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AUSCERT External Security Bulletin Redistribution
ESB-2020.3276
Cisco IOS XE Software IOx vulnerabilities
25 September 2020
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS XE Software
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Root Compromise -- Existing Account
Resolution: Patch/Upgrade
CVE Names: CVE-2020-3396 CVE-2020-3393
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxe-iox-app-host-mcZcnsBt
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iox-usb-guestshell-WmevScDj
Comment: This bulletin contains two (2) Cisco Systems security advisories.
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco IOS XE Software IOx Application Hosting Privilege Escalation
Vulnerability
Priority: Medium
Advisory ID: cisco-sa-iosxe-iox-app-host-mcZcnsBt
First Published: 2020 September 24 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvr56862CSCvr69240
CVE-2020-3393
CWE-269
Summary
o A vulnerability in the application-hosting subsystem of Cisco IOS XE
Software could allow an authenticated, local attacker to elevate privileges
to root on an affected device. The attacker could execute IOS XE commands
outside the application-hosting subsystem Docker container as well as on
the underlying Linux operating system. These commands could be run as the
root user.
The vulnerability is due to a combination of two factors: (a) incomplete
input validation of the user payload of CLI commands, and (b) improper
role-based access control (RBAC) when commands are issued at the command
line within the application-hosting subsystem. An attacker could exploit
this vulnerability by using a CLI command with crafted user input. A
successful exploit could allow the lower-privileged attacker to execute
arbitrary CLI commands with root privileges. The attacker would need valid
user credentials to exploit this vulnerability.
Cisco has released software updates that address this vulnerability. There
are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-iosxe-iox-app-host-mcZcnsBt
Affected Products
o Vulnerable Products
At the time of publication, this vulnerability affected Cisco IOS XE
Software releases 16.12.1 and later with the Application Hosting feature
enabled and the hosted application running.
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Determine the Device Configuration
To determine whether the Application Hosting feature is enabled, assess the
following conditions:
Use the show running-config | include app-hosting appid command to
determine whether app-hosting has been configured:
Router# show running-config | include app-hosting appid
app-hosting appid MYAPP
Use the show app-hosting list command to determine whether the application
referenced in the output of the preceding command is running:
Router# show app-hosting list
App id State
---------------------------------------------------------
MYAPP RUNNING
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following
Cisco software:
IOS Software
IOS XR Software
NX-OS Software
Wireless LAN Controller Software
Details
o The Cisco Application Hosting feature extends the cloud to the edge of the
network, enabling distributed data processing closer to the source.
Application hosting on the switch provides efficient access to live network
traffic and the rich telemetry supported by the infrastructure. This access
enables administrators to host security, network monitoring/
troubleshooting, and analytics tools without requiring expensive compute
nodes. Application hosting also shortens the development cycle by allowing
administrators to run off-the-shelf Docker apps.
For additional information, see What is Application Hosting
Workarounds
o There are no workarounds that address this vulnerability. To mitigate this
vulnerability if application hosting is not needed, administrators can
disable the Application Hosting feature or remove the configuration for the
hosted applications.
Fixed Software
o When considering software upgrades , customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories page , to determine exposure and a complete
upgrade solution.
In all cases, customers should ensure that the devices to be upgraded
contain sufficient memory and confirm that current hardware and software
configurations will continue to be supported properly by the new release.
If the information is not clear, customers are advised to contact the Cisco
Technical Assistance Center (TAC) or their contracted maintenance
providers.
Cisco IOS and IOS XE Software
To help customers determine their exposure to vulnerabilities in Cisco IOS
and IOS XE Software, Cisco provides the Cisco Software Checker to identify
any Cisco Security Advisories that impact a specific software release and
the earliest release that fixes the vulnerabilities described in each
advisory ("First Fixed"). If applicable, the tool also returns the earliest
release that fixes all the vulnerabilities described in all the advisories
identified ("Combined First Fixed").
Customers can use the Cisco Software Checker to search advisories in the
following ways:
Choose the software and one or more releases
Upload a .txt file that includes a list of specific releases
Enter the output of the show version command
After initiating a search, customers can customize the search to include
all Cisco Security Advisories, a specific advisory, or all advisories in
the most recent bundled publication.
Customers can also use the following form to determine whether a release is
affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
Software release-for example, 15.1(4)M2 or 3.13.8S :
[ ] [Check]
By default, the Cisco Software Checker includes results only for
vulnerabilities that have a Critical or High Security Impact Rating (SIR).
To include results for Medium SIR vulnerabilities, customers can use the
Cisco Software Checker on Cisco.com and check the Medium check box in the
drop-down list under Impact Rating when customizing a search.
For a mapping of Cisco IOS XE Software releases to Cisco IOS Software
releases, refer to the Cisco IOS XE 2 Release Notes , Cisco IOS XE 3S
Release Notes , or Cisco IOS XE 3SG Release Notes , depending on the Cisco
IOS XE Software release.
Exploitation and Public Announcements
o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
any public announcements or malicious use of the vulnerability that is
described in this advisory.
Source
o This vulnerability was found by Victor Kamensky of Cisco during internal
security testing.
Cisco Security Vulnerability Policy
o To learn about Cisco security vulnerability disclosure policies and
publications, see the Security Vulnerability Policy . This document also
contains instructions for obtaining fixed software and receiving security
vulnerability information from Cisco.
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-iosxe-iox-app-host-mcZcnsBt
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-SEP-24 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------------------------------------------------------------
Cisco IOS XE Software IOx Guest Shell USB SSD Namespace Protection Privilege
Escalation Vulnerability
Priority: Medium
Advisory ID: cisco-sa-iox-usb-guestshell-WmevScDj
First Published: 2020 September 24 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvr50406
CVE-2020-3396
CWE-284
Summary
o A vulnerability in the file system on the pluggable USB 3.0 Solid State
Drive (SSD) for Cisco IOS XE Software could allow an authenticated,
physical attacker to remove the USB 3.0 SSD and modify sensitive areas of
the file system, including the namespace container protections.
The vulnerability occurs because the USB 3.0 SSD control data is not stored
on the internal boot flash. An attacker could exploit this vulnerability by
removing the USB 3.0 SSD, modifying or deleting files on the USB 3.0 SSD by
using another device, and then reinserting the USB 3.0 SSD on the original
device. A successful exploit could allow the attacker to remove container
protections and perform file actions outside the namespace of the container
with root privileges.
Cisco has released software updates that address this vulnerability. There
are no workarounds that address this vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-iox-usb-guestshell-WmevScDj
Affected Products
o Vulnerable Products
At the time of publication, this vulnerability affected Cisco Catalyst 9300
Series Switches and Cisco Catalyst 9500 Series Switches if they were
running a vulnerable release of Cisco IOS XE Software with the IOx Guest
Shell enabled and a USB 3.0 SSD installed.
For information about which Cisco software releases are vulnerable, see the
Fixed Software section of this advisory.
Determine the Device Configuration
To determine whether the device has a vulnerable configuration, assess the
IOx Guest Shell and USB 3.0 SSD status.
Determine Whether the IOx Guest Shell Is Enabled
To determine whether the IOx Guest Shell is enabled, use the show
app-hosting list privileged command. The following command output shows a
device with the IOx Guest Shell enabled:
Device# show app-hosting list
App id State
------------------------------------------------------
guestshell RUNNING
Determine Whether a USB 3.0 SSD Drive Is Installed
To determine whether a USB 3.0 SSD pluggable drive is installed, use the
show inventory | include usbflash* CLI command. If output is returned, the
drive is installed.
9300# show inventory | include usbflash*
NAME: "usbflash1", DESCR: "usbflash1" PID: SSD-120G , VID: STP21460FN9, SN: V01
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Cisco has confirmed that this vulnerability does not affect the following
Cisco products:
IOS Software
IOS XR Software
NX-OS Software
Details
o The Cisco Catalyst 9300 and 9500 Series Switches have a USB 3.0 SSD port on
the rear panel of the switch. This port supports an optional 120GB USB 3.0
SSD storage device (SSD-120G). SSD-120G provides an extra 120GB of storage
for application hosting. Applications can be hosted in Kernel-based Virtual
Machines (KVMs), Linux Containers (LXCs), or Docker containers. SSD-120G
can also be used to save packet captures, trace logs generated by the
operating system, Graceful Insertion and Removal (GIR) snapshots, and
third-party applications. SSD-120G can be used simultaneously as a
general-purpose storage device and as an application-hosting device.
Administrators must use only Cisco USB drives; non-Cisco USB drives are not
supported. SSD-120G is enabled with Self-Monitoring, Analysis and Reporting
Technology (S.M.A.R.T.) functionality to monitor endurance, predict wear
out, and perform various self-tests.
For additional information, see USB 3.0 SSD Overview in the Cisco Catalyst
9300 Series Switches Hardware Installation Guide .
Workarounds
o There are no workarounds that address this vulnerability.
Fixed Software
o When considering software upgrades , customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories page , to determine exposure and a complete
upgrade solution.
In all cases, customers should ensure that the devices to be upgraded
contain sufficient memory and confirm that current hardware and software
configurations will continue to be supported properly by the new release.
If the information is not clear, customers are advised to contact the Cisco
Technical Assistance Center (TAC) or their contracted maintenance
providers.
Cisco IOS and IOS XE Software
To help customers determine their exposure to vulnerabilities in Cisco IOS
and IOS XE Software, Cisco provides the Cisco Software Checker to identify
any Cisco Security Advisories that impact a specific software release and
the earliest release that fixes the vulnerabilities described in each
advisory ("First Fixed"). If applicable, the tool also returns the earliest
release that fixes all the vulnerabilities described in all the advisories
identified ("Combined First Fixed").
Customers can use the Cisco Software Checker to search advisories in the
following ways:
Choose the software and one or more releases
Upload a .txt file that includes a list of specific releases
Enter the output of the show version command
After initiating a search, customers can customize the search to include
all Cisco Security Advisories, a specific advisory, or all advisories in
the most recent bundled publication.
Customers can also use the following form to determine whether a release is
affected by any Cisco Security Advisory by entering a Cisco IOS or IOS XE
Software release-for example, 15.1(4)M2 or 3.13.8S :
[ ] [Check]
By default, the Cisco Software Checker includes results only for
vulnerabilities that have a Critical or High Security Impact Rating (SIR).
To include results for Medium SIR vulnerabilities, customers can use the
Cisco Software Checker on Cisco.com and check the Medium check box in the
drop-down list under Impact Rating when customizing a search.
For a mapping of Cisco IOS XE Software releases to Cisco IOS Software
releases, refer to the Cisco IOS XE 2 Release Notes , Cisco IOS XE 3S
Release Notes , or Cisco IOS XE 3SG Release Notes , depending on the Cisco
IOS XE Software release.
Exploitation and Public Announcements
o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
any public announcements or malicious use of the vulnerability that is
described in this advisory.
Source
o This vulnerability was found by Victor Kamensky of Cisco during internal
security testing.
Cisco Security Vulnerability Policy
o To learn about Cisco security vulnerability disclosure policies and
publications, see the Security Vulnerability Policy . This document also
contains instructions for obtaining fixed software and receiving security
vulnerability information from Cisco.
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-iox-usb-guestshell-WmevScDj
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-SEP-24 |
+----------+---------------------------+----------+--------+--------------+
- --------------------------END INCLUDED TEXT--------------------
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