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security: decrypt and sign dApp approvals in the popup (closes #157)
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The dApp transaction and signature approval paths sent the user's plaintext
password to the background over runtime.sendMessage and decrypted there. Both
now decrypt in the popup, where the password is typed, and put only the signed
artifact on the wire: the raw signed transaction, or the signature. Neither the
password, the recovery phrase, the xprv nor the private key crosses the
messaging boundary any more. This matches what the popup-side eth_sendTransaction
path in confirmTx.js already did.

The popup runs the same sequence ethers' own sendTransaction() runs internally
(populateTransaction, then signTransaction), so nonce, gas, fee and chain id
population are unchanged. The background keeps broadcast and approval
resolution, and when the popup cannot produce an artifact it reports the error
over the same message so the requesting page still gets a failure rather than
hanging.

Moving the secret out of the background must not turn the background into a
blind relay, so it re-derives the signer from the artifact and checks it
against the approval it is holding before acting: shared/approvalVerify.js
asserts that a raw transaction is the approved transaction signed by the
approved address, and that a signature covers the approved payload and recovers
to the approved address.

A wrong password is now caught in the popup before anything is sent, so it
fails with an inline full-sentence error and leaves the pending approval alive
to retry; previously it reached the background and destroyed the approval.
Rejection still resolves with EIP-1193 code 4001, and approvals still survive
popup close and reopen.

Removes the four standing TODO(security) markers, now that the flaw is gone.
This commit is contained in:
Jeffrey Paul
2026-08-09 02:50:50 +00:00
parent 188882d635
commit f37d52e04a
5 changed files with 712 additions and 123 deletions
Download Patch File Download Diff File Expand all files Collapse all files

107
src/background/index.js
View File

@@ -5,7 +5,6 @@
const { DEFAULT_RPC_URL } = require("../shared/constants");
const { SUPPORTED_CHAIN_IDS, networkByChainId } = require("../shared/networks");
const { onChainSwitch } = require("../shared/chainSwitch");
const { getBytes } = require("ethers");
const {
state,
loadState,
@@ -14,8 +13,7 @@ const {
} = require("../shared/state");
const { refreshBalances, getProvider } = require("../shared/balances");
const { debugFetch } = require("../shared/log");
const { decryptWithPassword } = require("../shared/vault");
const { getSignerForAddress } = require("../shared/wallet");
const { verifySignedTx, verifySignature } = require("../shared/approvalVerify");
const {
isPhishingDomain,
updatePhishingList,
@@ -725,39 +723,28 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
return true;
}
// The popup signs; it reports back here when it could not. Fail the
// request the same way this handler used to when it did the signing.
if (msg.error) {
approval.resolve({ error: { message: msg.error } });
sendResponse({ error: msg.error });
return false;
}
(async () => {
try {
await loadState();
const activeAddress = await getActiveAddress();
let wallet, addrIndex;
for (const w of state.wallets) {
for (let i = 0; i < w.addresses.length; i++) {
if (w.addresses[i].address === activeAddress) {
wallet = w;
addrIndex = i;
break;
}
}
if (wallet) break;
}
if (!wallet) throw new Error("Wallet not found");
// TODO(security): Move decryption to popup to avoid sending password via runtime.sendMessage
let decrypted = await decryptWithPassword(
wallet.encryptedSecret,
msg.password,
// The popup holds the secret, but the background stays the
// authority on what is broadcast: the raw transaction must be
// the approved one, signed by the approved address.
verifySignedTx(
msg.rawSignedTx,
approval.txParams,
activeAddress,
);
const signer = getSignerForAddress(
wallet,
addrIndex,
decrypted,
);
// Best-effort: clear decrypted secret after use.
// Note: JS strings are immutable; this nulls the reference but
// the original string may persist in memory until GC.
decrypted = null;
const provider = getProvider(state.rpcUrl);
const connected = signer.connect(provider);
const tx = await connected.sendTransaction(approval.txParams);
const tx = await provider.broadcastTransaction(msg.rawSignedTx);
approval.resolve({ txHash: tx.hash });
sendResponse({ txHash: tx.hash });
} catch (e) {
@@ -784,55 +771,23 @@ runtime.onMessage.addListener((msg, sender, sendResponse) => {
return true;
}
// The popup signs; it reports back here when it could not. Fail the
// request the same way this handler used to when it did the signing.
if (msg.error) {
approval.resolve({ error: { message: msg.error } });
sendResponse({ error: msg.error });
return false;
}
(async () => {
try {
await loadState();
const activeAddress = await getActiveAddress();
let wallet, addrIndex;
for (const w of state.wallets) {
for (let i = 0; i < w.addresses.length; i++) {
if (w.addresses[i].address === activeAddress) {
wallet = w;
addrIndex = i;
break;
}
}
if (wallet) break;
}
if (!wallet) throw new Error("Wallet not found");
// TODO(security): Move decryption to popup to avoid sending password via runtime.sendMessage
let decrypted = await decryptWithPassword(
wallet.encryptedSecret,
msg.password,
);
const signer = getSignerForAddress(
wallet,
addrIndex,
decrypted,
);
// Best-effort: clear decrypted secret after use.
// Note: JS strings are immutable; this nulls the reference but
// the original string may persist in memory until GC.
decrypted = null;
const sp = approval.signParams;
let signature;
if (sp.method === "personal_sign" || sp.method === "eth_sign") {
signature = await signer.signMessage(getBytes(sp.message));
} else {
// eth_signTypedData_v4 / eth_signTypedData
const typedData = JSON.parse(sp.typedData);
const { domain, types, message } = typedData;
// ethers handles EIP712Domain internally
delete types.EIP712Domain;
signature = await signer.signTypedData(
domain,
types,
message,
);
}
// The popup holds the secret, but the background stays the
// authority on what is handed back to the page: the signature
// must cover the approved payload and recover to the approved
// address.
const signature = msg.signature;
verifySignature(approval.signParams, signature, activeAddress);
approval.resolve({ signature });
sendResponse({ signature });
} catch (e) {