mirrors/EWF
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Now JWT_LOADER takes the alg as argument, to avoid security issue where the lib is taking alg from the header (which may be a bad security weakness).

Browse Source
This commit is contained in:
Jocelyn Fiat
2017-07-11 23:32:11 +02:00
parent 27ee20f99b
commit 2748e1d9ee
4 changed files with 105 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

31
library/security/jwt/src/jwt_loader.e
View File

@@ -1,8 +1,8 @@
note
description: "Summary description for {JWT_LOADER}."
author: ""
description: "Loader and verifier to JWT token."
date: "$Date$"
revision: "$Revision$"
EIS: "name=Known Critical vulnerabilities in JWT libs", "protocol=URI", "src=https://auth0.com/blog/critical-vulnerabilities-in-json-web-token-libraries/"
class
JWT_LOADER
@@ -12,9 +12,13 @@ inherit
feature -- Access
token (a_token_input: READABLE_STRING_8; a_secret: READABLE_STRING_8; ctx: detachable JWT_CONTEXT): detachable JWT
-- Decoded token from `a_token_input` given the secret `a_secret`, and optional context `ctx`
token (a_token_input: READABLE_STRING_8; a_alg: detachable READABLE_STRING_8; a_verification_key: READABLE_STRING_8; ctx: detachable JWT_CONTEXT): detachable JWT
-- Decoded token from `a_token_input` given the verification key `a_verification_key` and optional (but recommended) signature algorithm `a_alg`, and optional context `ctx`
-- used to specify eventual issuer and various parameters.
-- WARNING: passing Void for `a_alg` is not safe, as the server should know which alg he used for tokens,
-- leaving the possibility to use the header alg is dangerous as client may use "none" and then bypass verification!
require
a_valid_alg: a_alg /= Void implies is_supporting_signature_algorithm (a_alg)
local
jws: JWS
i,j,n: INTEGER
@@ -29,20 +33,27 @@ feature -- Access
l_enc_payload := a_token_input.substring (i + 1, j - 1)
l_signature := a_token_input.substring (j + 1, n)
create jws.make_with_json_payload (base64url_decode (l_enc_payload))
alg := signature_algorithm_from_encoded_header (l_enc_header)
jws.set_algorithm (alg)
if alg = Void then
-- Use default
alg := alg_hs256
if a_alg /= Void then
if alg /= Void and then not alg.is_case_insensitive_equal_general (a_alg) then
jws.report_mismatched_alg_error (a_alg, alg)
else
alg := a_alg
end
else
if alg = Void then
-- Use default
alg := alg_hs256
end
end
jws.set_algorithm (alg)
check alg_set: alg /= Void end
if ctx = Void or else not ctx.validation_ignored then
if not is_supporting_signature_algorithm (alg) then
jws.report_unsupported_alg_error (alg)
alg := alg_hs256
end
if not l_signature.same_string (signature (l_enc_header, l_enc_payload, a_secret, alg)) then
if not l_signature.same_string (signature (l_enc_header, l_enc_payload, a_verification_key, alg)) then
jws.report_unverified_token_error
end
if