Solflare MetaMask Snaps - Solflare, Sui, Aptos

1 Executive Summary

This report presents the results of our engagement with Solflare Wallet to review three MetaMask Snaps, the aptos-snap for Rise Wallet, the solana-snap for Solflare, and the sui-snap for Elli Wallet.

The review was conducted from Aug 15, 2023 to July 25, 2023. A total of 9 person-days were spent.

2 Scope

The review focused on the following repositories and commit hashes:

• solflare-snap@792fcb2a253c572677271044ece061daae81ce41
• sui-snap@39740383fd11174a406a1a27e15c92f277d00779
• aptos-snap@36145fbb8f4963eb02cff26a549ac348a34d8cb3

The dapp wallets interfacing with the snap are not in scope of this review.

The list of files in scope can be found in the Appendix.

2.1 Objectives

Together with the client, we identified the following priorities for our review:

1. Correctness of the implementation, consistent with the intended functionality and without unintended edge cases.
2. Identify vulnerabilities particular to the MetaMask Snaps SDK integration in coherence with the MetaMask Snap Threat Model describing a Snap as an extension of the MetaMask Wallet Trust Module.

3 Snap Outlines

• The three snaps share certain parts of the codebase (duplications) and expose similar functionality to dapps.
  • ui.js - identical
  • privateKey.js - identical (ex. coinId)
  • index.js - logically similar: diff coinSpecifics, origin checks
  • utils.js - aptos with additional functions: hex2bytes, bytes2hex
  • auxfiles: logically similar
• The three snaps individually request sensitive BIP32 Entropy (SLIP-44), effectively managing the following coins private root key:
  • m/44'/501' (Solana)
  • m/44/784' (Sui)
  • m/44'/637' (Aptos)
• Connected dapps can communicate with the snap via MetaMask snap RPC. Dapp origins are enforced as follows:
  • Solana: localhost, *solflare.com, *solfalre.dev
  • Sui: localhost, *elliwallet.dev
  • Aptos: localhost, *risewallet.dev
• Other snaps cannot directly communicate with one of the three snaps under review.
• The public key is exposed to connected dapps without additional user confirmation if the dapp chooses so.
• The private key can not be exported to the RPC origin.
• Transactions/Messages are signed within the realm of the snap.
• The snap may display custom MetaMask dialogs.

3.1 Details: Solflare Snap

[🚀 == FsChecks == ]
    ℹ️  undefined
    🔺 - no linter config
[🚀 == Manifest == ]
    🔺 - bundle (dist/bundle.js) does not not exist!
🚨 -- Manifest errors --
    🔺 Error: Failed to read Snap bundle file: ENOENT: no such file or directory, open '/Users/tintin/workspace/solidity/solflare-wallet-snaps-audit-2023-08/solflare-snap/dist/bundle.js'
    🔺 - package.json: metamask template package.conf repo.url not correct 'undefined'
----%<---- raw permissions
🌐 : https://docs.metamask.io/snaps/reference/rpc-api/#wallet_requestsnaps
endowment:rpc { dapps: true, snaps: false }
snap_dialog {}
snap_getBip32Entropy [ { path: [ 'm', "44'", "501'" ], curve: 'ed25519' } ]
---->%---- raw permissions
🚜 [endowment:rpc]
    ❗- endowment:rpc.dapps - snap can communicate with websites/dapps; check origin for internal api calls!
       🔸  src/index.js
🚜 [snap_dialog]
    ☝️ - snap_dialog - Displays a dialog in the MetaMask UI. There are three types of dialogs with different parameters and return types.
    ⚠️ - this method renders Markdown! check for ctrlchar/markdown/injection
       🔸  src/ui.js
🚜 [snap_getBip32Entropy]
    ✨ - snap_getBip32Entropy - Gets the SLIP-10 key for the path and curve specified by the method name.
       ⚠️ - If you call this method, you receive the user's parent key for the derivation path they request. You're managing the user's keys and assets on their behalf. Their safety is your responsibility.
       🔸  src/privateKey.js
🌲 - Package Depenencies:
      - @babel/runtime:^7.21.5
      - @metamask/key-tree:^7.0.0                (🔺 looks like devDependency 👀)
      - @metamask/snaps-ui:^0.32.2               (🔺 looks like devDependency 👀)
      - bs58:^5.0.0
      - tweetnacl:^1.0.3
[🚀 == Bundle == ]
    🟢 Package.json OK
⚠️  Package.json Warnings:
    🔺 missing keywords
    🔺 missing bugs
    🔺 missing homepage
    🔺 missing repository

3.2 Details: Sui Snap

[🚀 == FsChecks == ]
    ℹ️  undefined
    🔺 - no linter config
[🚀 == Manifest == ]
    🔺 - bundle (dist/bundle.js) does not not exist!
🚨 -- Manifest errors --
    🔺 Error: Failed to read Snap bundle file: ENOENT: no such file or directory, open '/Users/tintin/workspace/solidity/solflare-wallet-snaps-audit-2023-08/sui-snap/dist/bundle.js'
    🔺 - package.json: metamask template package.conf repo.url not correct 'undefined'
----%<---- raw permissions
🌐 : https://docs.metamask.io/snaps/reference/rpc-api/#wallet_requestsnaps
endowment:rpc { dapps: true, snaps: false }
snap_dialog {}
snap_getBip32Entropy [ { path: [ 'm', "44'", "784'" ], curve: 'ed25519' } ]
---->%---- raw permissions
🚜 [endowment:rpc]
    ❗- endowment:rpc.dapps - snap can communicate with websites/dapps; check origin for internal api calls!
       🔸  src/index.js
🚜 [snap_dialog]
    ☝️ - snap_dialog - Displays a dialog in the MetaMask UI. There are three types of dialogs with different parameters and return types.
    ⚠️ - this method renders Markdown! check for ctrlchar/markdown/injection
       🔸  src/ui.js
🚜 [snap_getBip32Entropy]
    ✨ - snap_getBip32Entropy - Gets the SLIP-10 key for the path and curve specified by the method name.
       ⚠️ - If you call this method, you receive the user's parent key for the derivation path they request. You're managing the user's keys and assets on their behalf. Their safety is your responsibility.
       🔸  src/privateKey.js
🌲 - Package Depenencies:
      - @babel/runtime:^7.21.5
      - @metamask/key-tree:^7.0.0                (🔺 looks like devDependency 👀)
      - @metamask/snaps-ui:^0.32.2               (🔺 looks like devDependency 👀)
      - @noble/hashes:^1.3.1
      - base64-js:^1.5.1
      - tweetnacl:^1.0.3
[🚀 == Bundle == ]
    🟢 Package.json OK
⚠️  Package.json Warnings:
    🔺 missing keywords
    🔺 missing bugs
    🔺 missing homepage
    🔺 missing repository

3.3 Details: Aptos Snap

[🚀 == FsChecks == ]
    ℹ️  undefined
    🔺 - no linter config
[🚀 == Manifest == ]
    🔺 - bundle (dist/bundle.js) does not not exist!
🚨 -- Manifest errors --
    🔺 Error: Failed to read Snap bundle file: ENOENT: no such file or directory, open '/Users/tintin/workspace/solidity/solflare-wallet-snaps-audit-2023-08/aptos-snap/dist/bundle.js'
    🔺 - package.json: metamask template package.conf repo.url not correct 'undefined'
----%<---- raw permissions
🌐 : https://docs.metamask.io/snaps/reference/rpc-api/#wallet_requestsnaps
endowment:rpc { dapps: true, snaps: false }
snap_dialog {}
snap_getBip32Entropy [ { path: [ 'm', "44'", "637'" ], curve: 'ed25519' } ]
---->%---- raw permissions
🚜 [endowment:rpc]
    ❗- endowment:rpc.dapps - snap can communicate with websites/dapps; check origin for internal api calls!
       🔸  src/index.js
🚜 [snap_dialog]
    ☝️ - snap_dialog - Displays a dialog in the MetaMask UI. There are three types of dialogs with different parameters and return types.
    ⚠️ - this method renders Markdown! check for ctrlchar/markdown/injection
       🔸  src/ui.js
🚜 [snap_getBip32Entropy]
    ✨ - snap_getBip32Entropy - Gets the SLIP-10 key for the path and curve specified by the method name.
       ⚠️ - If you call this method, you receive the user's parent key for the derivation path they request. You're managing the user's keys and assets on their behalf. Their safety is your responsibility.
       🔸  src/privateKey.js
🌲 - Package Depenencies:
      - @babel/runtime:^7.21.5
      - @metamask/key-tree:^7.0.0                (🔺 looks like devDependency 👀)
      - @metamask/snaps-ui:^0.32.2               (🔺 looks like devDependency 👀)
      - tweetnacl:^1.0.3
[🚀 == Bundle == ]
    🟢 Package.json OK
⚠️  Package.json Warnings:
    🔺 missing keywords
    🔺 missing bugs
    🔺 missing homepage
    🔺 missing repository

4 Findings

Each issue has an assigned severity:

• Minor issues are subjective in nature. They are typically suggestions around best practices or readability. Code maintainers should use their own judgment as to whether to address such issues.
• Medium issues are objective in nature but are not security vulnerabilities. These should be addressed unless there is a clear reason not to.
• Major issues are security vulnerabilities that may not be directly exploitable or may require certain conditions in order to be exploited. All major issues should be addressed.
• Critical issues are directly exploitable security vulnerabilities that need to be fixed.

const { derivationPath, message, simulationResult = [], displayMessage = true } = request.params || {};

assertInput(derivationPath);
assertIsString(derivationPath);
assertInput(message);
assertIsString(message);
assertIsArray(simulationResult);
assertAllStrings(simulationResult);
assertIsBoolean(displayMessage);

const accepted = await renderSignTransaction(dappHost, message, simulationResult, displayMessage);
assertConfirmation(accepted);

    text(host),
    ...(simulationResultItems.length > 0 || displayMessage ? [divider()] : []),
    ...simulationResultItems,
    ...(displayMessage ? [copyable(message)] : [])
  ])
}

const { derivationPath, message, simulationResult = [], displayMessage = true } = request.params || {};

assertInput(derivationPath);
assertIsString(derivationPath);
assertInput(message);
assertIsString(message);
assertIsArray(simulationResult);
assertAllStrings(simulationResult);
assertIsBoolean(displayMessage);

const accepted = await renderSignTransaction(dappHost, message, simulationResult, displayMessage);
assertConfirmation(accepted);

export function renderSignTransaction(host, message, simulationResult, displayMessage = true) {
  const simulationResultItems = simulationResult.map((item) => text(item));

  return snap.request({
    method: 'snap_dialog',
    params: {
      type: 'confirmation',
      content: panel([
        heading('Sign transaction'),
        text(host),
        ...(simulationResultItems.length > 0 || displayMessage ? [divider()] : []),
        ...simulationResultItems,
        ...(displayMessage ? [copyable(message)] : [])
      ])
    }
  });
}

simulationResults[i].forEach((item) => uiElements.push(text(item)));
if (displayMessage) {
  uiElements.push(copyable(messages[i]));
}

const { derivationPath, message, simulationResult = [], displayMessage = true } = request.params || {};

assertInput(derivationPath);
assertIsString(derivationPath);
assertInput(message);
assertIsString(message);
assertIsArray(simulationResult);
assertAllStrings(simulationResult);
assertIsBoolean(displayMessage);

const accepted = await renderSignTransaction(dappHost, message, simulationResult, displayMessage);
assertConfirmation(accepted);

const { derivationPath, messages, simulationResults = [], displayMessage = true } = request.params || {};

assertInput(derivationPath);
assertIsString(derivationPath);
assertInput(messages);
assertIsArray(messages);
assertInput(messages.length);
assertAllStrings(messages);
assertIsArray(simulationResults);
assertInput(messages.length === simulationResults.length);
assertIsBoolean(displayMessage);

const accepted = await renderSignAllTransactions(dappHost, messages, simulationResults, displayMessage);
assertConfirmation(accepted);

const { derivationPath, message, simulationResult = [], displayMessage = true } = request.params || {};

assertInput(derivationPath);
assertIsString(derivationPath);
assertInput(message);
assertIsString(message);
assertIsArray(simulationResult);
assertAllStrings(simulationResult);
assertIsBoolean(displayMessage);

const accepted = await renderSignTransaction(dappHost, message, simulationResult, displayMessage);
assertConfirmation(accepted);

const { derivationPath, messages, simulationResults = [], displayMessage = true } = request.params || {};

assertInput(derivationPath);
assertIsString(derivationPath);
assertInput(messages);
assertIsArray(messages);
assertInput(messages.length);
assertAllStrings(messages);
assertIsArray(simulationResults);
assertInput(messages.length === simulationResults.length);
assertIsBoolean(displayMessage);

const accepted = await renderSignAllTransactions(dappHost, messages, simulationResults, displayMessage);
assertConfirmation(accepted);

case 'getPublicKey': {
  const { derivationPath, confirm = false } = request.params || {};

  assertInput(derivationPath);
  assertIsString(derivationPath);
  assertIsBoolean(confirm);

  const keyPair = await deriveKeyPair(derivationPath);

const segments = path.split('/').slice(3).filter(Boolean);

case 'getPublicKey': {
  const { derivationPath, confirm = false } = request.params || {};

  assertInput(derivationPath);
  assertIsString(derivationPath);
  assertIsBoolean(confirm);

  const keyPair = await deriveKeyPair(derivationPath);
  const pubkey = bs58.encode(keyPair.publicKey);

  if (confirm) {
    const accepted = await renderGetPublicKey(dappHost, pubkey);
    assertConfirmation(accepted);
  }

module.exports.onRpcRequest = async ({ origin, request }) => {
  if (
    !origin ||
    (
      !origin.match(/^https?:\/\/localhost:[0-9]{1,4}$/) &&
      !origin.match(/^https?:\/\/(?:\S+\.)?solflare\.com$/) &&
      !origin.match(/^https?:\/\/(?:\S+\.)?solflare\.dev$/)
    )
  ) {
    throw new Error('Invalid origin');
  }

module.exports.onRpcRequest = async ({ origin, request }) => {
  if (
    !origin ||
    (
      !origin.match(/^https?:\/\/localhost:[0-9]{1,4}$/) &&
      !origin.match(/^https?:\/\/(?:\S+\.)?risewallet\.dev$/)
    )
  ) {
    throw new Error('Invalid origin');
  }

module.exports.onRpcRequest = async ({ origin, request }) => {
  if (
    !origin ||
    (
      !origin.match(/^https?:\/\/localhost:[0-9]{1,4}$/) &&
      !origin.match(/^https?:\/\/(?:\S+\.)?elliwallet\.dev$/)
    )
  ) {
    throw new Error('Invalid origin');
  }

const getPrivkeyButton = document.querySelector('button.getPrivkey')

connectButton.addEventListener('click', connect)
getPrivkeyButton.addEventListener('click', getPrivkey)

async function getPrivkey () {
  try {
    const response = await ethereum.request({
      method: 'wallet_invokeSnap',
      params: {
        snapId,
        request: {
          method: 'getPublicKey',
          params: {
            derivationPath: `m/44'/501'/0'/0'`,
            confirm: true
          }
        }
      }
    })
    console.log(response);
  } catch (err) {
    console.error(err)
    alert('Problem happened: ' + err.message || err)
  }
}

"name": "@solflare-wallet/solana-snap",
"version": "1.0.0",
"description": "",
"main": "src/index.js",
"scripts": {
  "start": "mm-snap build && mm-snap serve",
  "build": "mm-snap build",
  "deploy": "npm run build && npm publish"
},
"author": "",
"license": "ISC",
"files": [

async function connect () {
  await ethereum.request({
    method: 'wallet_requestSnaps',
    params: { [snapId]: {} }
  })
}

Appendix 1 - Files in Scope

This review covered the following files:

Appendix 2 - Disclosure

Consensys Diligence (“CD”) typically receives compensation from one or more clients (the “Clients”) for performing the analysis contained in these reports (the “Reports”). The Reports may be distributed through other means, including via Consensys publications and other distributions.

The Reports are not an endorsement or indictment of any particular project or team, and the Reports do not guarantee the security of any particular project. This Report does not consider, and should not be interpreted as considering or having any bearing on, the potential economics of a token, token sale or any other product, service or other asset. Cryptographic tokens are emergent technologies and carry with them high levels of technical risk and uncertainty. No Report provides any warranty or representation to any third party in any respect, including regarding the bug-free nature of code, the business model or proprietors of any such business model, and the legal compliance of any such business. No third party should rely on the Reports in any way, including for the purpose of making any decisions to buy or sell any token, product, service or other asset. Specifically, for the avoidance of doubt, this Report does not constitute investment advice, is not intended to be relied upon as investment advice, is not an endorsement of this project or team, and it is not a guarantee as to the absolute security of the project. CD owes no duty to any third party by virtue of publishing these Reports.

A.2.1 Purpose of Reports

The Reports and the analysis described therein are created solely for Clients and published with their consent. The scope of our review is limited to a review of code and only the code we note as being within the scope of our review within this report. Any Solidity code itself presents unique and unquantifiable risks as the Solidity language itself remains under development and is subject to unknown risks and flaws. The review does not extend to the compiler layer, or any other areas beyond specified code that could present security risks. Cryptographic tokens are emergent technologies and carry with them high levels of technical risk and uncertainty. In some instances, we may perform penetration testing or infrastructure assessments depending on the scope of the particular engagement.

CD makes the Reports available to parties other than the Clients (i.e., “third parties”) on its website. CD hopes that by making these analyses publicly available, it can help the blockchain ecosystem develop technical best practices in this rapidly evolving area of innovation.

A.2.2 Links to Other Web Sites from This Web Site

You may, through hypertext or other computer links, gain access to web sites operated by persons other than Consensys and CD. Such hyperlinks are provided for your reference and convenience only, and are the exclusive responsibility of such web sites’ owners. You agree that Consensys and CD are not responsible for the content or operation of such Web sites, and that Consensys and CD shall have no liability to you or any other person or entity for the use of third party Web sites. Except as described below, a hyperlink from this web Site to another web site does not imply or mean that Consensys and CD endorses the content on that Web site or the operator or operations of that site. You are solely responsible for determining the extent to which you may use any content at any other web sites to which you link from the Reports. Consensys and CD assumes no responsibility for the use of third-party software on the Web Site and shall have no liability whatsoever to any person or entity for the accuracy or completeness of any outcome generated by such software.

A.2.3 Timeliness of Content

The content contained in the Reports is current as of the date appearing on the Report and is subject to change without notice unless indicated otherwise, by Consensys and CD.