Skip to content

fix(slack): validate webhook timestamps strictly #925

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
ralyodio merged 1 commit into from
Aug 3, 2026
Merged

fix(slack): validate webhook timestamps strictly #925

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
26 changes: 26 additions & 0 deletions packages/bots/slack/src/index.test.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -203,6 +203,32 @@ describe('Slack bot adapter', () => {
await closeable.close();
});

it('rejects non-decimal-integer Slack signature timestamps', async () => {
const { fetcher } = captureFetch();
let server: Server | undefined;
const closeable = await bot.register(
ctx(),
[],
{ port: 0, fetch: fetcher, onServerReady: (value) => { server = value; } },
);
const body = JSON.stringify({ type: 'event_callback', event: { type: 'message', channel: 'C123' } });
const now = Math.floor(Date.now() / 1000);
const invalidTimestamps = [
`${now}e0`,
`0x${now.toString(16)}`,
`${now}.5`,
` ${now} `,
`+${now}`,
];

for (const timestamp of invalidTimestamps) {
const response = await post(serverPort(server!), '/slack/events', body, signHeadersAt(body, timestamp));
expect(response.status).toBe(401);
expect(JSON.parse(response.body)).toEqual({ ok: false, error: 'invalid_signature' });
}
await closeable.close();
});

it('uses the default timestamp tolerance when config contains an invalid value', async () => {
const { fetcher } = captureFetch();
let server: Server | undefined;
Expand Down
3 changes: 2 additions & 1 deletion packages/bots/slack/src/index.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -420,8 +420,9 @@ function verifySlackSignature(
const timestamp = firstHeader(headers["x-slack-request-timestamp"]);
const signature = firstHeader(headers["x-slack-signature"]);
if (!timestamp || !signature) return false;
if (!/^\d+$/.test(timestamp)) return false;
const timestampNumber = Number(timestamp);
if (!Number.isFinite(timestampNumber)) return false;
if (!Number.isSafeInteger(timestampNumber)) return false;
if (
effectiveToleranceSeconds > 0
&& Math.abs(Math.floor(Date.now() / 1000) - timestampNumber) > effectiveToleranceSeconds
Expand Down
Loading