These vulnerabilities and their respective workarounds are independent of each other. The override account feature is enabled with the override-account-disable command in tunnel-group general-attributes configuration mode. As a workaround, disable this feature using the no override-account-disable command. The following example, shows how a trusted host with IP address Temporarily disabling the feature will mitigate this vulnerability.
As a workaround, remove the access-group line applied on the interface where the ACL is configured and re-apply it. For example:. In the previous example the access group called acl-inside is removed and reapplied to the inside interface. Alternatively, you can add an explicit deny ip any any line in the bottom of the ACL applied on that interface.
In the previous example, an explicit deny for all IP traffic is added at the end of access-list In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center TAC or your contracted maintenance provider for assistance.
The following table contains the first fixed software release of each vulnerability. The "Recommended Release" row indicates the releases which have fixes for all the published vulnerabilities at the time of this Advisory.
A device running a version of the given release in a specific row less than the First Fixed Release is known to be vulnerable. Cisco recommends upgrading to a release equal to or later than the release in the "Recommended Release" row of the table. The Cisco PSIRT is not aware of any public announcements or malicious use of the other vulnerabilities described in this advisory.
MacPherson and Robert J. Additional mitigation techniques that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory:.
In all cases, customers should exercise caution to be certain the devices to be upgraded contain sufficient memory and that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, contact the Cisco Technical Assistance Center TAC or your contracted maintenance provider for assistance. The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.
These vulnerabilities were found during internal testing and during the troubleshooting of a technical support service request. 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. A stand-alone copy or paraphrase of the text of this document that omits the distribution URL is an uncontrolled copy, and may lack important information or contain factual errors.
The information in this document is intended for end-users of Cisco products. Advisory ID:. First Published:. Version 1. Base 7. Vulnerable Products The following are the details about each vulnerability described within this advisory. Note: Instant Messaging Inspection is disabled by default.
ASA config telnet For example: ASA config ssh A successful attack may result in a sustained DoS condition. A Cisco ASA device configured for any of the following features is affected:.
Note: This vulnerability may be triggered when crafted packets are sent to any TCP based service that terminates on the affected device. The vulnerability may also be triggered via transient traffic only if the TCP intercept features has been enabled. A TCP three-way handshake is not needed to exploit this vulnerability.
A crafted H. The requirement of a TCP three way handshake significantly reduces the possibility of exploitation using packets with spoofed source addresses. This implicit deny is there by design, does not require any configuration and can be understood as an implicit ACE that denies all traffic reaching the end of the ACL. Note: This behavior only impacts the implicit deny statement on any ACL applied on the device. Access control lists with explicit deny statements are not affected by this vulnerability.
This vulnerability is experienced in very rare occasions and extremely hard to reproduce. You can trace the lifespan of a packet through the security appliance to see whether the packet is operating correctly with the packet tracer tool.
The packet-tracer command provides detailed information about the packets and how they are processed by the security appliance. If a command from the configuration did not cause the packet to drop, the packet-tracer command will provide information about the cause in an easily readable manner.
You can use this feature to see if the implicit deny on an ACL is not taking effect. These vulnerabilities and their respective workarounds are independent of each other.
The override account feature is enabled with the override-account-disable command in tunnel-group general-attributes configuration mode. As a workaround, disable this feature using the no override-account-disable command.
Power cycle or reload the PIX. You have ten seconds to interrupt the normal boot process. Then enter the send break command. Note: Fast Ethernet cards in bit slots are not visible in monitor mode. This problem means that the TFTP server cannot reside on one of these interfaces. Copy the PIX Appliance binary image for example, pix If you are unsure how to do this, see the instructions for how to enter Monitor Mode in this document. Note: Once in Monitor Mode, you can use the "? The default is interface 1 Inside.
Note: In Monitor Mode, the interface always auto negotiates the speed and duplex. The interface settings cannot be hard coded. You must use a Fast Ethernet interface instead. Optional Enter the IP address of your gateway. Enter the name of the file on the TFTP server that you wish to load. This is the PIX binary image file name. The pings must succeed before you continue. During the boot process, the file system is converted along with your current configuration.
However, you are not done yet. Note this Warning message after you boot and continue on to step Once booted, enter enable mode and copy the same image over to the PIX again. This time use the copy tftp flash command.
This saves the image into the Flash file system. Failure to perform this step results in a boot loop the next time the PIX reloads. Note: For detailed instructions on how to copy the image over with the use of the copy tftp flash command, see the Upgrade the PIX Security Appliance with the copy tftp flash Command section. Once the image is copied over using the copy tftp flash command, the upgrade process is complete.
Complete these steps in order to upgrade the PIX with the use of the copy tftp flash command. This message appears and indicates that the transfer is a success, the old binary image in Flash is erased, and the new image is written and installed. PIX Security Appliances versions 7. Therefore, you cannot downgrade from a 7. Instead, you must use the downgrade command. Failure to do so causes the PIX to get stuck in a boot loop.
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