X41 D-Sec GmbH Security Advisory: X41-2017-005

Multiple Vulnerabilities in peplink balance routers
===================================================

Overview
--------
Confirmed Affected Versions: 7.0.0-build1904
Confirmed Patched Versions:
fw-b305hw2_380hw6_580hw2_710hw3_1350hw2_2500-7.0.1-build2093.bin
Vulnerable Firmware:
fw-b305hw2_380hw6_580hw2_710hw3_1350hw2_2500-7.0.0-build1904.bin
Models: Balance Routers 305, 380, 580, 710, 1350, 2500
Vendor: Peplink
Vendor URL: https://www.peplink.com/
Vector: Network
Credit: X41 D-Sec GmbH, Eric Sesterhenn
Additional Credits: Claus Overbeck (Abovo IT)
Status: Public
Advisory-URL: https://www.x41-dsec.de/lab/advisories/x41-2017-005-peplink/


Summary and Impact
------------------
Several issues have been identified, which allow attackers to access the
administrative web interface with admin credentials, delete files,
perform CSRF and XSS attacks.


Product Description
-------------------
From the vendor webpage:
Use Load Balancing and SpeedFusion bandwidth bonding to deliver
superfast VoIP, video streaming, and data using an SD-WAN enabled
network. Even with a basic Balance 20 dual-WAN router, you can mix
different transport technologies and providers to keep your network up
when individual links go down. Switching between links is automatic and
seamless.



SQL Injection via bauth Cookie
==============================
Severity Rating: Critical
Vector: Network
CVE: CVE-2017-8835
CWE: 89
CVSS Score: 9.8
CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Summary and Impact
------------------
Peplink devices are vulnerable to an SQL injection attack via the bauth
cookie parameter which is set e.g. when accessing
https://ip/cgi-bin/MANGA/admin.cgi.

The injection can be checked with the following command:

./sqlmap.py -u "https://ip/cgi-bin/MANGA/admin.cgi"
--cookie="bauth=csOWLxU4BvoMfhY2rHLVFm1EmZWV74zinla9IVclqrYxH16426647"
-p"bauth" --level 5 --risk 3 --dbms sqlite --technique=BEUSQ
--flush-session -t trace.log --prefix "'" --suffix "--" -a

The vulnerability in the Peplink device allows to access the SQLite
session database containing user and session variables. By using the the
following cookie in a web request, it is possible to select a running
administrator session to be used for the attackers login.

bauth=-12' or id IN (select s.id from sessions as s left join
sessionsvariables as v on v.id=s.id where v.name='rwa' and v.value='1')
or '1'='2

By forming specialised SQL queries, it is possible to retrieve usernames
from the database. This worked by returning a valid session in case the
username existed and no session if it did not exist. In the first case
the server did not set a new session cookie in the response to the request.

SELECT id FROM sessions WHERE sessionid = '-14' or id IN (select s.id
from sessions as s left join sessionsvariables as v on v.id=s.id where
v.name='username' and substr(v.value,1,3)='adm')



Workarounds
-----------
Install vendor supplied update.


No CSRF Protection
==================
Severity Rating: Medium
Vector: Network
CVE: CVE-2017-8836
CWE: 352
CVSS Score: 5.4
CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Summary and Impact
------------------
The CGI scripts in the administrative interface are not protected
against cross site request forgery attacks. This allows an attacker to
execute commands, if a logged in user visits a malicious website. This
can for example be used to change the credentials of the administrative
webinterface.


Workarounds
-----------
Install vendor supplied update.




Passwords stored in Cleartext
=============================
Severity Rating: Medium
Vector: Network
CVE: CVE-2017-8837
CWE: 256
CVSS Score: 4.0
CVSS Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Summary and Impact
------------------
The Peplink devices store passwords in cleartext in the files
/etc/waipass and /etc/roapass. In case one of these devices is
compromised the attacker can gain access to the cleartext passwords and
abuse them to compromise further systems.


Workarounds
-----------
Install vendor supplied update.




XSS via syncid Parameter
========================
Severity Rating: Medium
Vector: Network
CVE: CVE-2017-8838
CWE: 80
CVSS Score: 5.4
CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Summary and Impact
------------------
If the webinterface is accessible, it is possible to abuse the syncid
parameter to trigger a cross-site-scripting issue by calling
https://ip/cgi-bin/HASync/hasync.cgi?debug=1&syncid=123%3Cscript%3Ealert%281%29%3C/script%3E

This executes the JavaScript in the victims browser, which can be abused
to steal session cookies.

Workarounds
-----------
Install vendor supplied update.




XSS via preview.cgi
===================
Severity Rating: Medium
Vector: Network
CVE: CVE-2017-8839
CWE: 80
CVSS Score: 5.4
CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Summary and Impact
------------------
If the webinterface is accessible, it is possible to abuse the the
orig_url parameter to trigger a cross-site-scripting issue in
/guest/preview.cgi. The injection is directly into existing JavaScript.

This executes the JavaScript in the victims browser, which can be abused
to steal session cookies.

Workarounds
-----------
Install vendor supplied update.



File Deletion
=============
Severity Rating: Medium
Vector: Network
CVE: CVE-2017-8841
CWE: 73
CVSS Score: 6.5
CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:H/A:H

Summary and Impact
------------------
A logged in user can delete arbitrary files on the Peplink devices, by
abusing the /cgi-bin/MANGA/firmware_process.cgi. When an absolute path
is provided to the upfile.path parameter the file provided in the path
is deleted during the process. This can be abused to cause a denial of
service (DoS). In combination with the missing CSRF protection, this can
be abused remotely via a logged in user.

Workarounds
-----------
Install vendor supplied update.




Information Disclosure
======================
Severity Rating: Medium
Vector: Network
CVE: CVE-2017-8840
CWE: 200
CVSS Score: 5.3
CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Summary and Impact
------------------
If the webinterface is accessible, it is possible to retrieve sensitive
information without a valid login by opening
cgi-bin/HASync/hasync.cgi?debug=1

This displays the following:

-----8<------------------------------------------------
Master LAN Address    = [ <internal ip> / <netmask> ]
Serial Number         = [ <serial number> ]
HA Group ID           = [ <group id> ]
Virtual IP            = [ <internal ip> / <netmask> ]
Submitted syncid      = [ <syncid> ]
-----8<------------------------------------------------

This information can be valuable for an attacker to exploit other issues.

Workarounds
-----------
Install vendor supplied update.




About X41 D-Sec GmbH
--------------------
X41 D-Sec is a provider of application security services. We focus on
application code reviews, design review and security testing. X41 D-Sec
GmbH was founded in 2015 by Markus Vervier. We support customers in
various industries such as finance, software development and public
institutions.

Timeline
--------
2017-04-07	Issue found
2017-04-10	Vendor asked for security contact
2017-04-11	Vendor replied, send GPG key
2017-04-11	Information supplied to vendor
2017-04-11	Vendor acknowledges that the information is received
2017-04-17	Vendor acknowledges SQL injection
2017-05-08	CVE IDs for all issues requested
2017-05-08	CVE IDs assigned
2017-05-11	Vendor informed about CVE IDs
2017-05-29	Version provided to X41 for testing
2017-05-31	First test results send back to the vendor
2017-06-01	Remaining test results send back to the vendor
2017-06-05	Coordinated Firmware and Advisory release