Date: Tue, 13 Jan 2015 13:25:39 +0100
From: "kapejod@...glemail.com" <kapejod@...il.com>
To: SEC Consult Vulnerability Lab <research@...-consult.com>
Cc: fulldisclosure@...lists.org, bugtraq@...urityfocus.com
Subject: Re: [FD] SEC Consult SA-20150113-0 :: Multiple critical
 vulnerabilities in all snom desktop IP phones

Nice, it seems you had more luck with reporting those issues.

I reported the path traversal and null-byte injection to Snom on the 12th
of March 2013.


On Tue, Jan 13, 2015 at 10:53 AM, SEC Consult Vulnerability Lab <
research@...-consult.com> wrote:

> SEC Consult Vulnerability Lab Security Advisory < 20150113-0 >
> =======================================================================
>               title: Multiple critical vulnerabilities
>             product: snom IP phones
>  vulnerable version: all firmware versions <8.7.5.15, all firmware branches
>                      of all snom desktop IP phones (3xx, 7xx, 8xx, etc)
>                      are affected
>       fixed version: 8.7.5.15 (for all desktop phones)
>              impact: critical
>            homepage: http://www.snom.com
>               found: 2014-10-24
>                  by: Johannes Greil, Stefan Viehböck
>                      SEC Consult Vulnerability Lab
>                      https://www.sec-consult.com
> =======================================================================
>
> Vendor description:
> ===================
>
> "snom technology AG develops and manufacturers Voice-over-IP (VoIP)
> telephones
> based on open standard for enterprise communications.
> [...]
> The devices are suitable for use in all business environments ranging from
> home offices to small- and medium-sized enterprises and large corporations.
> snom also works directly with carriers, Internet Service Providers, and OEM
> customers. The company is globally present through branch offices and a
> partner network."
>
> source: http://www.snom.com/en/company/about-snom/
>
>
> "snom phones (hardware and software) are developed in Germany and strictly
> adhere to all applicable security standards (TLS and SRTP). In contrast to
> many of our competitors, snom as a German manufacturer is required to
> abide by
> the strict German data protection regulations and laws. This is of
> considerable importance for the prevention of phone-tapping."
>
> source: http://www.snom.com/en/company/statement/security/
>
>
> Business recommendation:
> ========================
> A short security crash test resulted in multiple critical security
> vulnerabilities within all desktop IP phones of snom and all firmware
> versions.
>
> There exist highly critical attack vectors as the IP phones can be
> completely
> compromised (root) by an external attacker. It is possible to e.g.
>
> * add a backdoor to the system which will even survive a factory reset!
> * remotely activate the built-in microphone in order to surveil the room
> where
>   the phone is located,
> * tap into phone calls made or received by the compromised phone (e.g. by
>   installing a sniffer on the phone),
> * redirect phone numbers to premium rate numbers which may result in high
>   costs,
> * use the phone as a jump-host into the internal network and attack other
>   systems.
>
> It is highly recommended by SEC Consult not to use this product until a
> thorough security review of the firmware has been performed by security
> professionals and all identified issues have been resolved.
>
>
> Vulnerability overview/description:
> ===================================
> 1) Multiple cross site scripting vulnerabilities
> ------------------------------------------------
> The device's web interface suffers from multiple reflected & stored cross
> site
> scripting vulnerabilities, which may allow an attacker to gain unauthorized
> access to the admin interface and further compromise the phone.
>
>
> 2) Path traversal filter bypass
> -------------------------------
> The firmware has a rudimentary filter against path traversal attacks within
> URL parameters. E.g. "../" characters within a parameter value will be
> filtered. This can be easily bypassed and potentially exploited for further
> attacks on the system (e.g. XML minibrowser or action URL features).
>
>
> 3) Directory traversal & privilege escalation
> ---------------------------------------------
> It is possible to directly access the file system via path/directory
> traversal
> attacks within the URL. In order to exploit it, a certain file extension
> has
> to be added and cut off via a null byte which must not be transmitted in
> URL
> encoded form.
>
> Attackers are then able to easily gain access to sensitive files such as
> the
> snom phone configuration file which includes all passwords in cleartext,
> even
> for the admin user account (admin mode) which should not be accessible to a
> low privileged user.
>
>
> 4) Command execution via VPN profiles
> -------------------------------------
> The phone's firmware supports OpenVPN profiles and the configuration can be
> uploaded via a tarball from a remote webserver. Admin access in the web
> GUI is
> needed which can be gained by exploiting other vulnerabilities, such as 3)
> and
> 5).
> By combining more identified vulnerabilities, even a remote attacker would
> be
> able to compromise the internal phone, e.g. add a XSS payload via CSRF in
> order to gain access to the admin mode password, then install the malicious
> OpenVPN profile.
>
> The attacker can prepare a malicious OpenVPN configuration file with shell
> commands in order to execute arbitrary commands on the IP phone with
> highest
> access rights on the operating system (root).
>
> There exist highly critical attack vectors after gaining root access to the
> phone:
> * add a backdoor to the system which will even survive a factory reset!
> * remotely activate the built-in microphone in order to surveil the room
> where
>   the phone is located,
> * tap into phone calls made or received by the compromised phone,
> * use the phone as a jump-host into the internal network and attack other
>   systems,
> * etc.
>
> This can also be exploited via TR069 or auto provisioning by a
> man-in-the-middle
> attacker! This can be achieved via the attacks described in 8).
>
>
> 5) Authentication bypass & privilege escalation
> -----------------------------------------------
> Unprivileged users (non-admin accounts) have the ability to change the
> settings for functions keys or action URLs on the phone. Attackers are
> able to
> exploit those features in order to gain administrative access rights on the
> web GUI and then exploit further vulnerabilities again, e.g. 4).
>
> The webserver does not check for any user credentials when accessed via
> localhost. By reconfiguring a function key or action URL to submit a
> request
> to localhost, it is possible to alter any configuration setting, e.g.
> overwrite the current admin-mode password and therefore gain admin access
> rights!
>
> This vulnerability is also automatically exploitable via CSRF, local
> access to
> the phone (e.g. for pressing a function key) is _not_ required!
>
> Further short tests have shown, that an attacker could also use the request
> for altering the settings by directly accessing the IP address over the
> network. The bypass via localhost was not necessary. This can be achieved
> by
> sending the same malicious request multiple times.
>
>
> 6) Cross-site request forgery issues
> ------------------------------------
> Attackers are able to remotely change settings, e.g. the admin mode
> password,
> on the device via CSRF attacks. Furthermore, it is possible to initiate
> arbitrary phone calls, e.g. to premium rate numbers, via CSRF!
>
> Short tests have shown that the anti-CSRF feature "use_hidden_tags" was not
> effective in the tested firmware version.
>
>
> 7) Remote firmware update by unprivileged users
> -----------------------------------------------
> Unprivileged users are able to perform a firmware update via the web GUI.
> This is also exploitable for a remote attacker using CSRF! A local attacker
> could otherwise just simply boot the phone.
> An attacker would potentially be able to downgrade to a certain older
> firmware, in order to make older security bugs for exploitation available
> again. The phone presents the unprivileged user an error message, that
> admin
> access is required. But the phone will automatically perform the firmware
> update anyways!
>
>
> 8) Plaintext provisioning through snom servers & weak device identifier
> -----------------------------------------------------------------------
> Every IP phone contacts the provisioning server of snom at
> "provisioning.snom.com" (IP: 80.237.155.31) for an initial setup phase or
> after a factory reset in order to retrieve the auto-provisioning URL for
> the
> TR069 server of the ISP. This connection is not secured and uses plaintext
> HTTP communication.
>
> Man-in-the-middle attackers (e.g. TAO/QUANTUM attacks, DNS or BGP
> hijacking,
> etc.) can manipulate those requests, use their own TR069 server and
> install a
> backdoor on the phone (e.g. see 4) and afterwards provide the real TR069
> URL
> for the ISP. The backdoor will survive the new settings/resets or firmware
> updates and be available to the attacker.
>
>
> Furthermore, the phone identifies itself only via the last three bytes of
> the
> MAC address, which can easily be brute-forced. An attacker would be able to
> retrieve all TR069 URLs of the ISPs and he could then potentially further
> attack those systems.
>
>
>
> Proof of concept:
> =================
> Detailed proof of concept information has been removed from this advisory.
> This section will hence only give an overview regarding the
> vulnerabilities.
>
> 1) Multiple cross site scripting vulnerabilities
> ------------------------------------------------
> The following payload can be used within the [removed] parameter in order
> to permanently store JavaScript within [removed]. This is also possible by
> importing [removed] contents via CSV files:
>    [payload removed]
>
> The following URL automatically adds a new entry to the phonebook which
> contains JS code. This is also exploitable via CSRF to automatically insert
> malicious code without user interaction:
> [URL removed]
>
>
> The following URL is also exploitable because the webserver does not
> filter error messages. Browsers that do not url-encode the input are
> affected
> (e.g. older IE versions such as v6):
> [URL removed]
>
>
>
> 2) Path traversal filter bypass
> -------------------------------
> In order to bypass the "../" filter, the following can be used as an
> example:
> [payload removed]
>
> The string [removed] at the end is necessary, otherwise the basename will
> be
> duplicated by the system.
>
>
> 3) Directory traversal & privilege escalation
> ---------------------------------------------
> The following URL can be used to gain access to the file /etc/passwd by
> combining a real null byte (not URL encoded %00), e.g. by using burp proxy
> hex
> mode, with certain appended file extensions:
> [URL removed]
>
> The following URL allows an attacker access to SIP credentials, admin mode
> password and other configuration settings in plaintext of the snom
> config.xml
> file:
> [URL removed]
>
>
>
> 4) Command execution via VPN profiles
> -------------------------------------
> The following OpenVPN profile can be used in order to open a reverse shell
> to
> the attacker's system. The attacker will gain the highest access rights on
> the
> phone (root):
>     dev tun
>     proto tcp
>     script-security 2
>     remote $someArbitraryOpenVPNIP 443
>     cipher AES-128-CBC
>     auth SHA1
>     tls-verify [payload removed]
>     resolv-retry infinite
>     nobind
>     persist-key
>     persist-tun
>     client
>     verb 3
>     [...]
>
> In order to exploit it, any publicly available OpenVPN server can be
> misused
> with any credentials, as the payload is already executed during the initial
> TLS setup phase.
>
> It is easily possible to install a backdoor on the phone because the flash
> storage is writable. SEC Consult tested this by altering the init script
> "[removed]" and added a SSH daemon (as an example, any command can be
> run) which will be started on each boot. The init script does not get
> overwritten even after a factory reset, hence the backdoor can still be
> accessed afterwards.
>
>
> Attackers with root access can now completely compromise the phone, e.g.
> alter
> the configuration in order to enable call redirection to premium rate
> numbers,
> access the microphone, install a sniffer in order to record
> incoming/outgoing
> phone calls, or attack other internal systems, etc.
>
>
> 5) Authentication bypass & privilege escalation
> -----------------------------------------------
> By using the following URL to localhost as a so-called "action URL"
> associated
> to a function key on the device, it is possible to gain administrative
> access
> rights because the admin-mode password will be set to an
> attacker-controlled
> value:
>
> [URL removed]
>
> This also works when "restrict_uri_queries" and "use_hidden_tags" are set
> to
> "on", sometimes the function key has to be pressed multiple times then.
>
> See vulnerability 6) for infos on how to "press" the function key remotely
> via
> CSRF.
>
> By requesting the following URL with the direct IP address (not localhost)
> repeatedly, it was also possible to gain access to admin mode:
>
> [URL removed]
>
>
> 6) Cross-site request forgery issues
> ------------------------------------
> The following URL can be used for CSRF attacks in order to initiate phone
> calls to arbitrary numbers (e.g. premium rate):
> [URL removed]
>
>
> The following URL will change the function key setting in order to change
> the
> admin mode password (see 5) via CSRF:
>
> a) URL for setting the function key value:
> [URL removed]
>
> b) URL for saving the function key modifications:
> [URL removed]
>
> c) URL for automatically executing the command of the function key "P1":
> [URL removed]
>
>
> By exploiting other issues in combination with CSRF, such as XSS and the
> OpenVPN command execution flaw, it is possible to remotely compromise the
> phone via CSRF.
>
>
> 7) Remote firmware update by unprivileged users
> -----------------------------------------------
> The following URL can be used in order to load another firmware onto the
> device. The device will immediately switch to the firmware download mode
> even
> when accessed as unprivileged user, although the phone prints an error
> message
> that admin-mode access is required:
>
> [URL removed]
>
>
> 8) Plaintext provisioning through snom servers & weak device identifier
> -----------------------------------------------------------------------
> No proof of concept necessary, wireshark shows plaintext communication.
>
>
> Vulnerable / tested versions:
> =============================
> The IP phone snom 710 has been tested during a short security evaluation
> crash
> test with firmware version 8.7.4.7a pre-installed.
>
> Snom confirmed that _all_ older firmware versions are affected by the
> documented
> security vulnerabilities except the current new release 8.7.5.15!
>
> Although snom IP phone 710 has been tested, also _all_ other snom desktop
> IP phone
> products (e.g. 3xx, 7xx, 8xx, etc) are affected!
>
>
> Vendor contact timeline:
> ========================
> 2014-10-31: Contacting vendor through office@...m.com, requesting security
>             contact, attaching responsible disclosure policy & encryption
> keys
> 2014-11-04: No answer, contacting support@...m.com, sales@...m.com &
>             marketing@...m.com, attaching responsible disclosure policy &
>             encryption keys
> 2014-11-06: Calling German office, trying to reach a security contact, no
>             useful information received
>             Contacting other direct contacts of snom via Sales
> 2014-11-07: Receiving contact for security communication via Sales,
> exchanging
>             encryption keys and sending encrypted security advisory to
> given
>             contact
> 2014-11-18: Requesting status update - vulnerabilities have been forwarded
> to
>             developers and are being processed
> 2014-11-28: Telco with new technical snom contact
> 2014-12-08 - 2014-12-11: Answering questions of snom regarding some
>             vulnerabilities, postponing advisory release deadline to 13th
>             January 2015, more time needed
> 2014-12-30: Requesting status update
> 2015-01-05: Last fixes are already in progress, scheduled for 13th January,
>             receiving document containing detailed information regarding
> the
>             fixes
> 2015-01-07: Asking which firmware versions and products are affected
> 2015-01-08: Calling snom, verifying affected products
> 2015-01-08: Sending adjusted advisory to snom
> 2015-01-08: Informing CERT.at and CERT-Bund Germany (BSI) about pending
> release
> 2015-01-13: Coordinated release of security advisory
>
>
>
> Solution:
> =========
> The vendor provides a new firmware version v8.7.5.15 and urges all users to
> _immediately_ upgrade to this version!
>
> Vendor security note & firmware download:
> http://wiki.snom.com/8.7.5.15_OpenVPN_Security_Update
>
> Older firmware branches will not be patched and the upgrade to this new
> version is therefore absolutely necessary for all users!
>
>
> According to the vendor, the OpenVPN binary will be removed from the
> firmware
> per default and can be loaded as a small firmware update afterwards if
> necessary (see vendor security note above). Users of the OpenVPN feature
> will
> get a warning as they will be affected by the identified vulnerability
> again
> after enabling the feature.
>
>
> Workaround:
> ===========
> No workaround available. The vendor urges all customers to immediately
> upgrade
> the firmware of all snom IP phones.
>
>
> Advisory URL:
> =============
> https://www.sec-consult.com/en/Vulnerability-Lab/Advisories.htm
>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> SEC Consult Vulnerability Lab
>
> SEC Consult
> Vienna - Bangkok - Frankfurt/Main - Montreal - Singapore - Vilnius - Zurich
>
> Headquarter:
> Mooslackengasse 17, 1190 Vienna, Austria
> Phone:   +43 1 8903043 0
> Fax:     +43 1 8903043 15
>
> Mail: research at sec-consult dot com
> Web: https://www.sec-consult.com
> Blog: http://blog.sec-consult.com
> Twitter: https://twitter.com/sec_consult
>
> Interested to work with the experts of SEC Consult?
> Write to career@...-consult.com
>
> EOF J. Greil / @2015
>
>
>
> _______________________________________________
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> http://nmap.org/mailman/listinfo/fulldisclosure
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