Network Security Monitoring History

Recently a network forensics vendor was kind enough to spend some time on a WebEx-type session describing their product. I try to stay current with technology so I can offer suggestions to clients with budgets for commercial products.

During the talk the presenter was very excited by his company's capability to collect all traffic and examine it later for troubleshooting and security purposes. He implied this was a "new capability in this space," so I asked if he had read any of my books. He said no, but he did read my blog. It occurred to me that it might be helpful to reprint the history of NSM I wrote for Tao of Network Security Monitoring.

I'm doing this for three reasons. First, I want people to know that the ideas I've been publicly evangalizing since 2002 actually date back 10, perhaps 13 years earlier. I take credit for paying attention to smart people with whom I worked when I first started in this field. I don't take credit for inventing the idea that we need high quality network traffic to perform security investigations!

Second, I want to provide a public record of these historical capabilities. As I talk to more vendors I don't want them to think I'm "stealing their ideas," since many of "their ideas" were invented before some of their programmers graduated from elementary school.

Third, one day (perhaps in 2008 or 2009) I would like to blog again and link back to this post. Hopefully I'll have commercial tools providing these capabilities to anyone who wants them, and plenty of companies will be declaring themselves the "world's first blah" and "pioneers of blah" and so forth. I'll be happy that customers will finally have the data they need to understand what is happening in their enterprise, whatever weird, long, and contentious road was followed.

I can testify to the following history of network security monitoring because I participated in these events or have spoken directly with the participants who made the events happen. I base my understanding of the early days of NSM on information learned from Todd Heberlein and on my work with pioneers like Larry Shrader and Roberto Garcia.

NSM began as an informal discipline with Todd Heberlein’s development of the Network Security Monitor. The Network Security Monitor was the first intrusion detection system to use network traffic as its main source of data for generating alerts. Heberlein and others worked at the University of California at Davis from 1988 through 1995 on the Network Security Monitor, although by 1991 initial Network Security Monitor system research and development was complete.

The Air Force Computer Emergency Response Team (AFCERT) was the first organization to informally follow NSM principles. The AFCERT was created on October 1, 1992, partially as a result of the 1988 Morris Worm. The team began work as part of the Air Force Cryptologic Support Center at Kelly Air Force Base in San Antonio, Texas. When the Air Force Information Warfare Center (AFIWC) was activated on September 10, 1993, the AFCERT joined that unit. The AFCERT’s mission during the 1990s was to conduct Computer Network Defense (CND) operations to secure and protect the global Air Force communication and computer (C2) weapon system.

The Air Force had long recognized the need for intrusion detection systems, initially funding the Haystack host-based audit trail intrusion detection system. In 1993 the AFCERT worked with Heberlein to deploy a version of the Network Security Monitor as an Automated Security Incident Measurement (ASIM) system. The Air Force’s intent was
to measure the level of malicious activity on its networks as a way to perform threat assessment. By gaining an accurate idea of the capabilities and intentions of its adversaries, the AFCERT could position itself to acquire the funding, personnel, and responsibilities needed to properly monitor Air Force networks.

In the mid-1990s the Air Force’s network consisted of well over 100 Internet points- of-presence, but by the end of 1995 the AFCERT monitored only 26 installations. By the end of 1996 coverage had doubled to 52 Air Force bases and three “Joint” or multi-service locations. By mid-1997 ASIM sensors watched all officially sanctioned Air Force Internet points-of-presence. (Like any large organization, the AFCERT struggled to deal with local base commanders, or “management,” who bypassed authorized Internet connections by installing their own Internet links.) In 1998 the AFCERT added the Wheel Group’s NetRanger sensors to its toolbox, using them at the request of Central Command to monitor its forward locations in the Middle East.

The AFCERT implemented network security monitoring through products, people, and processes. ASIM was the tool used to generate indications and warnings. AFCERT analysts worked in real-time or batch cells, either reviewing near-real-time alerts or daily session records. Both teams had access to full content or transcript data collected by ASIM for certain high-value services, such as Telnet, rlogin, FTP, HTTP, and other protocols. Analysts escalated evidence of suspected intrusions to the Incident Response Team (IRT), which validated and investigated intrusions. After the Melissa virus hit in March 1999, the AFCERT formed a dedicated virus team to specifically handle malware outbreaks.

In late 2000, Ball Aerospace & Technologies Corporation (BATC) asked Robert “Bamm” Visscher and myself to help transition intrusion detection techniques to the commercial sector. Bamm and I had worked with Larry Shrader in the AFCERT, and we set about creating an NSM operation from scratch. Working on a tight budget, and realizing available commercial IDS products didn’t suit our needs, Bamm developed the Snort Personal Real-time Event GUI (SPREG).

SPREG began its life as a Tcl/Tk program to watch attacks on Bamm’s cable modem connection. As I trained analysts to take on 24 by 7 monitoring duties, Bamm refined SPREG to meet our NSM needs. SPREG relied on Snort for its alert and full content data. John Curry, acting as a consultant, wrote code to collect session data. All three elements were integrated, and by the spring of 2001 BATC offered the first true commercial NSM operation to nongovernment customers. Our 12 analysts interpreted alert, session, and full content data to discover intruders.

In June 2001 I “hacked” a copy of Congressman Lamar Smith’s Web page while Bamm demonstrated our monitoring capability. On July 13, 2001, one of our analysts, LeRoy Crooks, detected the Code Red worm -- six days before it struck the general Internet population. I posted his findings to the SecurityFocus Incidents list on July 15, 2001.

In April 2002, I left BATC to become a consultant with Foundstone. While performing incident response duties I employed emergency NSM to investigate intrusions against several Fortune 100 companies. I began using Argus to collect session data because I no longer had access to the proprietary code BATC bought to collect session data. I began teaching NSM principles to students of Foundstone’s “Incident Response” and “Ultimate Hacking” classes. I also taught NSM to two sessions’ worth of SANS intrusion detection track attendees who responded to my request to abandon the formal material in favor of something more relevant.

On December 4, 2002, Bamm and I presented a Webcast for titled “Network Security Monitoring” ( This presentation offered the first formal definition of NSM as “the collection, analysis, and escalation of indications and warnings (I&W) to detect and respond to intrusions.” At the time I was only theorizing about the use of statistical information and limited NSM to event, session, and full content data. (I began using the term “alert” rather than “event” data when writing this book in fall 2003.)

In late 2002 Bamm began work on an open source NSM product called the Snort GUI for Lamerz (SGUIL). (Sguil’s name was born in an IRC session and was not designed with marketing in mind!) Bamm registered and announced Sguil’s initial availability in January 2003. At the time the most popular open source GUI for Snort was ACID. Throughout 2003 Sguil gained momentum, and it appeared in a second NSM Webcast on August 21, 2003. During 2003 the fourth edition of Hacking Exposed was published. It featured a case study I wrote, which included the NSM definition and this nod to the “father of NSM”:

“Inspired in name by Todd Heberlein’s ‘Network Security Monitor,’ NSM is an operational model based on the Air Force’s signals intelligence collection methods. NSM integrates IDS products, which generate alerts; people, who interpret indications and warning; and processes, which guide the escalation of validated events to decision makers."

I'd like to add a few more points to that original script. First, in 1999-2000, I remember using the AFCERT's Common Intrusion Detection (CID) Java console to right-click and call Ethereal to decode Libpcap data for alerts or sessions of interest. The Libpcap data was collected by our ASIM (Automated Security Incident Measurement) sensors independent of the alerts or sessions. This year you are going to see IDS/IPS vendors tying into network forensic appliance application programming interfaces to do this same trick, only eight years later.

I may try to add to this as I remember more details. Any old Air Force guys out there with memories to add, please feel free to leave comments. Thank you.


John Ward said…
(ahem) How about super programmer and Business Intelligence blogger John Ward was one of your original 12 analysts, and without him life would have been unbearable at the BATC operations ;)
Anonymous said…
An don't forget about the year of NFAT:
Anonymous said…
So would you be mad if I told you that AFCERT is ditching ASIM and going with an IDS approach?
To the extent the Air Force is not going to be performing NSM (product is irrelevant), I am disappointed. Right now it sounds like the Coast Guard is the only military CERT doing NSM.
Anonymous said…
This comment has been removed by a blog administrator.
d said…
The AFCERT is not "ditching" ASIM. The platform is evolving to still be the best at what it does. The CITS Block 30 program uses COTS hardware for the monitoring capabilities, but ASIM is being transformed and redeployed within Block 30 as it has capabilities that no commercial vendor has fielded yet. CIDD, however, is being replaced by ArcSight.

Also, I'll point Larry to your site to note that you misspelled his last name ;)
Hi Dan,

Woops, Schrader. Sorry about that.

Does the "new" ASIM log session data and full content? From what I know, the answer is no...
d said…
ASIM still records. It's replacement, the much ballyhooed IOP, does not - to the chagrin of all the folks that pushed for it.

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