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, above them a coverage table carrying a verdict for every pattern
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

Coverage Table

Report on every pattern in §6, whether or not it turned anything up. Emit this table above the findings, with all 6 rows present:

| # | Pattern | Verdict | Evidence | |---|---------|---------|----------| | 1 | Arbitrary CPI | n/a | this program makes no cross-program invocations | | 2 | Improper PDA Validation | | | | 3 | Missing Ownership Check | | | | 4 | Missing Signer Check | | | | 5 | Sysvar Account Check | | | | 6 | Improper Instruction Introspection | | |

Each verdict is one of:

• found — cite file:line and write the finding up in full below.
• clear — the pattern applies to this program and the program handles it. Name the constraint, account type, or check you searched for, so a reader can repeat the search.
• n/a — the pattern cannot apply here. Give the reason in one clause ("this program makes no CPI calls"). Not having looked is not n/a. Pattern 5 is version-scoped (pre-Solana 1.8.1): cite the solana-program version the program targets rather than dropping the row, since "targets 1.17, fixed upstream" and "did not look" are otherwise the same answer.

A table with fewer than 6 rows is an incomplete scan and must be reported as one. A row whose Verdict cell is empty is incomplete in the same way: row 1 above is filled in to show the shape, and every row is filled in the same way before the report is done. Six clear verdicts is a result a reader can act on. A report that covers two patterns and says nothing about the other four reads exactly like a clean program, and that is the failure this table exists to prevent.

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:
```rust
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

#[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
• [ ] Coverage table emitted with all 6 rows, each carrying a verdict of found, clear or n/a with a reason

---

13. Rationalizations to Reject

• "The program is small, so most patterns obviously don't apply." Obvious to whom? An n/a costs one clause and makes the judgment reviewable. Silence records nothing, and a reader cannot tell it apart from not having checked.
• "The Trail of Bits lints pass, so the program is clean." The lints cover a subset of these 6 patterns. A clean lint run is one row of evidence, not a verdict on the patterns it never examined. Say which patterns it covered.
• "I checked the patterns that matter for this program." Deciding which patterns matter is the scan, not a precondition for starting it. Rank by severity after the table is complete, not by leaving rows out.
• "No findings, so there is nothing to report." A zero-finding scan still emits the full coverage table. That table is the deliverable: it is what distinguishes a program that was examined from one that was glanced at.
• "Anchor handles account validation." Name the constraint. Anchor validates what the account struct declares and nothing more: #[account(mut)] is not an ownership check, and UncheckedAccount opts out entirely. Cite the attribute, not the framework.
• "The PDA derivation makes it safe." Derivation is not validation. create_program_address without the canonical bump admits multiple valid addresses, which is pattern 2 in full.