README.md

@@ -229,6 +229,7 @@ src/
     prices.js         — ETH/USD and token/USD via CoinDesk API
     scamlist.js       — known fraud contract addresses
     state.js          — persisted state (extension storage)
+    symbolSpoof.js    — the known-symbol spoof rule, shared by all surfaces
     tokenList.js      — top ERC-20 tokens by market cap (hardcoded)
     transactions.js   — tx history fetching + anti-poisoning filters
     uniswap.js        — Uniswap Universal Router calldata decoder
@@ -458,11 +459,12 @@ Which tokens an address shows is decided by `fetchTokenBalances()` in
 tokens do appear without the user adding them. An ERC-20 is shown when its
 balance is nonzero and it is in the bundled known-token list, is tracked by the
 user, or has 1,000 or more holders; a token claiming a symbol from the bundled
-list from any other contract address is always dropped. That filter is
-unconditional — the "Hide tokens with fewer than 1,000 holders" setting governs
-the transaction history and the send-screen token selector, not this list.
-Tracked tokens with a zero balance are listed as well while "Show tracked tokens
-with zero balance" is on.
+list from any other contract address is always dropped, and so is any token
+claiming a symbol that belongs to the native asset and therefore has no
+legitimate contract at all (`"ETH"`). That filter is unconditional — the "Hide
+tokens with fewer than 1,000 holders" setting governs the transaction history
+and the send-screen token selector, not this list. Tracked tokens with a zero
+balance are listed as well while "Show tracked tokens with zero balance" is on.
 
 #### Navigation
 
@@ -1280,14 +1282,15 @@ indexes it as a real token transfer.
   that is the only thing that populates it. In the transaction history the check
   is the "Hide fake tokens impersonating a known symbol" setting, on by default;
   with it off, spoofed transfers are shown and no new blocklist entries are
-  learned from them. The send-screen token selector applies the same check
-  unconditionally, because it decides which tokens the user can act on rather
-  than what the history displays. The balance list applies it unconditionally
-  too, but not identically: it exempts symbols that `KNOWN_SYMBOLS` maps to
-  `null`, and `"ETH"` is the only one. So the fake "Ethereum" token above is
-  filtered from the transaction history and from the send selector, but a
-  fake-`ETH` ERC-20 that clears the balance list's own 1,000-holder floor — or
-  that the user tracked manually — is still shown in the balance list.
+  learned from them. The send-screen token selector and the balance list apply
+  the same check unconditionally, because they decide which tokens the user can
+  act on and what the user believes they own rather than what the history
+  displays. All three surfaces read the rule from `src/shared/symbolSpoof.js`,
+  so they cannot answer the question differently. A symbol the list maps to no
+  contract at all — `"ETH"`, the native asset, is the only one — may be borne by
+  no contract, so every ERC-20 claiming it is a spoof on all three. The user's
+  real ETH balance is not an ERC-20 and is read over RPC, so the rule never sees
+  it.
 
 - **Low-holder token filtering**: Token transfers from ERC-20 contracts with
   fewer than 1,000 holders are hidden from transaction history by default.
@@ -1323,13 +1326,12 @@ indexes it as a real token transfer.
   a sharp tool — users who understand the risks can configure the wallet to show
   everything unfiltered, unix-style. All four settings govern the transaction
   history; what else each one reaches varies. The known-symbol check also runs
-  unconditionally on the send-screen token selector, and on the balance list
-  except for symbols mapped to `null` (`"ETH"` alone), which the balance list
-  does not filter. The fraud contract blocklist is applied unconditionally on
-  that selector and is not consulted by the balance list at all. The low-holder
-  setting also gates the send selector, while the balance list's own
-  1,000-holder floor is unconditional (see Data Model). The dust threshold
-  applies to the transaction history alone.
+  unconditionally on the send-screen token selector and on the balance list, in
+  both cases identically to the history. The fraud contract blocklist is applied
+  unconditionally on that selector and is not consulted by the balance list at
+  all. The low-holder setting also gates the send selector, while the balance
+  list's own 1,000-holder floor is unconditional (see Data Model). The dust
+  threshold applies to the transaction history alone.
 
 #### Phishing Domain Protection
 

TODO.md

@@ -44,6 +44,15 @@ undefined identifiers, which is how
 
 # Completed Steps
 
+- 2026-08-12: The known-symbol spoof rule moved into `src/shared/symbolSpoof.js`
+  and is now the only copy. The balance list had exempted symbols the token list
+  maps to `null` — `"ETH"` alone — so a fake ETH ERC-20 was hidden from the
+  transaction history and the Send selector but listed as a holding named ETH. A
+  symbol with no legitimate contract may now be borne by no contract on any of
+  the three surfaces, and the native exemption is "has no contract address", so
+  a second null-mapped symbol needs no call-site change. The user's real ETH
+  balance is read over RPC and never passes through the rule
+  ([#235](https://git.eeqj.de/sneak/AutistMask/issues/235)).
 - 2026-08-12: `script/verify-build`'s failure modes are now a committed target,
   `script/test-verify-build`, run by `make check`. It asserts the exit status
   and the message of every case against a fixture tree in a temp dir, and drops

src/popup/views/send.js

@@ -12,8 +12,9 @@ const {
 const { state, currentAddress } = require("../../shared/state");
 let ctx;
 const { getProvider } = require("../../shared/balances");
-const { KNOWN_SYMBOLS, resolveSymbol } = require("../../shared/tokenList");
+const { resolveSymbol } = require("../../shared/tokenList");
 const { isLowHolderCount } = require("../../shared/holders");
+const { isSpoofedSymbol } = require("../../shared/symbolSpoof");
 const { getAddress } = require("ethers");
 
 const ZERO_ADDRESS = "0x0000000000000000000000000000000000000000";
@@ -116,14 +117,6 @@ function updateToValidation() {
     }
 }
 
-function isSpoofedToken(t) {
-    const upper = (t.symbol || "").toUpperCase();
-    if (!KNOWN_SYMBOLS.has(upper)) return false;
-    const legit = KNOWN_SYMBOLS.get(upper);
-    if (legit === null) return true;
-    return t.address.toLowerCase() !== legit;
-}
-
 function renderSendTokenSelect(addr) {
     const sel = $("send-token");
     sel.innerHTML = '<option value="ETH">ETH</option>';
@@ -131,7 +124,7 @@ function renderSendTokenSelect(addr) {
         (state.fraudContracts || []).map((a) => a.toLowerCase()),
     );
     for (const t of addr.tokenBalances || []) {
-        if (isSpoofedToken(t)) continue;
+        if (isSpoofedSymbol(t.symbol, t.address)) continue;
         if (fraudSet.has(t.address.toLowerCase())) continue;
         // An unknown holder count does not withhold a token the user holds:
         // only a count the explorer actually reported as below the threshold

src/shared/balances.js

@@ -11,8 +11,9 @@ const {
 const { ERC20_ABI } = require("./constants");
 const { log, debugFetch } = require("./log");
 const { deriveAddressFromXpub } = require("./wallet");
-const { KNOWN_SYMBOLS, TOKEN_BY_ADDRESS } = require("./tokenList");
+const { TOKEN_BY_ADDRESS } = require("./tokenList");
 const { LOW_HOLDER_THRESHOLD, parseHoldersCount } = require("./holders");
+const { isSpoofedSymbol } = require("./symbolSpoof");
 
 // Use a static network to skip auto-detection (which can fail and cause
 // "could not coalesce error" on some RPC endpoints like Cloudflare).
@@ -89,15 +90,11 @@ async function fetchTokenBalances(address, blockscoutUrl, trackedTokens) {
             // Skip spam tokens the user never asked to see
             if (!isKnown && !isTracked && !hasEnoughHolders) continue;
 
-            // Skip tokens spoofing a known symbol from a different address
-            const sym = (item.token.symbol || "").toUpperCase();
-            const legitAddr = KNOWN_SYMBOLS.get(sym);
-            if (
-                legitAddr !== undefined &&
-                legitAddr !== null &&
-                tokenAddr !== legitAddr
-            )
-                continue;
+            // Skip tokens spoofing a known symbol from a different address.
+            // Every row here is an ERC-20 the explorer reported, so it has a
+            // contract address; the native ETH balance is fetched over RPC in
+            // refreshBalances and never passes through this loop.
+            if (isSpoofedSymbol(item.token.symbol, tokenAddr)) continue;
 
             balances.push({
                 address: item.token.address_hash,

src/shared/symbolSpoof.js

@@ -0,0 +1,43 @@
+// The known-symbol spoof rule, in one place.
+//
+// A token that borrows a known symbol from a contract that is not the one
+// that symbol belongs to is a spoof, and the wallet hides it.  Three surfaces
+// ask that question — the transaction history, the Send token selector and
+// the balance list — and they must answer it identically: a token the history
+// calls fake while the balance list lists it as a holding is worse than
+// either verdict alone, because the balance list is where the user forms
+// their belief about what they own (issue #235).
+//
+// KNOWN_SYMBOLS maps a symbol to the lowercased contract address that may
+// bear it, or to null.  Null means the symbol belongs to the native asset,
+// which has no contract at all, so no contract may bear it and every one
+// that does is a spoof.  "ETH" is the only such entry today; the rule is
+// written so that a second one needs no change here or at any call site.
+
+const { KNOWN_SYMBOLS } = require("./tokenList");
+
+// Ethereum addresses are case-insensitive: EIP-55 mixed case is a checksum
+// over the address, not part of its identity.
+function normalizeAddress(addr) {
+    return (addr || "").toLowerCase();
+}
+
+// True when a token bearing `symbol` from contract `contractAddress` is
+// impersonating a known symbol.
+//
+// An empty contract address is the native asset, which is never a spoof:
+// this is what keeps the user's real ETH out of the rule, and it holds for
+// any symbol that becomes null-mapped later, not just for ETH.
+function isSpoofedSymbol(symbol, contractAddress) {
+    const contract = normalizeAddress(contractAddress);
+    if (!contract) return false;
+    const sym = (symbol || "").toUpperCase();
+    if (!KNOWN_SYMBOLS.has(sym)) return false;
+    const legit = KNOWN_SYMBOLS.get(sym);
+    if (legit === null) return true;
+    return contract !== normalizeAddress(legit);
+}
+
+module.exports = {
+    isSpoofedSymbol,
+};

src/shared/transactions.js

@@ -8,8 +8,9 @@
 
 const { formatEther, formatUnits } = require("ethers");
 const { log, debugFetch } = require("./log");
-const { KNOWN_SYMBOLS, TOKEN_BY_ADDRESS } = require("./tokenList");
+const { TOKEN_BY_ADDRESS } = require("./tokenList");
 const { parseHoldersCount, isLowHolderCount } = require("./holders");
+const { isSpoofedSymbol } = require("./symbolSpoof");
 
 // Ethereum addresses are case-insensitive: EIP-55 mixed case is a checksum
 // over the address, not part of its identity.  Every address comparison in
@@ -245,18 +246,6 @@ async function fetchRecentTransactions(address, blockscoutUrl, count = 25) {
     return result;
 }
 
-// Check if a token transfer is spoofing a known symbol.
-// Returns true if the symbol matches a known token but the contract
-// address doesn't match the legitimate one.
-function isSpoofedSymbol(tx) {
-    if (!tx.contractAddress) return false;
-    const symbol = (tx.symbol || "").toUpperCase();
-    if (!KNOWN_SYMBOLS.has(symbol)) return false;
-    const legit = KNOWN_SYMBOLS.get(symbol);
-    if (legit === null) return true; // "ETH" as ERC-20 is always fake
-    return normalizeAddress(tx.contractAddress) !== normalizeAddress(legit);
-}
-
 // Pure filter function. Takes raw transactions and filter settings,
 // returns { transactions, newFraudContracts }.
 function filterTransactions(txs, filters = {}) {
@@ -283,7 +272,7 @@ function filterTransactions(txs, filters = {}) {
         const contract = normalizeAddress(tx.contractAddress);
 
         // Filter spoofed known symbols and record the fraud contract
-        if (hideSpoofed && isSpoofedSymbol(tx)) {
+        if (hideSpoofed && isSpoofedSymbol(tx.symbol, tx.contractAddress)) {
             if (contract && !fraudSet.has(contract)) {
                 fraudSet.add(contract);
                 newFraud.push(contract);

tests/symbolSpoof.test.js

@@ -0,0 +1,296 @@
+// Tests for the known-symbol spoof rule (src/shared/symbolSpoof.js) and for
+// its application on all three surfaces that show tokens: the transaction
+// history, the Send token selector, and the balance list.
+//
+// Issue #235: the three surfaces disagreed about what a `null` entry in
+// KNOWN_SYMBOLS means.  The history and the selector read it as "no contract
+// may bear this symbol" and filtered a fake `ETH` ERC-20; the balance list
+// read it as "no comparison is possible" and listed the fake token next to
+// the user's real ETH, which is where a user forms their belief about what
+// they own.  The rule now lives in one module, so a fourth surface cannot
+// reintroduce a fourth reading, and these tests assert the same attack on
+// each surface.
+//
+// Nothing here touches the network: global.fetch is a throwing stub and the
+// only fetch path in the modules under test (debugFetch, from
+// src/shared/log) is mocked at the module boundary.
+
+// The RPC provider is replaced so that refreshBalances can be driven end to
+// end: the native balance it reports must survive a balance list in which
+// every ERC-20 row is a fake ETH.  Everything else in ethers is the real
+// module, including the formatters the assertions depend on.
+jest.mock("ethers", () => {
+    const actual = jest.requireActual("ethers");
+    class StubProvider {
+        async getBalance() {
+            return 1234500000000000000n;
+        }
+        async lookupAddress() {
+            return null;
+        }
+    }
+    return {
+        ...actual,
+        JsonRpcProvider: StubProvider,
+        Network: { from: () => ({}) },
+    };
+});
+
+jest.mock("../src/shared/log", () => ({
+    log: {
+        debugf: () => {},
+        infof: () => {},
+        warnf: () => {},
+        errorf: () => {},
+    },
+    debugFetch: jest.fn(),
+    setRuntimeDebug: () => {},
+    isDebug: () => false,
+}));
+
+global.fetch = jest.fn(() => {
+    throw new Error("tests must not perform network requests");
+});
+global.chrome = {
+    storage: { local: { get: async () => ({}), set: async () => {} } },
+};
+
+const { isSpoofedSymbol } = require("../src/shared/symbolSpoof");
+const { KNOWN_SYMBOLS } = require("../src/shared/tokenList");
+const { filterTransactions } = require("../src/shared/transactions");
+const {
+    fetchTokenBalances,
+    refreshBalances,
+} = require("../src/shared/balances");
+const { renderSendTokenSelect } = require("../src/popup/views/send");
+const { state } = require("../src/shared/state");
+const { debugFetch } = require("../src/shared/log");
+
+// The fake "Ethereum" token with symbol "ETH" from the attack documented in
+// README.md, given a holder count high enough to clear every other filter so
+// that only the known-symbol rule can catch it.
+const FAKE_ETH_CONTRACT = "0xd05339f9ea5ab9d9f03b9d57f671d2abd1f55c82";
+const HOLDER = "0x66133e8ea0f5d1d612d2502a968757d1048c214a";
+const USDC_CONTRACT = "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48";
+const WETH_CONTRACT = "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2";
+const BLOCKSCOUT = "https://eth.blockscout.com/api/v2";
+
+describe("the shared rule", () => {
+    test('"ETH" is still the null-mapped symbol these tests assume', () => {
+        expect(KNOWN_SYMBOLS.get("ETH")).toBeNull();
+    });
+
+    test("a contract bearing a null-mapped symbol is a spoof", () => {
+        expect(isSpoofedSymbol("ETH", FAKE_ETH_CONTRACT)).toBe(true);
+    });
+
+    test("even a genuine contract may not bear a null-mapped symbol", () => {
+        expect(isSpoofedSymbol("ETH", WETH_CONTRACT)).toBe(true);
+    });
+
+    test("the native asset carries no contract and is never a spoof", () => {
+        expect(isSpoofedSymbol("ETH", null)).toBe(false);
+        expect(isSpoofedSymbol("ETH", undefined)).toBe(false);
+        expect(isSpoofedSymbol("ETH", "")).toBe(false);
+    });
+
+    // The native exemption is "has no contract address", not "the symbol is
+    // ETH".  A second null-mapped symbol added to the table later inherits
+    // both halves of the rule without any call site being revisited.
+    test("a newly null-mapped symbol behaves the same way", () => {
+        const added = !KNOWN_SYMBOLS.has("XTZTEST");
+        KNOWN_SYMBOLS.set("XTZTEST", null);
+        try {
+            expect(isSpoofedSymbol("XTZTEST", FAKE_ETH_CONTRACT)).toBe(true);
+            expect(isSpoofedSymbol("XTZTEST", null)).toBe(false);
+        } finally {
+            if (added) KNOWN_SYMBOLS.delete("XTZTEST");
+        }
+    });
+
+    test("a known symbol from its own contract is not a spoof", () => {
+        expect(isSpoofedSymbol("USDC", USDC_CONTRACT)).toBe(false);
+        expect(isSpoofedSymbol("usdc", USDC_CONTRACT.toUpperCase())).toBe(
+            false,
+        );
+    });
+
+    test("a known symbol from another contract is a spoof", () => {
+        expect(isSpoofedSymbol("USDC", FAKE_ETH_CONTRACT)).toBe(true);
+    });
+
+    test("a symbol that is not in the table is not judged here", () => {
+        expect(isSpoofedSymbol("SPAMTKN", FAKE_ETH_CONTRACT)).toBe(false);
+    });
+});
+
+describe("surface 1: the transaction history", () => {
+    function fakeEthTransfer() {
+        return {
+            hash: "0x" + "1".repeat(64),
+            symbol: "ETH",
+            contractAddress: FAKE_ETH_CONTRACT,
+            holders: 900000,
+            valueGwei: null,
+            isContractCall: false,
+        };
+    }
+
+    test("a fake ETH token transfer is filtered", () => {
+        const result = filterTransactions([fakeEthTransfer()], {
+            hideSpoofedSymbols: true,
+            hideFraudContracts: true,
+            hideLowHolderTokens: true,
+            hideDustTransactions: true,
+            dustThresholdGwei: 100000,
+        });
+        expect(result.transactions).toEqual([]);
+    });
+
+    test("a real native ETH transfer survives", () => {
+        const native = {
+            hash: "0x" + "2".repeat(64),
+            symbol: "ETH",
+            contractAddress: null,
+            holders: null,
+            valueGwei: 5000000,
+            isContractCall: false,
+        };
+        const result = filterTransactions([native], {
+            hideSpoofedSymbols: true,
+            hideFraudContracts: true,
+            hideLowHolderTokens: true,
+            hideDustTransactions: true,
+            dustThresholdGwei: 100000,
+        });
+        expect(result.transactions).toEqual([native]);
+    });
+});
+
+describe("surface 2: the Send token selector", () => {
+    let select;
+
+    function render(tokenBalances) {
+        select = { innerHTML: "", children: [] };
+        select.appendChild = (child) => select.children.push(child);
+        globalThis.document = {
+            getElementById: (id) => (id === "send-token" ? select : null),
+            createElement: () => ({ value: "", textContent: "" }),
+        };
+        renderSendTokenSelect({
+            address: "0x" + "a".repeat(40),
+            tokenBalances,
+        });
+    }
+
+    beforeEach(() => {
+        state.fraudContracts = [];
+        state.hideLowHolderTokens = true;
+    });
+
+    test("a fake ETH token is not selectable", () => {
+        render([
+            {
+                address: FAKE_ETH_CONTRACT,
+                symbol: "ETH",
+                decimals: 18,
+                balance: "0.005",
+                holders: 900000,
+            },
+        ]);
+        expect(select.children).toEqual([]);
+    });
+
+    test("native ETH remains the always-present option", () => {
+        render([]);
+        expect(select.innerHTML).toBe('<option value="ETH">ETH</option>');
+    });
+});
+
+describe("surface 3: the balance list", () => {
+    function respondWith(items) {
+        debugFetch.mockImplementation(async () => ({
+            ok: true,
+            status: 200,
+            statusText: "OK",
+            json: async () => items,
+        }));
+    }
+
+    function fakeEthItem(overrides = {}) {
+        return {
+            value: "5000000000000000",
+            token: {
+                type: "ERC-20",
+                address_hash: FAKE_ETH_CONTRACT,
+                symbol: "ETH",
+                name: "Ethereum",
+                decimals: "18",
+                holders_count: "900000",
+                ...overrides,
+            },
+        };
+    }
+
+    beforeEach(() => {
+        debugFetch.mockReset();
+    });
+
+    // The bug in issue #235: this token cleared the balance list's own
+    // 1,000-holder floor and was listed as a holding named ETH.
+    test("a fake ETH token clearing the holder floor is filtered", async () => {
+        respondWith([fakeEthItem()]);
+        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, [])).toEqual([]);
+    });
+
+    test("tracking the fake token manually does not admit it either", async () => {
+        respondWith([fakeEthItem({ holders_count: "0" })]);
+        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, [
+            { address: FAKE_ETH_CONTRACT },
+        ]);
+        expect(balances).toEqual([]);
+    });
+
+    test("a genuine token keeps its place in the list", async () => {
+        respondWith([
+            fakeEthItem({
+                address_hash: USDC_CONTRACT,
+                symbol: "USDC",
+                name: "USD Coin",
+                decimals: "6",
+            }),
+        ]);
+        const balances = await fetchTokenBalances(HOLDER, BLOCKSCOUT, []);
+        expect(balances).toHaveLength(1);
+        expect(balances[0].symbol).toBe("USDC");
+    });
+
+    // The trap in this change: the user's real ETH balance is not an ERC-20
+    // and is fetched over RPC in refreshBalances, so it never passes through
+    // this loop at all.  An explorer row that is not an ERC-20 is dropped
+    // before the symbol rule is consulted.
+    test("a non-ERC-20 row claiming ETH never reaches the symbol rule", async () => {
+        respondWith([fakeEthItem({ type: "ERC-721" })]);
+        expect(await fetchTokenBalances(HOLDER, BLOCKSCOUT, [])).toEqual([]);
+    });
+
+    // The money test: the user holds real ETH and has been airdropped a fake
+    // ETH ERC-20.  The fake is gone from the list of tokens; the real balance
+    // is exactly what the node reported.
+    test("the real native ETH balance survives a fake ETH airdrop", async () => {
+        respondWith([fakeEthItem()]);
+        const addr = { address: HOLDER };
+        await refreshBalances(
+            [{ addresses: [addr] }],
+            "https://rpc.example.invalid",
+            BLOCKSCOUT,
+            [],
+        );
+        expect(addr.balance).toBe("1.2345");
+        expect(addr.tokenBalances).toEqual([]);
+    });
+
+    test("no test in this file performed a network request", () => {
+        expect(global.fetch).not.toHaveBeenCalled();
+    });
+});