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New vulnerability discovered in Cisco ASA, ASAx and Firepower devices

New vulnerability discovered in Cisco ASA, ASAx and Firepower devices

A new vulnerability was publicly announced last Friday (22th of June). It effects all current Cisco ASA devices (all models) and Firepower appliances (please see full list below).

It allows a remote attacker to execute a DoS (Denial-Of-Service) attack towards the vulnerable device and potentially extract sensitive data from the device (credential usernames and active sessions). It exploits the HTTP(S) service on the devices and uses directory traversal to try to gather sensitive data and potential reload the device. The vulnerability is possible due to lack of proper input validation of the HTTP URLs.

The discovery was made by a Polish Security researcher named Michal Bentkowski and was initially shared only with Cisco, giving time for Cisco to prepare patches and updates to its software. There have already been real-life attempts in exploiting this vulnerability due its lack of complexity and how easy it is to do it – there is already a couple of scripts on the internet to automate the process (see links below). Cisco states there is no work-around for this problem and all its customers are urged to upgrade to the patched software that Cisco has released prior to the unveiling of the vulnerability.

How to check if your devices are vulnerable:

If you have not patched your devices since the 22th of June and are using ASDM/CSM or Anyconnect on a publicly facing interface then it is very likely you are affected.

Simple steps to validate if your devices are vulnerable

1. Check if your devices is listening on SSL ports

 ciscoasa# show asp table socket | include SSL|DTLS

Look for open sockets on public facing interfaces

2. Check for presence of a process called Unicorn Proxy Thread, if this process is present, your device is considered vulnerable

ciscoasa# show processes | include Unicorn
Mwe 0x0000557f9f5bafc0 0x00007f62de5a90a8 0x0000557fa52b50a0
 3632 0x00007f62c8c87030 30704/32768 Unicorn Proxy Thread 218

Look for open sockets on public facing interfaces

Affected models:

  • 3000 Series Industrial Security Appliance (ISA)
  • ASA 1000V Cloud Firewall
  • ASA 5500 Series Adaptive Security Appliances
  • ASA 5500-X Series Next-Generation Firewalls
  • ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers
  • Adaptive Security Virtual Appliance (ASAv)
  • Firepower 2100 and 4100 Series Security Appliance
  • Firepower 9300 ASA Security Module
  • FTD Virtual (FTDv)

Fixed Releases:


Customers should upgrade to an appropriate release as indicated in the following tables.

Cisco ASA Software

Cisco ASA Software ReleaseFirst Fixed Release for This Vulnerability
Prior to 9.11Migrate to 9.1.7.29
9.1 9.1.7.29
9.29.2.4.33
9.3 Migrate to 9.4.4.18
9.49.4.4.18
9.5Migrate to 9.6.4.8
9.69.6.4.8
9.79.7.1.24
9.89.8.2.28
9.99.9.2.1

Cisco FTD Software

Cisco FTD Software ReleaseFirst Fixed Release for This Vulnerability
6.0Migrate to 6.1.0 HotFix or later
6.0.1Migrate to 6.1.0 HotFix or later
6.1.0Cisco_FTD_Hotfix_EI-6.1.0.7-2.sh (all FTD hardware platforms except 41xx and 9300)
Cisco_FTD_SSP_Hotfix_EI-6.1.0.7-2.sh (41xx and 9300 FTD hardware platforms)
6.2.0Not vulnerable
6.2.1Migrate to 6.2.2.3
6.2.26.2.2.3
6.2.36.2.3.1
6.2.3-851
6.2.3-85.02

Cisco Umbrella image

Cisco Umbrella – light, easy to deploy and powerful

Cisco Umbrella image

Cisco currently has multiple endpoint security solutions in place – CWS (Cloud Web Security / Scansafe), Umbrella (OpenDNS) and AMP for endpoints are prime examples. AMP is a different breed of endpoint protection, it relies heavily on detection based on heuristics and cloud sandboxing, where as CWS and OpenDNS both concentrate very strongly on making sure your Internet browsing is secure and save.

A bit of history behind the story: when Cisco acquired Scansafe and then sometime later OpenDNS, a lot of people were wondering why Cisco needs two products that have such a large overlap in functionality. At first CWS looked like it was going to last, it had a large customer base, was heavily pushed by Cisco Sales and managed to get a big boost from existing Cisco customers that needed protections for this security gap which was opened by remote/roaming employees.

OpenDNS with most of its customers using the free version seemed like an outsider. It could only detect things based on DNS and was not tunneling any traffic back to the cloud, so it seems like it is not going to be a valid corporate level endpoint protections tool. People underestimated the power of DNS. OpenDNS has something very valuable, via its free version, it had the ability to see a large percentage of worldwide DNS request and using its strong security team it provided a more universal and complete protections that focuses on more than just web browsing. Almost all internet communication is based on DNS, the use of static IPs has been greatly reduced for couple of reasons – for non-malicious users the DNS provides first ease of use and flexibility that static IPs could not, for malicious users – the use of static IPs proved to be unwise as IPs were very quickly blocked (blacklisted) by ISPs and security tools. The result of massive DNS use was that your DNS provider could actively see where your traffic is going and block it (monitoring and enforcement) for all applications (not only Web based).

It was clear Cisco would have to make a choice and I believe they have made the correct one – Cisco is moving forward with the Umbrella and retiring the CWS.

What is Umbrella?

In short, the paid version of OpenDNS, which can support and integrate with other Cisco Products.

How does it work?

It works by forwarding DNS request to OpenDNS servers, either by registering your public IP with Umbrella and forwarding your internal DNS to OpenDNS servers, or by setting your network equipment (DHCP) to directly give out OpenDNS servers for DNS usage, in case the company does not have own internal DNS servers. That secures devices within the offices of the company. For Roaming devices, Umbrella has a Roaming Client (a small agent installed on endpoints, supports Windows and MACs, with vision to support Linux in the future) that makes sure all DNS requests are forwarded to the OpenDNS cloud.

It is very important to note that Umbrella does not work like a traditional Web Proxy, it does not send the all user traffic to the cloud for inspection, it only works and makes decisions based on the information from the DNS requests from the client. User traffic is send for inspection to the cloud only for gray/risky domains (traffic to malicious ones is blocked straight away). Furthermore, this redirection of traffic works for both Agent and Agentless deployments by using the DNS reply to forward the traffic to the Umbrella Cloud proxy service called Umbrella Intelligent Proxy.

The result is a better user experience (instantaneous decision to allow and block traffic to majority of traffic based on good and bad domains), lower deployment complexity and lower operational costs.

How is it configured?

Umbrella is one of the easiest deployments we have seen. It has excellent documentation and simple steps to help you redirect your office traffic to the cloud and deploy Roaming clients to your endpoints. All the management is done via portal in the web (https://dashboard.umbrella.com/). It has a very simple and effective portal layout with intuitive access to both management entities (managed identities and policies) but also monitoring and reporting. A typical simple implementation of Umbrella can be done in a matter of hours, without the need of any on-premise hardware installations (except when AD integration is needed, a lightweight virtual server needs to be installed)

Does it support AD integration for enhanced user visibility?

Yes, it does, it needs a VA (Virtual Appliance, a lightweight virtual server running on either ESX or Hyper-V). The VA servers allows Umbrella to see internal information such as private IP addresses of users and further performs an AD integration with MS AD (servers as a connector) so Umbrella Dashboard can see AD names and be able to define policies based on groups and create reports that include clients AD username (very handy if you want to know who exactly is making all of these malicious outbound requests (such as Command and Control traffic et).

Can it block based on connections that do not use DNS?

Yes, it can, there is a functionality called IP Layer Enforcement that builds IPSEC tunnels to the Umbrella cloud and forward requests to it in case the connection has a suspicious (flagged as malicious) IP address. This is possible only if the client is using Roaming Agent (either the Umbrella one or Anyconnect one).

Does it have integration with other Cisco products?

Umbrella has a module for Anyconnect (Cisco Umbrella Roaming Security module is available for Anyconnect version 4.3 MR1 and newer), which means if the customer has Anyconnect already deployed, there is no need to install Umbrella Roaming Agent. Also, OpenDNS security team is now part of Cisco Talos so OpenDNS both feeds Talos with DNS information but also benefits from Talos to device either certain domain or IP address are deemed risky.

Does it support SSL decryption?

Yes, Umbrella supports SSL decryption so it can do deep inspection for traffic destined for risky/suspicious domains. The configuration of the SSL decryption is very straight-forward, administrators are prompted to download Umbrella (OpenDNS) certificated from the Dashboard and then these certificates need to be installed as trusted on endpoint machines. Next step is just to enable the SSL decryption.

Conclusion:

Umbrella provides enterprise level endpoint security with lower latency than traditional proxies, low capex and deployment costs.

References:

http://www.cisco.com/c/en/us/products/collateral/security/cloud-web-security/eos-eol-notice-c51-738244.html

https://support.umbrella.com/hc/en-us/articles/231246528-Umbrella-Intelligent-Proxy-FAQs

https://umbrella.cisco.com/products/features/intelligent-proxy

https://deployment-umbrella.readme.io/docs/1-introduction

https://deployment-umbrella.readme.io/docs/1-ad-integration-setup-overview

https://deployment-umbrella.readme.io/docs/anyconnect-umbrella-roaming-security-client-administrator-guide