Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Perimeter

9/1/2010
08:30 AM
John H. Sawyer
John H. Sawyer
Commentary
50%
50%

Finding Exposed Devices On Your Network

When browsing through SHODAN, it never ceases to amaze me what I can find. How is it that people think it's okay to leave their printers, routers, fiber channel switches, and industrial control systems completely open to the Internet?

When browsing through SHODAN, it never ceases to amaze me what I can find. How is it that people think it's okay to leave their printers, routers, fiber channel switches, and industrial control systems completely open to the Internet?In case you're not sure what SHODAN is, I've mentioned SHODAN a few times in previous articles and blogs like "Gaining A Foothold By Exploiting VxWorks Vulns." It's been referred to as a rainbow table for Internet-accessible computers because it provides a searchable index of service banners retrieved from HTTP, HTTPS, FTP, SSH, and telnet services on the Internet without the need to do any of your own scanning.

When I was looking at the VxWorks vulnerability, I found vulnerable printers, network switches, fiber channel switches, and industrial control systems (or SCADA) equipment through some simple searches that are mentioned in this blog.

So I'm left wondering who thought it was a good idea to put these devices on the Internet without some sort of protection in place. Is there no change management procedures at these organizations where someone should be monitoring what's taking place on the network? Surely someone has to provision the public IP for use for the devices. Why aren't they asking what the IP will be used for and if the device is being locked down?

Sure, you can use SHODAN to check your netblocks for exposed devices that you might not be aware of, but why not be a little more proactive? Isn't proactive security better than reactive security? Or more to the point, wouldn't you rather find out about a new exposed device on you network before an attacker does?

There are a couple ways to go about this. The first is setting up some simple network scans using Nmap. It could be done daily or weekly, but I wouldn't recommend going as long as a month in between scans. Be sure to set up the scans to save the output to the Nmap XML format. Once you have more than one scan, you can use the Ndiff utility to compare the two scans and determine if there are any state changes for hosts, ports, service versions, operating systems, and the output of scripts.

The Nmap route is cheap and easy to implement, but if you have a nice netflow analysis solution like Lancope's StealthWatch, it can be done even easier. All of the netflow monitoring tools I've seen have an alert option that will notify admins when a new host is seen communicating on the network. I've also seen alerts for when a host begins acting as a server for the first time. For example, if a host is on the network and begins accepting and responding to requests on TCP port 443 for the first time, admins will receive an alert.

Security teams are often the last ones to know when new systems are brought online, but they don't have to be. Using the tools above, security can know when new systems show up on the network and take appropriate actions such as a vulnerability scan, and confirm that the device is authorized and not some rogue wireless router an employee decided to plug in so they could use their new iPad.

John H. Sawyer is a senior security engineer on the IT Security Team at the University of Florida. The views and opinions expressed in this blog are his own and do not represent the views and opinions of the UF IT Security Team or the University of Florida. When John's not fighting flaming, malware-infested machines or performing autopsies on blitzed boxes, he can usually be found hanging with his family, bouncing a baby on one knee and balancing a laptop on the other. Special to Dark Reading.

Comment  | 
Print  | 
More Insights
Comments
Newest First  |  Oldest First  |  Threaded View
Stop Defending Everything
Kevin Kurzawa, Senior Information Security Auditor,  2/12/2020
Small Business Security: 5 Tips on How and Where to Start
Mike Puglia, Chief Strategy Officer at Kaseya,  2/13/2020
5 Common Errors That Allow Attackers to Go Undetected
Matt Middleton-Leal, General Manager and Chief Security Strategist, Netwrix,  2/12/2020
Register for Dark Reading Newsletters
White Papers
Video
Cartoon
Current Issue
6 Emerging Cyber Threats That Enterprises Face in 2020
This Tech Digest gives an in-depth look at six emerging cyber threats that enterprises could face in 2020. Download your copy today!
Flash Poll
How Enterprises Are Developing and Maintaining Secure Applications
How Enterprises Are Developing and Maintaining Secure Applications
The concept of application security is well known, but application security testing and remediation processes remain unbalanced. Most organizations are confident in their approach to AppSec, although others seem to have no approach at all. Read this report to find out more.
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
CVE-2019-20477
PUBLISHED: 2020-02-19
PyYAML 5.1 through 5.1.2 has insufficient restrictions on the load and load_all functions because of a class deserialization issue, e.g., Popen is a class in the subprocess module. NOTE: this issue exists because of an incomplete fix for CVE-2017-18342.
CVE-2019-20478
PUBLISHED: 2020-02-19
In ruamel.yaml through 0.16.7, the load method allows remote code execution if the application calls this method with an untrusted argument. In other words, this issue affects developers who are unaware of the need to use methods such as safe_load in these use cases.
CVE-2011-2054
PUBLISHED: 2020-02-19
A vulnerability in the Cisco ASA that could allow a remote attacker to successfully authenticate using the Cisco AnyConnect VPN client if the Secondary Authentication type is LDAP and the password is left blank, providing the primary credentials are correct. The vulnerabilities is due to improper in...
CVE-2015-0749
PUBLISHED: 2020-02-19
A vulnerability in Cisco Unified Communications Manager could allow an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack on the affected software. The vulnerabilities is due to improper input validation of certain parameters passed to the affected software. An attacker ...
CVE-2015-9543
PUBLISHED: 2020-02-19
An issue was discovered in OpenStack Nova before 18.2.4, 19.x before 19.1.0, and 20.x before 20.1.0. It can leak consoleauth tokens into log files. An attacker with read access to the service's logs may obtain tokens used for console access. All Nova setups using novncproxy are affected. This is rel...