The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
Low
PR
The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
Low
C
There is some impact on confidentiality, but the attacker either does not gain control of any data, or the information obtained does not have a significant impact on the system or its operations.
Integrity
Low
I
Modification of data is possible, but the attacker does not have control over what can be modified, or the extent of what the attacker can affect is limited. The data modified does not have a direct, serious impact on the system.
Availability
None
A
There is no impact on the availability of the system; the attacker does not have the ability to disrupt access to or use of the system.
Below is a copy: TP-Link TL-SG108E XSS / Weak Access Control
Overview
-------------
Three vulnerabilities have been discovered in the TP-Link TL-SG108E,
firmware 1.0.0 Build 20160722 Rel.50167:
CVE-2017-17745 - Cross Site Scripting (XSS) in system_name_set.cgi,
sysName parameter
CVE-2017-17746 - Weak access control for user authentication
CVE-2017-17747 - Weak access control for user logout
This is not an exhaustive list of vulnerabilities that may exist in
the device firmware.
Device Overview
-----------------------
>From http://www.tp-link.com.au/products/details/cat-41_TL-SG108E.html
- "The TL-SG108E 8-Port Gigabit Easy Smart switch is an ideal upgrade
from an unmanaged switch, designed for Small and Medium Business
networks that require simple network management. Network
administrators can effectively monitor traffic via Port Mirroring,
Loop Prevention and Cable Diagnostics features."
Affected Devices
-----------------------
Firmware Version: 1.0.0 Build 20160722 Rel.50167
Hardware Version: TL-SG108E 3.0
Older TL-SG108E devices may also be affected.
Disclosure Timeline
--------------------------
September 08th, 2017 - Vulnerabilities discovered after purchasing the device.
September 10th, 2017 - Contacted TP-Link via tp-link.com.au
September 12th, 2017 - TP-Link responded, requesting further information
September 12th, 2017 - Responded to TP-Link with vulnerability
specifics. Advised a 90 day disclosure timeline, with offer to
increase deadline if TP-Link wishes.
September 12th -> October 16th - Emails back and forth discussing how
to trigger the vulnerabilities.
October 16th, 2017 - TP-Link confirms XSS vulnerability
(CVE-2017-17745), advises an updated firmware will be released.
TP-Link advises two remaining vulnerabilities (CVE-2017-17746,
CVE-2017-17747) will not be fixed.
December 18th, 2017 - Applied to Mitre for CVE numbers.
December 19th, 2017 - Mitre assigned CVE-2017-17745, CVE-2017-17746,
CVE-2017-17747
December 19th, 2017 - Public disclosure.
As of this date (December 19th, 2017), no updated firmware has been
offered for testing, or released to the public.
Notes
--------
In all examples below, the TL-SG108E was configured with a LAN IP
address of 192.168.1.6.
Many thanks to Simon @ TP-Link for the prompt email responses.
CVE-2017-17745 - Stored Cross Site Scripting (XSS)
-------------------------------------------------------------------------
* Device is not validating input to the script system_name_set.cgi on
the TL-SG108E or on output to screen.
* Only the sysName variable in system_name_set.cgi was tested in this
instance. Other fields in the management web-application may have
similar problems, these were not tested.
Risks:
* In some network configurations (such as behind a NAT router, as
outlined in CVE-2017-17746) a malicious user could store XSS on the
TL-SG108E and cause the administrator of the TL-SG108E to execute
arbitrary javascript code in their browser.
Proof of Concept:
* Authenticate to the device in a browser
* Execute the following command from a terminal window: curl -vvvs -X
'GET' 'http://192.168.1.6/system_name_set.cgi?sysName=TL-SG"\]\};alert(1);</script>'
* To trigger the XSS: Browse -> System -> System Info. Alert box
containing '1' displays, indicating successful javascript execution.
Mitigation:
* Set the device password to a strong password.
* Restrict access to the device from approved administrator
workstations until an updated firmware is available.
CVE-2017-17746 - Weak access control
------------------------------------------------------
* All information regarding authenticated sessions is stored on the
TL-SG108E, no cookies are sent from the device to the client after
successful authentication.
Risks:
* Any other browser on a PC which has authenticated, is then also
treated as authenticated (Example: Login in Chrome, then open Firefox
and browse to the TL-SG108E, and the session is already authenticated)
* If the TL-SG108E is on the other side of a NAT router, ALL clients
behind the NAT are treated as authenticated.
Steps to reproduce:
* Authenticate from any PC.
* Any other browser on that system is then able to access the
web-interface without entering authentication information.
* By extension, guest VMs on that machine are then automatically authenticated.
Mitigation:
* Restrict access to the device from approved administrator
workstations until an updated firmware is available.
* Prevent any access to the web interface from devices behind a NAT router.
CVE-2017-17747 - Weak access control on Logout.htm
-------------------------------------------------------------------------
* Logout.htm can be called from any IP address, ending any
authenticated sessions on the device.
Risks:
* A denial of service condition can be triggered by calling the logout
script in a loop from any machine on the network regardless of their
authentication status, effectively making it impossible to access the
TL-SG108E management web-application.
Steps to reproduce:
* Authenticate from any PC.
* From another PC with a different IP address, access the logout page
(http://192.168.1.6/Logout.htm)
* The session on the first PC has been terminated.
Mitigation:
* Restrict access to the device from approved administrator
workstations until an updated firmware is available.
--
End disclosure.
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