Author Archives: Marcus J. Ranum

About Marcus J. Ranum

Marcus J. Ranum, CSO at Tenable Network Security, Inc., is a world-renowned expert on security system design and implementation. He has been involved in every level of operations of a security product business, from developer, to founder and CEO.

The Best Defense Is a Strong Defense. Never Fight a Land War in Cyberspace.

Summary: Why defense experts obsess about the relative advantages of different military hardware (e.g., the A-10 vs the F-35), the US has unleashed the tools of cyberwar on Iran. We can expect more in the future, begun by friends and foes. So let’s learn the rules. Today Marcus Ranum explains the nature of attack and defense in cyberwar, and the advantages of each.  {@nd of 2 posts today.}

Cyber Warriors

Introduction

My 2014 presentation “Never Fight a Land War in Cyberspace” compared key elements of warfare in the real world with warfare in cyberspace, exploring the interchangeability of tactics and strategy in those domains. I expected that “cyberwar” would have similar underlying principles as regular war, but found that “cyberwar” bears no resemblance to warfare at all — tactically or strategically. Of course it fits in the overall grand strategy of conflct and power, but our tendency to reason by analogy breaks down quickly here.

In this series I will lift some of the main themes from that presentation and give them the more detailed explanation they deserve.

I will use two terms as shorthand.

Cyberwar“, which I do not think is a real thing, as shorthand for “conflict in cyberspace” — which I consider real. This series continues my attempt to explain why “cyberwar” is not a useful concept; unfortunately, the term has taken on a life of its own. Caveat Emptor.

Topological warfare” as shorthand for the idea of warfare that is bound to a real-world existence. The real-world-ness of topological warfare is the basis for what we know as military strategy and tactics; it’s an environment in which armies have to eat and cannot move at light speed, etc. The topological nature of warfare deeply penetrates virtually all of our thinking about strategy and tactics.

“The Best Defense is a Strong Offense”

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The horror of cyberspace: we can’t easily identify our attackers.

Summary: In this last of Marcus Ranum’s 2 posts about identifying cyber-attackers, he explains why the usual methods we read in the news are quite fallible — no matter how confidently they’re stated. Our difficulty with this is a common if scary aspect of modern warfare and crime.  {2nd of 2 posts today.}

Attribution Is Hard - Part 2

Attribution is Hard, Part 2

By Marcus Ranum, Senior Strategist at Tenable Network Security

This article originally appeared on the Tenable Blog.
Reposted with their generous permission.

Yesterday’s part 1 described a classic hacking incident and discussed the challenges of establishing attribution. Today I explain what weak attribution is, and I conclude the discussion on the four requirements of establishing attribution.

Yesterday’s cliff hanger probably left you wondering what I mean by “weak attribution.” There are several forms of weak attribution that warrant discussion.

Attribution by tools

The first form of weak attribution is an argument based on tools used, if those tools are available in the wild to security researchers. Just because a tool is available and used by an attacker doesn’t mean that any other frequent user of the tool is your current perpetrator. There are plenty of hacking tools available for repurposing by other attackers. I hate to sound like a cynic, but apparently some people haven’t yet realized that there are security researchers who play both sides of the game-board; if I wanted to go rogue, I could assemble a state-of-the-art set of custom “state-sponsored” quality malware in about a week.

Tools are clues, not fingerprints.

Attribution by guessing about cui bono

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How do we identify our attackers in cyberspace?

Summary: The news overflows with confident identification of cyberattackers. Today we have an account of hacking from a defender’s perspective, explaining the difficulty of attribution, written by our co-author Marcus Ranum. After reading this, you’ll regard the news about these things more skeptically. {2nd of 2 posts today.}

Attribution Is Hard - Part 1

By Marcus Ranum, Senior Strategist at Tenable Network Security

This article originally appeared on the Tenable Blog.
Reposted with their generous permission.

In 1995 I landed my first independent consulting project: an incident response for an important financial institution in New York City. That experience has informed my attitude about attribution ever since, because it was one of the rare incidents I’ve ever been involved in when we actually learned the identity and location of the attacker with a high degree of certainty.

The attacker was accessing an X.25 connection to the institution, had guessed an account/password pair on one of the Unix hosts, logged in and began looking around. He was first detected by one of the system administrators who noticed something unusual: a service account that normally didn’t log in was logged in, running the telnet command. An incident response team was assembled and we started charting out what was going on, what the attacker was doing, and when the break-in had occurred.

The financial institution was extremely lucky that the system administrator was so observant: the attack was discovered within the first 3 days of the initial break-in. As shown in this animation:

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