A vulnerability in the DNS code of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to cause an affected system to reload. The vulnerability is due to improper processing of DNS packets. An attacker could exploit this vulnerability by sending a crafted request to an affected Cisco ASA device to cause it to generate a DNS request packet. The attacker would need to spoof the reply packet with a crafted DNS response. Note: This vulnerability can be exploited only by traffic that is directed to the affected device. This vulnerability affects Cisco ASA Software configured in routed or transparent firewall mode and single or multiple context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic. This vulnerability is documented in Cisco bug ID CSCuu07799 (registered customers only) and Common Vulnerabilities and Exposures (CVE) ID CVE-2015-6326. Cisco has released software updates that address this vulnerability. Workarounds that mitigate this vulnerability are not available. This advisory is available at the following link: http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151021-asa-dns2
Vulmon
ciscoasa# show running-config dns server-group
DNS server-group DefaultDNS
name-server 192.168.1.1
.
.
.
Note: By default, the DNS name-server value is not configured in any DNS server group.ciscoasa# show version | include Version
Cisco Adaptive Security Appliance Software Version 9.2(1)
Device Manager Version 7.4(1)
In all cases, customers should ensure that the devices to upgrade 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.
In the following table, the left column lists major releases of Cisco ASA Software. The center column indicates whether a major release is affected by the vulnerability described in this advisory and the first minor release that includes the fix for this vulnerability. The right column indicates whether a major release is affected by all the vulnerabilities described in the following advisories and which release includes fixes for those vulnerabilities:
| Cisco ASA Major Release | First Fixed Release for This Vulnerability | First Fixed Release for All Vulnerabilities in the October 2015 ASA Security Advisory Bundled Publication |
|---|---|---|
| 7.2 | Affected; migrate to 8.2(5.58) or later | Affected; migrate to 8.2(5.58) or later |
| 8.2 | 8.2(5.58) | 8.2(5.58) and later |
| 8.3 | Affected; migrate to 8.4(7.29) or later | Affected; migrate to 8.4(7.29) or later |
| 8.4 | 8.4(7.29) | 8.4(7.29) |
| 8.5 | Affected; migrate to 9.0(4.37) or later | Affected; migrate to 9.0(4.37) or later |
| 8.6 | Affected; migrate to 9.0(4.37) or later | Affected; migrate to 9.0(4.37) or later |
| 8.7 | 8.7(1.17) | 8.7(1.17) and later |
| 9.0 | 9.0(4.37) | 9.0(4.37) and later |
| 9.1 | 9.1(6.6) | 9.1(6.8) and later |
| 9.2 | 9.2(4) | 9.2(4) and later |
| 9.3 | 9.3(3.6) | 9.3(3.6) and later |
| 9.4 | 9.4(1.5) | 9.4(2) and later |
| 9.5 | Not affected | Not affected |
Cisco ASA Software can be downloaded from the Software Center on Cisco.com by visiting http://www.cisco.com/cisco/software/navigator.html.
For Cisco ASA 5500 Series Adaptive Security Appliances and Cisco ASA 5500-X Next Generation Firewall, navigate to the following path. To find interim versions, click All Releases > Interim on the left side of the download page.
Products > Security > Firewalls > Adaptive Security Appliances (ASA) > ASA 5500 Series Adaptive Security Appliances >For the Cisco ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers, navigate to the following path. To find interim versions, click All Releases > Interim on the left side of the download page.> Adaptive Security Appliance (ASA) Software
Products > Cisco Interfaces and Modules > Services Modules > Catalyst 6500 Series / 7600 Series ASA Services Module > Adaptive Security Appliance (ASA) SoftwareFor the Cisco ASA 1000V Cloud Firewall, navigate to the following path:
Products > Security > Firewalls > Adaptive Security Appliances (ASA) > ASA 1000V Cloud FirewallFor the Cisco Adaptive Security Virtual Appliance (ASAv), navigate to the following path:
Products > Security > Firewalls > Adaptive Security Appliances (ASA) > Adaptive Security Virtual Appliance (ASAv) > Adaptive Security Appliance (ASA) SoftwareFor the Cisco FirePOWER 9300 ASA Module, navigate to the following path:
Products > Security > Firewalls > Adaptive Security Appliances (ASA) > Firepower 9000 Series > Firepower 9300 Security Appliance >Adaptive Security Appliance (ASA) Software
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.
| Version | Description | Section | Status | Date |
|---|---|---|---|---|
| 1.1 | Corrected first fixed and recommended release version for Cisco ASA 9.3 train. | Fixed Software | Final | 2015-November-12 |
| 1.0 | Initial public release. | - | Final | 2015-October-21 |
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