicators

• Rust files: .rs

Language/Framework Markers

// Native Solana program indicators
use solana_program::{
    account_info::AccountInfo,
    entrypoint,
    entrypoint::ProgramResult,
    pubkey::Pubkey,
    program::invoke,
    program::invoke_signed,
};

entrypoint!(process_instruction);

// Anchor framework indicators
use anchor_lang::prelude::*;

#[program]
pub mod my_program {
    pub fn initialize(ctx: Context<Initialize>) -> Result<()> {
        // Program logic
    }
}

#[derive(Accounts)]
pub struct Initialize<'info> {
    #[account(mut)]
    pub authority: Signer<'info>,
}

// Common patterns
AccountInfo, Pubkey
invoke(), invoke_signed()
Signer<'info>, Account<'info>
#[account(...)] with constraints
seeds, bump

Project Structure

• programs/*/src/lib.rs - Program implementation
• Anchor.toml - Anchor configuration
• Cargo.toml with solana-program or anchor-lang
• tests/ - Program tests

Tool Support

• Trail of Bits Solana Lints: Rust linters for Solana
• Installation: Add to Cargo.toml
• anchor test: Built-in testing framework
• Solana Test Validator: Local testing environment

4. How This Skill Works

When invoked, I will:

1. Search your codebase for Solana/Anchor programs
2. Analyze each program for the 6 vulnerability patterns
3. Report findings with file references and severity
4. Provide fixes for each identified issue
5. Check account validation and CPI security

5. Example Output

6. Vulnerability Patterns (6 Patterns)

I check for 6 critical vulnerability patterns unique to Solana. For detailed detection patterns, code examples, mitigations, and testing strategies, see VULNERABILITY_PATTERNS.md.

Pattern Summary:

1. Arbitrary CPI ⚠️ CRITICAL - User-controlled program IDs in CPI calls
2. Improper PDA Validation ⚠️ CRITICAL - Using create_program_address without canonical bump
3. Missing Ownership Check ⚠️ HIGH - Deserializing accounts without owner validation
4. Missing Signer Check ⚠️ CRITICAL - Authority operations without is_signer check
5. Sysvar Account Check ⚠️ HIGH - Spoofed sysvar accounts (pre-Solana 1.8.1)
6. Improper Instruction Introspection ⚠️ MEDIUM - Absolute indexes allowing reuse

For complete vulnerability patterns with code examples, see VULNERABILITY_PATTERNS.md.

7. Scanning Workflow

Step 1: Platform Identification

1. Verify Solana program (native or Anchor)
2. Check Solana version (1.8.1+ for sysvar security)
3. Locate program source (programs/*/src/lib.rs)
4. Identify framework (native vs Anchor)

Step 2: CPI Security Review

# Find all CPI calls
rg "invoke\(|invoke_signed\(" programs/

# Check for program ID validation before each
# Should see program ID checks immediately before invoke

For each CPI:

• Program ID validated before invocation
• Cannot pass user-controlled program accounts
• Anchor: Uses Program<'info, T> type

Step 3: PDA Validation Check

# Find PDA usage
rg "find_program_address|create_program_address" programs/
rg "seeds.*bump" programs/

# Anchor: Check for seeds constraints
rg "#\[account.*seeds" programs/

For each PDA:

• Uses find_program_address() or Anchor seeds constraint
• Bump seed stored and reused
• Not using user-provided bump

Step 4: Account Validation Sweep

# Find account deserialization
rg "try_from_slice|try_deserialize" programs/

# Should see owner checks before deserialization
rg "\.owner\s*==|\.owner\s*!=" programs/

For each account used:

• Owner validated before deserialization
• Signer check for authority accounts
• Anchor: Uses Account<'info, T> and Signer<'info>

Step 5: Instruction Introspection Review

# Find instruction introspection usage
rg "load_instruction_at|load_current_index|get_instruction_relative" programs/

# Check for checked versions
rg "load_instruction_at_checked|load_current_index_checked" programs/

• Using checked functions (Solana 1.8.1+)
• Using relative indexing
• Proper correlation validation

Step 6: Trail of Bits Solana Lints

# Add to Cargo.toml
[dependencies]
solana-program = "1.17"  # Use latest version

[lints.clippy]
# Enable Solana-specific lints
# (Trail of Bits solana-lints if available)

8. Reporting Format

Finding Template

## [CRITICAL] Arbitrary CPI - Unchecked Program ID

**Location**: `programs/vault/src/lib.rs:145-160` (withdraw function)

**Description**:
The `withdraw` function performs a CPI to transfer SPL tokens without validating that the provided `token_program` account is actually the SPL Token program. An attacker can provide a malicious program that appears to perform a transfer but actually steals tokens or performs unauthorized actions.

**Vulnerable Code**:
```rust
// lib.rs, line 145
pub fn withdraw(ctx: Context<Withdraw>, amount: u64) -> Result<()> {
    let token_program = &ctx.accounts.token_program;

    // WRONG: No validation of token_program.key()!
    invoke(
        &spl_token::instruction::transfer(...),
        &[
            ctx.accounts.vault.to_account_info(),
            ctx.accounts.destination.to_account_info(),
            ctx.accounts.authority.to_account_info(),
            token_program.to_account_info(),  // UNVALIDATED
        ],
    )?;
    Ok(())
}

Attack Scenario:

1. Attacker deploys malicious "token program" that logs transfer instruction but doesn't execute it
2. Attacker calls withdraw() providing malicious program as token_program
3. Vault's authority signs the transaction
4. Malicious program receives CPI with vault's signature
5. Malicious program can now impersonate vault and drain real tokens

Recommendation: Use Anchor's Program<'info, Token> type:

use anchor_spl::token::{Token, Transfer};

#[derive(Accounts)]
pub struct Withdraw<'info> {
    #[account(mut)]
    pub vault: Account<'info, TokenAccount>,
    #[account(mut)]
    pub destination: Account<'info, TokenAccount>,
    pub authority: Signer<'info>,
    pub token_program: Program<'info, Token>,  // Validates program ID automatically
}

pub fn withdraw(ctx: Context<Withdraw>, amount: u64) -> Result<()> {
    let cpi_accounts = Transfer {
        from: ctx.accounts.vault.to_account_info(),
        to: ctx.accounts.destination.to_account_info(),
        authority: ctx.accounts.authority.to_account_info(),
    };

    let cpi_ctx = CpiContext::new(
        ctx.accounts.token_program.to_account_info(),
        cpi_accounts,
    );

    anchor_spl::token::transfer(cpi_ctx, amount)?;
    Ok(())
}

References:

• building-secure-contracts/not-so-smart-contracts/solana/arbitrary_cpi
• Trail of Bits lint: unchecked-cpi-program-id

---

## 9. Priority Guidelines

### Critical (Immediate Fix Required)
- Arbitrary CPI (attacker-controlled program execution)
- Improper PDA validation (account spoofing)
- Missing signer check (unauthorized access)

### High (Fix Before Launch)
- Missing ownership check (fake account data)
- Sysvar account check (authentication bypass, pre-1.8.1)

### Medium (Address in Audit)
- Improper instruction introspection (logic bypass)

---

## 10. Testing Recommendations

### Unit Tests
```rust
#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    #[should_panic]
    fn test_rejects_wrong_program_id() {
        // Provide wrong program ID, should fail
    }

    #[test]
    #[should_panic]
    fn test_rejects_non_canonical_pda() {
        // Provide non-canonical bump, should fail
    }

    #[test]
    #[should_panic]
    fn test_requires_signer() {
        // Call without signature, should fail
    }
}

Integration Tests (Anchor)

import * as anchor from "@coral-xyz/anchor";

describe("security tests", () => {
  it("rejects arbitrary CPI", async () => {
    const fakeTokenProgram = anchor.web3.Keypair.generate();

    try {
      await program.methods
        .withdraw(amount)
        .accounts({
          tokenProgram: fakeTokenProgram.publicKey, // Wrong program
        })
        .rpc();

      assert.fail("Should have rejected fake program");
    } catch (err) {
      // Expected to fail
    }
  });
});

Solana Test Validator

# Run local validator for testing
solana-test-validator

# Deploy and test program
anchor test

11. Additional Resources

• Building Secure Contracts: building-secure-contracts/not-so-smart-contracts/solana/
• Trail of Bits Solana Lints: https://github.com/trailofbits/solana-lints
• Anchor Documentation: https://www.anchor-lang.com/
• Solana Program Library: https://github.com/solana-labs/solana-program-library
• Solana Cookbook: https://solanacookbook.com/

12. Quick Reference Checklist

Before completing Solana program audit:

CPI Security (CRITICAL):

• ALL CPI calls validate program ID before invoke()
• Cannot use user-provided program accounts
• Anchor: Uses Program<'info, T> type

PDA Security (CRITICAL):

• PDAs use find_program_address() or Anchor seeds constraint
• Bump seed stored and reused (not user-provided)
• PDA accounts validated against canonical address

Account Validation (HIGH):

• ALL accounts check owner before deserialization
• Native: Validates account.owner == expected_program_id
• Anchor: Uses Account<'info, T> type

Signer Validation (CRITICAL):

• ALL authority accounts check is_signer
• Native: Validates account.is_signer == true
• Anchor: Uses Signer<'info> type

Sysvar Security (HIGH):

• Using Solana 1.8.1+
• Using checked functions: load_instruction_at_checked()
• Sysvar addresses validated

Instruction Introspection (MEDIUM):

• Using relative indexes for correlation
• Proper validation between related instructions
• Cannot reuse same instruction across multiple calls

Testing:

• Unit tests cover all account validation
• Integration tests with malicious inputs
• Local validator testing completed
• Trail of Bits lints enabled and passing

Source: trailofbits/skills → plugins/building-secure-contracts/skills/solana-vulnerability-scanner/SKILL.md