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oauth2: Resolves possible session fixation attack #770

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merged 1 commit into from
Feb 7, 2018
Merged

oauth2: Resolves possible session fixation attack #770

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48 changes: 25 additions & 23 deletions oauth2/consent_strategy.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,9 +15,8 @@
package oauth2

import (
"time"

"net/http"
"time"

"github.com/gorilla/sessions"
"github.com/ory/fosite"
Expand All @@ -39,18 +38,35 @@ type DefaultConsentStrategy struct {
ConsentManager ConsentRequestManager
}

func checkAntiReplayToken(consent *ConsentRequest, cookie *sessions.Session) error {
func (s *DefaultConsentStrategy) validateSession(req fosite.AuthorizeRequester, consent *ConsentRequest, cookie *sessions.Session) error {
if j, ok := cookie.Values[CookieCSRFKey]; !ok {
return errors.Errorf("Session cookie is missing anti-replay token")
return errors.Errorf("Session cookie is missing CSRF token")
} else if js, ok := j.(string); !ok {
return errors.Errorf("Session cookie anti-replay value is not a string")
return errors.Errorf("CSRF value in session cookie is not a string")
} else if js != consent.CSRF {
return errors.Errorf("Session cookie anti-replay value does not match value from consent response")
return errors.Errorf("CSRF value in session cookie does not match consent CSRF value")
} else if consent.CSRF != req.GetRequestForm().Get("consent_csrf") {
return errors.Errorf("CSRF value from query parameters does not match consent CSRF value")
}

if time.Now().After(consent.ExpiresAt) {
return errors.Errorf("Consent session expired")
}

if consent.ClientID != req.GetClient().GetID() {
return errors.Errorf("ClientID mismatch")
}

if consent.Subject == "" {
return errors.Errorf("Subject key is empty or undefined in consent response, check your payload.")
}

return nil
}

func (s *DefaultConsentStrategy) ValidateConsentRequest(req fosite.AuthorizeRequester, session string, cookie *sessions.Session) (claims *Session, err error) {
defer delete(cookie.Values, CookieCSRFKey)

consent, err := s.ConsentManager.GetConsentRequest(session)
if err != nil {
return nil, errors.WithStack(err)
Expand All @@ -67,21 +83,9 @@ func (s *DefaultConsentStrategy) ValidateConsentRequest(req fosite.AuthorizeRequ
}
}

if time.Now().After(consent.ExpiresAt) {
return nil, errors.Errorf("Token expired")
}

if consent.ClientID != req.GetClient().GetID() {
return nil, errors.Errorf("ClientID mismatch")
}

if consent.Subject == "" {
return nil, errors.Errorf("Subject key is empty or undefined in consent response, check your payload.")
}

if err := checkAntiReplayToken(consent, cookie); err != nil {
if err := s.validateSession(req, consent, cookie); err != nil {
if err := s.ConsentManager.RejectConsentRequest(session, &RejectConsentRequestPayload{
Reason: "Session cookie is missing anti-replay token",
Reason: "Unable to validate consent request",
}); err != nil {
return nil, err
}
Expand All @@ -92,8 +96,6 @@ func (s *DefaultConsentStrategy) ValidateConsentRequest(req fosite.AuthorizeRequ
req.GrantScope(scope)
}

delete(cookie.Values, CookieCSRFKey)

return &Session{
DefaultSession: &openid.DefaultSession{
Claims: &ejwt.IDTokenClaims{
Expand Down Expand Up @@ -126,7 +128,7 @@ func (s *DefaultConsentStrategy) CreateConsentRequest(req fosite.AuthorizeReques
RequestedScopes: req.GetRequestedScopes(),
ClientID: req.GetClient().GetID(),
ExpiresAt: time.Now().Add(s.DefaultChallengeLifespan),
RedirectURL: redirectURL + "&consent=" + id,
RedirectURL: redirectURL + "&consent=" + id + "&consent_csrf=" + csrf,
AccessTokenExtra: map[string]interface{}{},
IDTokenExtra: map[string]interface{}{},
}
Expand Down
40 changes: 31 additions & 9 deletions oauth2/consent_strategy_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ package oauth2

import (
"fmt"
"net/url"
"testing"
"time"

Expand Down Expand Up @@ -43,7 +44,15 @@ func TestConsentStrategy(t *testing.T) {
ExpiresAt: time.Now().Add(time.Hour),
}))
require.NoError(t, strategy.ConsentManager.PersistConsentRequest(&ConsentRequest{
ID: "granted_csrf",
ID: "granted_csrf_cookie",
Consent: ConsentRequestAccepted,
ClientID: "client_id",
Subject: "peter",
CSRF: "csrf_token",
ExpiresAt: time.Now().Add(time.Hour),
}))
require.NoError(t, strategy.ConsentManager.PersistConsentRequest(&ConsentRequest{
ID: "granted_csrf_request",
Consent: ConsentRequestAccepted,
ClientID: "client_id",
Subject: "peter",
Expand Down Expand Up @@ -71,36 +80,49 @@ func TestConsentStrategy(t *testing.T) {
d: "invalid session",
session: "not_granted",
expectErr: true,
cookie: &sessions.Session{Values: map[interface{}]interface{}{CookieCSRFKey: "csrf_token"}},
},
{
d: "session expired",
session: "granted_expired",
expectErr: true,
req: &fosite.AuthorizeRequest{Request: fosite.Request{Client: &fosite.DefaultClient{ID: "client_id"}}},
req: &fosite.AuthorizeRequest{Request: fosite.Request{Client: &fosite.DefaultClient{ID: "client_id"}, Form: url.Values{"consent_csrf": {"csrf_token"}}}},
cookie: &sessions.Session{Values: map[interface{}]interface{}{CookieCSRFKey: "csrf_token"}},
},
{
d: "granted",
session: "granted",
expectErr: false,
req: &fosite.AuthorizeRequest{Request: fosite.Request{Client: &fosite.DefaultClient{ID: "client_id"}}},
req: &fosite.AuthorizeRequest{Request: fosite.Request{Client: &fosite.DefaultClient{ID: "client_id"}, Form: url.Values{"consent_csrf": {"csrf_token"}}}},
cookie: &sessions.Session{Values: map[interface{}]interface{}{CookieCSRFKey: "csrf_token"}},
},
{
d: "client mismatch",
session: "granted",
expectErr: true,
req: &fosite.AuthorizeRequest{Request: fosite.Request{Client: &fosite.DefaultClient{ID: "mismatch_client"}}},
req: &fosite.AuthorizeRequest{Request: fosite.Request{Client: &fosite.DefaultClient{ID: "mismatch_client"}, Form: url.Values{"consent_csrf": {"csrf_token"}}}},
cookie: &sessions.Session{Values: map[interface{}]interface{}{CookieCSRFKey: "csrf_token"}},
},
{
d: "csrf detected",
session: "granted_csrf",
d: "consent request was not initiated by this user agent",
session: "granted_csrf_cookie",
expectErr: true,
req: &fosite.AuthorizeRequest{Request: fosite.Request{Client: &fosite.DefaultClient{ID: "client_id"}}},
cookie: &sessions.Session{Values: map[interface{}]interface{}{CookieCSRFKey: "invalid_csrf"}},
req: &fosite.AuthorizeRequest{Request: fosite.Request{Client: &fosite.DefaultClient{ID: "client_id"}, Form: url.Values{"consent_csrf": {"csrf_token"}}}},
cookie: &sessions.Session{Values: map[interface{}]interface{}{CookieCSRFKey: "very_different_csrf_token"}},
assert: func(t *testing.T, session *Session) {
cr, err := strategy.ConsentManager.GetConsentRequest("granted_csrf_cookie")
require.NoError(t, err)
assert.False(t, cr.IsConsentGranted())
},
},
{
d: "authorize url contains csrf token that does not match token set in consent request",
session: "granted_csrf_request",
expectErr: true,
req: &fosite.AuthorizeRequest{Request: fosite.Request{Client: &fosite.DefaultClient{ID: "client_id"}, Form: url.Values{"consent_csrf": {"very_different_csrf_token"}}}},
cookie: &sessions.Session{Values: map[interface{}]interface{}{CookieCSRFKey: "csrf_token"}},
assert: func(t *testing.T, session *Session) {
cr, err := strategy.ConsentManager.GetConsentRequest("granted_csrf")
cr, err := strategy.ConsentManager.GetConsentRequest("granted_csrf_request")
require.NoError(t, err)
assert.False(t, cr.IsConsentGranted())
},
Expand Down