Tag: security

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Is Your Network At Risk – Automating the Cisco PSIRT with Genie and Ansible

The security of my network keeps me up at night. Honestly it does. We live in a world where enterprise networks are defending themselves against state-sponsored attacks. But what do attackers look for? Typically, open, well-known, vulnerabilities.

Well, at least to the hackers, attackers, and even script-kiddies, these vulnerabilities are well-known. Those playing defense are often a step or two behind just identifying vulnerabilities – and often times at the mercy of patch-management cycles or operational constraints that prevent them of addressing (patching) these waiting-to-be-exploited holes in the network.

What can we do about it?

The first thing we can do is to stay informed ! But this alone can be a difficult task with a fleet of various platforms running various software versions at scale. How many flavours of Cisco IOS, IOS-XE, and NXOS platforms make up your enterprise? What version are they running? And most importantly is that version compromised?

The old way might be to get e-mail notifications (hurray more e-mail!), maybe RSS-feeds, or go device-by-device, webpage-by-webpage, looking up the version and if it’s open to attack or not.

Do you see why, now, how an enterprise becomes vulnerable? It’s tedious and time-intensive work. And the moment you are done – the data is stale – what, are you going to wake up every day and review threats like this manually? Assign staff to do this? Just accept the risk and do they best you can trying to patch quarterly ?

Enter: Automation

These types of tasks beg to be solved with automation !

So how can you do it?

Let’s just lay out a high level, human language, defined use-case / wish list.

  1. Can we, at scale, go get the current IOS / IOS-XE / NXOS software version from a device?
  2. Then can we send that particular version somewhere to find out if it has been compromised ?
  3. Can we generate a report from the data above?

Technically the above is all feasible; easy even!

  1. Yes, we can use Ansible and the Cisco Genie Parser to capture the current software version
  2. The Cisco Product Security Incident Response Team has incredible, secure, REST APIs available that we can automate with the Ansible URI module
  3. Using Jinja2 templates we can craft business-ready reports

Getting Started

First you need to setup your Cisco.com REST API suite access

Pre-Ansible Development

As with any new REST API I like to start with Postman and then transform working requests into Ansible playbooks.

First, under a new or existing Cisco.com Collection, add a new request called IOS Vulnerabilities

Cisco.com uses OAuth2 authentication mechanism where you first must authenticate against one REST API (https://cloudsso.cisco.com/as/token.oauth2) which provides back authorization Bearer token used to then authenticate and authorize against subsequent Cisco.com APIs

Your Client ID and Secret are found in the API portal after you register the OpenVuln API

Request and use a token from the API in Postman:

Now add your request for IOS

https://api.cisco.com/security/advisories/ios?version=

Test it out!

Let’s hard code a version and see what flaws it has

Ok so it has at least 1 open vulnerability!

Does it tell us what version fixes it?

Ok let’s check that version quickly while we are still in Postman

This version has no disclosed vulnerabilities!

One interesting thing of note – and our automation is going to need to handle it – is that if there are no flaws found we get a 404 back from the API not a 200 like our flawed response!

The Playbook

For the sake of the example I am using prompted inputs / response but these variables could easily be hardcoded and Ansible Vaulted.

So first prompt for your Cisco hosts username and password and your Cisco.com ClientID and Client Secret

Register the response

Then in the IOS.yml group_vars I have my Ansible network connections

I’ve put all IOS-platforms in this group in the hosts file to target them

Next step run the show version ios_command and register the reponse

Genie parse and register the JSON

Now we need, just like in Postman, to go get the OAuth2 token but instead of Postman we need to use the Ansible URI module

Then we have to parse this response and setup our Bearer and Token components from the response JSON.

Now that we have our token we can authenticate against the IOS open Vulernability API

There are a couple of things going on here:

  1. We are passing the Genie parsed .version.version key to the API for each IOS host in our list
  2. We are using the {{ token_type }} and {{ access_token }} to Authorize
  3. We have to expect two different status codes; 200 (flaws found on a host) and 404 (no flaws for the host software version)
  4. I’ve added until and delay to slow down / throttle the API requests as not to get a 406 back because I’ve overwhelmed the 10 requests per second upper limit
  5. We register the JSON response from the API

As always I like to create a “nice” (easy to read) version of the output in a .json file

Note we need to Loop over each host in our playbook (using the Ansible magic variable ansible_play_hosts) so the JSON file has a data set for each host in the playbook.

Lastly we run the template module to pass the data into Jinja2 where we will create a business-ready CSV file

Which looks like this broken apart:

Like building the JSON file first we need to loop over the hosts in the playbook.

Then we check if the errorCode is defined. You could also look at the 404 status code here. Either way if you get the error it means there are no vulnerabilities.

So add a row of data with the hostname, “N/A” for most fields, and the json.errorMessage from the API (or just hardcode “No flaws” or whatever you want here; “compliant”)

Now if the errorCode is not defined it means there are open flaws and we will get back other data we need to loop into.

I am choosing to do a nested set of two loops – one for each advisory in the list of advisories per software version. Then inside that loop another loop, adding a row of data to the spreadsheet, for each BugID found as well (which is also a list).

There are a few more lists like CVEs for example – you can either loop of these as well (but we start to get into too much repetition / rows of data) – or just use regex_replace(‘,’,’ ‘) to remove all commas inside a field. The result is the list spaced out inside the cell sorted alphabetically but if you do not do this it will throw off the number of cells in your CSV

The results

What can you do with “just” a CSV file?

With Excel or simply VS Code with the Excel Preview extension – some pretty awesome things!

I can, for example, pick the ID field and filter down a particular flaw in the list – which would then provide me all the hosts affected by that bug

Or pick a host out of the list and see what flaws it has, if any. Or any of the columns we have setup in the Jinja2

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Included in the report is also the SEVERITY and BASE SCORE for quick decision making or the Detailed Publication URL to get a detailed report for closer analysis.

Which looks like this:

Automation is much more than configuration management. It can be used to manage, understand, and mitigate risk as well.

Together we can secure our enterprise networks and hopefully sleep a little more sound knowing they are safe.

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Prevent an Intrusion – Run the Recommended Version!

In the wake of some very high profile IT security breaches and state sponsored attacks using compromised software today I wrote some infrastructure as code Ansible playbooks to create some business-ready documentation to help us understand our Cisco software version footprint against what release the vendor recommends. It is very important to run “Safe Harbor” code in the form of the Gold Star release. These releases are as close as it gets to being bug-free, secure, tested, and supported in production environments.

The ‘old-way’ involved getting the Cisco Part ID (PID) or several PIDs and looking up the recommended release on Cisco.com using an ever deepening hierarchy of platforms, operating systems, and PIDs. At scale this is like a day’s worth of work to go gather all of this information and present it in a way the business can understand.

Building on my recent success with the Serial2Info Cisco.com API as well as Ansible Facts I thought this might be another nice use-case for business-centric, non-technical (not routes, IP addresses, mac addresses, etc), extremely important and critical insight.

Use Case

Can I automatically get the PID from a host or group of hosts and provide it to the Cisco.com Software Suggestion API building business-ready reports in CSV and markdown?

Answer: Yes!

The Playbook

Again you are going to need:

* A Linux Host with SSH access to your Cisco IOS devices and HTTPS access to the Cisco.com API
* Credentials for the host and for the OAuth2 API
* We are not using Genie parsers here so just “base” Ansible will work

Step 1. Setup credential handling

Create a playbook file called CiscoCoreRecommendedReleaseFacts.yml

Again I use prompted methodology here same as the Serial2Info API

Gather the username, enable secret, Cisco.com API ClientID, Client Secret

Step 2. Gather Ansible Facts

Using the ios_facts module gather just the hardware subset

Because we are using Ansible Facts we do not need to register anything – the JSON is stored in the Ansible magic variable ansible_facts

I need 2 keys from this JSON – the PID and ideally the current running version. These can be found as follows in the ansible_facts variable:

Which is accessed as ansible_facts.net_model

Which again is accessed as ansible_facts.net_version

With the information above – without going any further – I could already build a nice report about what platforms and running versions there are!

But let’s go a step further and find out what Cisco recommends I should be running!

Step 2. Get your OAuth2 token

First, using the Ansible URI module

We need to get our token using the registered prompted credentials.

The API requires the following headers and body formatting; register the response as a variable (token):

We have to break apart the RAW JSON token to pass it to the ultimate Recommended Release API:

Now we are ready to send PIDs to the API.

Step 3 – Send PID to Cisco.com API

Again using the URI module:

Here we pass the ansible_facts.net_model Fact to the API as an HTTP GET:

The headers and body requirements. Notice the authentication and how we pass the Bearer Token along. We also register the returned JSON:

Here is what the returned JSON looks like:

The highest level key is json or accessed via RecommendedRelease.json

There is a productlist

Which as you can see is a list as denoted by the [ ]

Inside this list is another product key with the values from the API about the product itself

A little further down we find the recommended software release

Step 4 – Transform technical documentation into business ready CSV / MD files

These JSON and YAML (I also use the | to_nice_yaml filter to create a YAML file along with the JSON file) files are create for technical purposes but we can do a bit better making the information more palatable using business formats like CSV and mark down.

It is just a matter of using Jinja2 to template the CSV and Markdown files from the structured JSON variables / key-value pairs.

Add a final task in the Ansible playbook that will loop over the CSV and MD file types using the template module to source a new .j2 file – CiscoCoreRecommendedReleaseFacts.j2 – where our logic will go to generate our artifacts.

The Jinja2 starts with an If Else EndIf statement that checks if the Ansible loop is on CSV or not. If it is it uses the CSV section of templated file format otherwise it uses markdown syntax.

First we want to add a CSV header row

Then we need a For Loop to loop over each product in the productList

Now we add our “data line” per product in the loop using the various keys

Hostname for example uses the Ansible magic variable inventory_hostname

Then we want the Base PID. We use the Ansible default filter to set a default value in case the variable happens to be empty.

We continue accessing our keys and then we close the loop.

Now we need to create the Markdown syntax

And the same logic for the “data row” but with pipes instead of commas. Make sure to close off the If statement

Step 5 – Run playbook and check results

We run the playbook as ansible-playbook CiscoCoreRecommendedReleaseFacts.yml

Answer the prompts

Let the playbook run and check the results!

Summary

Again with a few free, simple tools like Ansible and the Cisco.com API we can, at scale gather and report on the current running version and the vendor recommended version quickly and easily and fully automatically!

Now go and start protecting your enterprise network armed with these facts!