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AUSCERT External Security Bulletin Redistribution
ESB-2018.2379
Cisco Web Security Appliance Multiple Vulnerabiltities
16 August 2018
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco Web Security Appliance (WSA)
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Root Compromise -- Existing Account
Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2018-0428 CVE-2018-0410
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180815-wsa-dos
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180815-wsa-escalation
Comment: This bulletin contains two (2) Cisco Systems security advisories.
- --------------------------BEGIN INCLUDED TEXT--------------------
Cisco Web Security Appliance Web Proxy Memory Exhaustion Denial of Service
Vulnerability
High
Advisory ID: cisco-sa-20180815-wsa-dos
First Published: 2018 August 15 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs:
CVE-2018-0410
CWE-400
CVSSÂ Score:
8.6 AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
Summary
o A vulnerability in the web proxy functionality of Cisco AsyncOS Software
for Cisco Web Security Appliances could allow an unauthenticated, remote
attacker to exhaust system memory and cause a denial of service (DoS)
condition on an affected system.
The vulnerability exists because the affected software improperly manages
memory resources for TCP connections to a targeted device. An attacker
could exploit this vulnerability by establishing a high number of TCP
connections to the data interface of an affected device via IPv4 or IPv6.
A successful exploit could allow the attacker to exhaust system memory,
which could cause the system to stop processing new connections and result
in a DoS condition. System recovery may require manual intervention.
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-20180815-wsa-dos
Affected Products
o Vulnerable Products
This vulnerability affects Cisco AsyncOS Software Releases 9.1, 10.1,
10.5, and 11.0 for Cisco Web Security Appliances, both virtual and
hardware appliances, if the HTTPS Proxy feature is enabled. By default,
the HTTPS Proxy feature is disabled.
For more information about which Cisco AsyncOS Software releases are
vulnerable, see the Fixed Software section of this advisory.
To determine whether a vulnerable release of Cisco AsyncOS Software is
running on a Cisco Web Security Appliance (WSA), administrators can use
the version command in the WSA CLI. The following example shows the output
of the command for a WSA that is running Cisco AsyncOS Software Release
10.5.2-072:
ciscowsa> version
Current Version
===============
Product: Cisco S670 Web Security Appliance
Model: S670
Version: 10.5.2-072
.
.
.
To determine whether the HTTPS Proxy feature is enabled for a WSA,
administrators can log in to the web interface of the WSA and navigate to
Security Services > HTTPS Proxy. The value in the HTTPS Proxy field
indicates whether the feature is enabled or disabled.
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:
Email Security Appliance (ESA), both virtual and hardware appliances
Security Management Appliance (SMA), both virtual and hardware
appliances
Indicators of Compromise
o Exploitation of this vulnerability will cause the affected software to
stop releasing memory resources that were allocated to established TCP
connections, which could exhaust system memory on a device.
Administrators can assess the current status of device connections by
using the netstat command in the device CLI. If the output of the command
indicates an accumulation of TCP connections in the CLOSE_WAIT state, the
device may be affected by this vulnerability. The following example shows
the output of the netstat command for a device that has not released
memory resources for several TCP connections running over IPv4 and IPv6,
respectively:
ciscowsa> netstat
.
.
.
Active Internet connections (including servers)
Proto Recv-Q Send-Q Local Address Foreign Address (state)
tcp4 0 0 127.0.0.1.25255 127.0.0.1.36586 TIME_WAIT
tcp4 112 0 127.0.0.1.443 127.0.0.1.9310 CLOSE_WAIT
tcp4 0 0 127.0.0.1.9310 127.0.0.1.443 FIN_WAIT_2
tcp4 0 0 127.0.0.1.25255 127.0.0.1.21834 TIME_WAIT
tcp4 112 0 127.0.0.1.443 127.0.0.1.36782 CLOSE_WAIT
tcp4 0 0 10.1.1.51.32969 1.1.1.1.443 ESTABLISHED
tcp6 112 0 ::1.443 ::1.48808 CLOSE_WAIT
tcp4 0 0 10.1.1.51.443 *.* LISTEN
tcp6 0 0 ::1.443 *.* LISTEN
tcp4 0 0 127.0.0.1.443 *.* LISTEN
.
.
.
To recover memory resources on a device, administrators can reboot the
device or restart the web proxy process. To restart the web proxy process,
administrators can use the hidden diagnostic > PROXY > kick command in the
device CLI, for example:
ciscowsa> diagnostic
Choose the operation you want to perform:
- NET - Network Diagnostic Utility.
- PROXY - Proxy Debugging Utility.
- REPORTING - Reporting Utilities.
[]> proxy
- SNAP - Take a snapshot of the proxy
- OFFLINE - Take the proxy offline (via WCCP)
- RESUME - Resume proxy traffic via (via WCCP)
- CACHE - Clear proxy cache
[]> kick
Kick the proxy
Are you sure you want to proceed [N]> Y
Note that web proxy services will be temporarily unavailable while the web
proxy process restarts.
Workarounds
o There are no workarounds that address this vulnerability.
Fixed Software
o Cisco has released free software updates that address the vulnerability
described in this advisory. Customers may only install and expect support
for software versions and feature sets for which they have purchased a
license. By installing, downloading, accessing, or otherwise using such
software upgrades, customers agree to follow the terms of the Cisco
software license:
https://www.cisco.com/c/en/us/products/end-user-license-agreement.html
Additionally, customers may only download software for which they have a
valid license, procured from Cisco directly, or through a Cisco authorized
reseller or partner. In most cases this will be a maintenance upgrade to
software that was previously purchased. Free security software updates do
not entitle customers to a new software license, additional software
feature sets, or major revision upgrades.
When considering software upgrades, customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories and Alerts 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.
Customers Without Service Contracts
Customers who purchase directly from Cisco but do not hold a Cisco service
contract and customers who make purchases through third-party vendors but
are unsuccessful in obtaining fixed software through their point of sale
should obtain upgrades by contacting the Cisco TAC:
https://www.cisco.com/c/en/us/support/web/
tsd-cisco-worldwide-contacts.html
Customers should have the product serial number available and be prepared
to provide the URL of this advisory as evidence of entitlement to a free
upgrade.
Fixed Releases
Customers are advised to upgrade to an appropriate release as indicated in
the following table:
Cisco AsyncOS Software Major Release First Fixed Release
Prior to 9.1 Migrate to 10.1.3-054 or later
9.1 Migrate to 10.1.3-054 or later
10.1 10.1.3-054
10.5 10.5.2-072
11.0 11.5.0-614
11.5 Not vulnerable
In most cases, the software can be upgraded over the network by using the
System Upgrade options in the web interface of the WSA. To upgrade a
device by using the web interface:
1. Choose System Administration > System Upgrade.
2. Click Upgrade Options.
3. Choose Download and Install.
4. Choose the release to upgrade to.
5. In the Upgrade Preparation area, choose the appropriate options.
6. Click Proceed to begin the upgrade. A progress bar displays the status
of the upgrade.
After the upgrade is complete, the device reboots.
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 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.
Subscribe to Cisco Security Notifications
o Subscribe
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180815-wsa-dos
Revision History
o +----------+---------------------------+----------+--------+-----------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+-----------------+
| 1.0 | Initial public release. | - | Final | 2018-August-15 |
+----------+---------------------------+----------+--------+-----------------+
=============================================================================
Cisco Web Security Appliance Privilege Escalation Vulnerability
Medium
Advisory ID: cisco-sa-20180815-wsa-escalation
First Published: 2018 August 15 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs:
CVE-2018-0428
CWE-284
CVSSÂ Score:
6.7 AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:X/RL:X/RC:X
Summary
o A vulnerability in the account management subsystem of Cisco Web Security
Appliance (WSA) could allow an authenticated, local attacker to elevate
privileges to root. The attacker must authenticate with valid
administrator credentials.
The vulnerability is due to improper implementation of access controls. An
attacker could exploit this vulnerability by authenticating to the device
as a specific user to gain the information needed to elevate privileges to
root in a separate login shell. A successful exploit could allow the
attacker to escape the CLI subshell and execute system-level commands on
the underlying operating system as root.
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-20180815-wsa-escalation
Affected Products
o Vulnerable Products
This vulnerability affects Cisco Web Security Appliance (WSA). For
information about affected software releases, consult the Cisco bug ID(s)
at the top of this advisory.
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:
Email Security Appliance (ESA), both virtual and hardware versions
Content Security Management Appliance (SMA), both virtual and hardware
versions
Workarounds
o There are no workarounds that address this vulnerability.
Fixed Software
o For information about fixed software releases, consult the Cisco bug ID(s)
at the top of this advisory.
When considering software upgrades, customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories and Alerts 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.
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 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.
Subscribe to Cisco Security Notifications
o Subscribe
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180815-wsa-escalation
Revision History
o +----------+---------------------------+----------+--------+-----------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+-----------------+
| 1.0 | Initial public release. | - | Final | 2018-August-15 |
+----------+---------------------------+----------+--------+-----------------+
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