Cisco Security

Why do legacy ASAs need Migration to ASA X Generation?

Cisco Security

The traditional legacy ASA Firewalls (5505, 5510, 5520, 5540, 5580) are End of Life (EOL) and soon will be End of Support (EOS). There are still a vast number of ASA’s in the public realm used as a security device/internet edge firewalls where many companies think they are providing the necessary security, the reality cannot be further from the truth.

These older model ASA’s have the following problems

  1. Hardware Problems

Cisco ASA Firewalls have a Meantime-Between-Failure (MTBF) which is simply the predicted elapsed time between inherent failures of such devices. When legacy ASA’s are out of support it is not possible to renew support contracts as Firmware updates are no longer available, effectively making the devices EOL. Meaning they are a ticking bomb and without support any network can suffer significant downtime when the device gives up.

  1. Code Vulnerabilities

ASA updates are uncommon, occurring every 6 months or so, meaning security holes can appear with such a time gap between security patch updates. Effectively your device is vulnerable and unsecured whilst it awaits the next patch update. Currently legacy ASA Firewalls only run to version 9.1 updates. These vulnerability problems wouldn’t be a threat if default and most deployed scenario is an Internet Edge Firewall.

  1. Lack of new features

Cisco is not deploying any new features to the legacy ASA’s and the major version will probably not move away from 9.1 (when the newest is 9.6 for next generation Firewalls)

  1. Lack of real security

Any working firewall cannot only rely on the Stateful Firewall technology for protecting the assets of an organization. Legacy ASA’s can only run the legacy Cisco IPS with a separate module which cannot measure to the modern IPS technology. The new generation of firewalls have the Firepower functionality which is the industry leading IPS technology.

Challenges for migrating Legacy ASA to ASA X?

  1. Configuration migration
  • Manual migration – Configuration between Legacy ASA’s and the new ASA X usually differs and cannot be simply copied and pasted into the new device. Different naming for interfaces and different features and functionalities means different syntax for the CLI.

Very often the legacy ASA’s run a pre-8.3 code due to RAM restrictions (RAM needs to be upgraded for post 8.3+ code). The pre-8.3 code is very different from today’s code in terms of syntax. It does mandate the obligatory use of objects, the NATs are the old PIX like fashion and any policies use the global ip addresses (the so called real ip addresses seen on the interface) than the original one (the ip addresses on the hosts). That means that large portions of the config need to be redone (in most cases manually) when you do the switch over.

The sections that needs manual work are: Objects, NATs, Policies and ACLs. That is the recommended approach and usually an experienced Cisco Security Consultant is needed to perform the job.

  • Automatic migration is possible if the legacy ASA has its RAM upgraded (512MB for 5505 and more than 1GB for the other models is mandatory). Depending on the starting OS Image version several upgrades are done to ensure the device runs the latest 8.2.x code and then jump to 8.4.1. During that jump the device will automatically redo the configuration to its best (will shout out errors on console while booting if it cannot migrate certain areas of the config), it will create objects (with automatic names) and will deploy them.

During automatic migrations, there is always a chance that something will not work so the migration again needs to be performed by someone who understands the migration process, can track down and manually intervene to correct errors or add configuration after the migration. Also, the configuration after an automatic migration is not easily readable due to the creation of objects with automatic naming convention.

  • Raising the security level – if you migrated from a legacy ASA to a new generation ASA X that supports other security technologies and Firepower then it makes sense to leverage new technologies and enable/configure/tune them. A blind one-to-one migration might give you more in the world of availability (new hardware, newer code, less code vulnerabilities and frequent code updates), but will not give you ultimately better protection for your assets. A deep packet inspection with content analysis is a must in the modern threat landscape. Implementing the Firepower technology is necessary but a complex step that needs to be done by people with the right skillset and experience.

References:

  1. EOS / EOL announcement

http://www.cisco.com/c/en/us/products/collateral/security/asa-5500-series-next-generation-firewalls/eol_C51-727283.html