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Reject JWT tokens with alg:none to prevent signature bypass #3

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Reject JWT tokens with alg:none to prevent signature bypass #3

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31 changes: 23 additions & 8 deletions lib/insecurity.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,19 @@ export const cutOffPoisonNullByte = (str: string) => {
return str
}

export const isAuthorized = () => expressJwt(({ secret: publicKey }) as any)
export const isAuthorized = () => {
const jwtMiddleware = expressJwt(({ secret: publicKey }) as any)
return (req: Request, res: Response, next: NextFunction) => {
const token = utils.jwtFrom(req)
if (token) {
const tokenHeader = jws.decode(token)
if (!tokenHeader?.header?.alg || (tokenHeader.header.alg as string).toLowerCase() === 'none') {
return res.status(401).json({ status: 'error', message: 'Unauthorized' })
}
}
jwtMiddleware(req, res, next)
}
}
export const denyAll = () => expressJwt({ secret: '' + Math.random() } as any)
export const authorize = (user = {}) => jwt.sign(user, privateKey, { expiresIn: '6h', algorithm: 'RS256' })
export const verify = (token: string) => token ? (jws.verify as ((token: string, secret: string) => boolean))(token, publicKey) : false
Expand Down Expand Up @@ -188,14 +200,17 @@ export const appendUserId = () => {
export const updateAuthenticatedUsers = () => (req: Request, res: Response, next: NextFunction) => {
const token = req.cookies.token || utils.jwtFrom(req)
if (token) {
jwt.verify(token, publicKey, (err: Error | null, decoded: any) => {
if (err === null) {
if (authenticatedUsers.get(token) === undefined) {
authenticatedUsers.put(token, decoded)
res.cookie('token', token)
const tokenHeader = jws.decode(token)
if (tokenHeader?.header?.alg && (tokenHeader.header.alg as string).toLowerCase() !== 'none') {
jwt.verify(token, publicKey, (err: Error | null, decoded: any) => {
if (err === null) {
if (authenticatedUsers.get(token) === undefined) {
authenticatedUsers.put(token, decoded)
res.cookie('token', token)
}
}
}
})
})
}
}
next()
}