[ISN] Annual hacking game teaches security lessons
isn at c4i.org
Fri Aug 5 01:04:52 EDT 2005
LAS VEGAS -- The weekend-long Capture the Flag tournament stressed
code auditing as a measure of hacking skill this year, a move that
emphasized more real-world skills, but not without controversy.
The annual Capture the Flag tournament at DEF CON has always attracted
participants from a variety of background, looking to try their hands
at online attack and defense. Under a new set of organizers this year,
the game pitted teams and individuals against each other to find and
exploit vulnerabilities in their opponents' systems to score points.
The game, dubbed "WarGamez" this year, put more emphasis on real-world
skills compared to previous years, said Giovanni Vigna, associate
professor of computer science at the University of California at Santa
Barbara and the leader of team Shellphish, which won the event.
"The game required skills that are also required by both security
researchers and hackers, such as ability to analyze attack vectors,
understanding and automating attacks, finding new, unpredictable ways
to exploit things," Vigna said. "It's about analyzing the security
posture of a system that is given to you and about which you initially
The latest incarnation of the game--run by a group of security
professionals who asked to only be identified by their group name,
Kenshoto--attracted students, military computer experts, security
professionals and hobbyist hackers. For the teams, the controversy
surrounding security researcher Michael Lynn's outing of a
high-profile vulnerability in Cisco Systems' routers, mattered little.
Finding vulnerabilities in each other's servers became the focus of
In previous years, the game allowed each side to run their own server,
and required that certain services be available. This year, the
organizers ran a central server on which each team's virtual server
The move was not without controversy, however, as it removed from the
contest any teams that concentrated on defending their systems by
using a specialized operating system, said Crispin Cowan, director of
software engineering for Novell's Linux division, SUSE.
"Prior games involved both attackers and defenders working on the
problem, but because Kenshoto took total control of the reference
servers to be defended, there is very little defense that can be
deployed," Cowan said. "Their scoring system also made defense
essentially worthless other than to deny other teams points."
Cowan competed for several years as the leader of a team fielded by
secure Linux operating system vendor Immunix, which was bought by
Novell in May. Porting services over to its security-enhanced
operating system became a signature strategy of the team.
The Capture the Flag game is suppose to measure security researchers
and hackers abilities to attack and defend systems, said one of the
organizers, not necessarily be a test of products.
"We did intentionally de-emphasize defense, because it is a hacking
competition, after all," said the organizer. By agreement, the group
that ran the game adopted the name Kenshoto and would only speak
anonymously. "However, defensive skills were tested."
Some teams had success deploying Tripwire, a data-integrity checker
that can find changed files, and monitoring traffic with an intrusion
detection system, he said. A knowledgeable defender could also
lockdown the systems, further hardening them. Moreover, the amount of
uptime for each service directly affected the score, so defending the
applications that ran the services became a key strategy, the
In the end, however, the game focused on finding and exploiting
"What it takes to be an elite hacker is to find vulnerabilities in
custom software," said the Kenshoto member. "It is not code auditing
per se. They have to reverse engineer, and we have made it difficult
to reverse engineer."
The Kenshoto group ran all the teams' virtual servers on a single
machine using a technique known as "jailing," which limits each team
or individual to separate directories on the master system. The
computer ran the FreeBSD operating system and utilities and services
were written in Python, Java and C. The group also ran an in-game
auction site known as eDay.
Each team's authentication token, or totem, was placed on the bottom
of a can of Tab, which the team was expected to guard.
While a few individuals and teams used the eDay auction site, most of
the deals for items were done behind the scene, according to one
member of Kenshoto. One team's can of Tab, which held the team's
secret code on the bottom, went for 101 beers, the organizer said.
The teams each sought to score points by keeping services running,
stealing or overwriting digital tokens on each server, and producing
advisories with working exploit code. Rooting the main Kenshoto
mainframe would earn massive points, according to the rules, but a
failed attempt would penalize the team "back into the stone age."
Auditing did play a big role in the game's strategy, said the Kenshoto
organizers, because finding flaws is a major factor in attack and
defense in the real online world.
"The auditing people did as part of the game was similar to the job of
anyone trying to find risks in third party software, be it a black hat
or someone trying to determine whether third-party software is safe to
integrate with an existing system," said one organizer.
Notable differences, however, include the time pressure, the fact that
participants not only had to find a vulnerability but exploit the
flaw, and that the teams did not have access to any source code.
The winning strategy balanced finding flaws with hardening the systems
services, said Vigna of the winning team Shellphish.
"On the defense side, we had people responsible for monitoring--both
manually and using automated tools--incoming traffic and running
processes to find out how we were attacked," he said. "We also had
people that make sure that our services were up an running ...
Finally, we had people who would choose a service and try to find
In the end, however, Novell's Cowan remained unconvinced that focusing
on finding flaws in arbitrary systems had much to do with real-world
"The Kenshoto game is not invalid, it just focuses specifically on
code auditing to the exclusion of all else," Cowan said. "If
Kenshoto's game of this year persists, then ... anyone else with any
significant interest in defense (will not participate), and the game
will be entirely dominated by code analysis players."
Correction: The original article incorrectly identified the
programming languages used to write the applications for the Capture
the Flag game. The languages are Python, Java, and C.
More information about the ISN