Entries Tagged "denial of service"

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China's Great Cannon

Citizen Lab has issued a report on China’s “Great Cannon” attack tool, used in the recent DDoS attack against GitHub.

We show that, while the attack infrastructure is co-located with the Great Firewall, the attack was carried out by a separate offensive system, with different capabilities and design, that we term the “Great Cannon.” The Great Cannon is not simply an extension of the Great Firewall, but a distinct attack tool that hijacks traffic to (or presumably from) individual IP addresses, and can arbitrarily replace unencrypted content as a man-in-the-middle.

The operational deployment of the Great Cannon represents a significant escalation in state-level information control: the normalization of widespread use of an attack tool to enforce censorship by weaponizing users. Specifically, the Cannon manipulates the traffic of “bystander” systems outside China, silently programming their browsers to create a massive DDoS attack. While employed for a highly visible attack in this case, the Great Cannon clearly has the capability for use in a manner similar to the NSA’s QUANTUM system, affording China the opportunity to deliver exploits targeting any foreign computer that communicates with any China-based website not fully utilizing HTTPS.

It’s kind of hard for the US to complain about this kind of thing, since we do it too.

More stories. Hacker News thread.

Posted on April 13, 2015 at 9:12 AM • View Comments

Attributing the Sony Attack

No one has admitted taking down North Korea’s Internet. It could have been an act of retaliation by the US government, but it could just as well have been an ordinary DDoS attack. The follow-on attack against Sony PlayStation definitely seems to be the work of hackers unaffiliated with a government.

Not knowing who did what isn’t new. It’s called the “attribution problem,” and it plagues Internet security. But as governments increasingly get involved in cyberspace attacks, it has policy implications as well. Last year, I wrote:

Ordinarily, you could determine who the attacker was by the weaponry. When you saw a tank driving down your street, you knew the military was involved because only the military could afford tanks. Cyberspace is different. In cyberspace, technology is broadly spreading its capability, and everyone is using the same weaponry: hackers, criminals, politically motivated hacktivists, national spies, militaries, even the potential cyberterrorist. They are all exploiting the same vulnerabilities, using the same sort of hacking tools, engaging in the same attack tactics, and leaving the same traces behind. They all eavesdrop or steal data. They all engage in denial-of-service attacks. They all probe cyberdefences and do their best to cover their tracks.

Despite this, knowing the attacker is vitally important. As members of society, we have several different types of organizations that can defend us from an attack. We can call the police or the military. We can call on our national anti-terrorist agency and our corporate lawyers. Or we can defend ourselves with a variety of commercial products and services. Depending on the situation, all of these are reasonable choices.

The legal regime in which any defense operates depends on two things: who is attacking you and why. Unfortunately, when you are being attacked in cyberspace, the two things you often do not know are who is attacking you and why. It is not that everything can be defined as cyberwar; it is that we are increasingly seeing warlike tactics used in broader cyberconflicts. This makes defence and national cyberdefence policy difficult.

In 2007, the Israeli Air Force bombed and destroyed the al-Kibar nuclear facility in Syria. The Syrian government immediately knew who did it, because airplanes are hard to disguise. In 2010, the US and Israel jointly damaged Iran’s Natanz nuclear facility. But this time they used a cyberweapon, Stuxnet, and no one knew who did it until details were leaked years later. China routinely denies its cyberespionage activities. And a 2009 cyberattack against the United States and South Korea was blamed on North Korea even though it may have originated from either London or Miami.

When it’s possible to identify the origins of cyberattacks­—like forensic experts were able to do with many of the Chinese attacks against US networks­—it’s as a result of months of detailed analysis and investigation. That kind of time frame doesn’t help at the moment of attack, when you have to decide within milliseconds how your network is going to react and within days how your country is going to react. This, in part, explains the relative disarray within the Obama administration over what to do about North Korea. Officials in the US government and international institutions simply don’t have the legal or even the conceptual framework to deal with these types of scenarios.

The blurring of lines between individual actors and national governments has been happening more and more in cyberspace. What has been called the first cyberwar, Russia vs. Estonia in 2007, was partly the work of a 20-year-old ethnic Russian living in Tallinn, and partly the work of a pro-Kremlin youth group associated with the Russian government. Many of the Chinese hackers targeting Western networks seem to be unaffiliated with the Chinese government. And in 2011, the hacker group Anonymous threatened NATO.

It’s a strange future we live in when we can’t tell the difference between random hackers and major governments, or when those same random hackers can credibly threaten international military organizations.

This is why people around the world should care about the Sony hack. In this future, we’re going to see an even greater blurring of traditional lines between police, military, and private actions as technology broadly distributes attack capabilities across a variety of actors. This attribution difficulty is here to stay, at least for the foreseeable future.

If North Korea is responsible for the cyberattack, how is the situation different than a North Korean agent breaking into Sony’s office, photocopying a lot of papers, and making them available to the public? Is Chinese corporate espionage a problem for governments to solve, or should we let corporations defend themselves? Should the National Security Agency defend US corporate networks, or only US military networks? How much should we allow organizations like the NSA to insist that we trust them without proof when they claim to have classified evidence that they don’t want to disclose? How should we react to one government imposing sanctions on another based on this secret evidence? More importantly, when we don’t know who is launching an attack or why, who is in charge of the response and under what legal system should those in charge operate?

We need to figure all of this out. We need national guidelines to determine when the military should get involved and when it’s a police matter, as well as what sorts of proportional responses are available in each instance. We need international agreements defining what counts as cyberwar and what does not. And, most of all right now, we need to tone down all the cyberwar rhetoric. Breaking into the offices of a company and photocopying their paperwork is not an act of war, no matter who did it. Neither is doing the same thing over the Internet. Let’s save the big words for when it matters.

This essay previously appeared on TheAtlantic.com.

Jack Goldsmith responded to this essay.

Posted on January 7, 2015 at 11:16 AM • View Comments

DDoSing a Cell Phone Network

Interesting research:

Abstract: The HLR/AuC is considered to be one of the most important network elements of a 3G network. It can serve up to five million subscribers and at least one transaction with HLR/AuC is required for every single phone call or data session. This paper presents experimental results and observations that can be exploited to perform a novel distributed denial of service attack in 3G networks that targets the availability of the HLR/AuC. More specifically, first we present an experiment in which we identified and proved some zero-day vulnerabilities of the 3G network that can be exploited by malicious actors to mount various attacks. For the purpose of our experiment, we have used off-the-shelf infrastructure and software, without any specialized modification. Based on the observations of the experiment, we reveal an Advanced Persistent Threat (APT) in 3G networks that aims to flood an HLR/AuC of a mobile operator. We also prove that the discovered APT can be performed in a trivial manner using commodity hardware and software, which is widely and affordably available.

The attack involves cloning SIM cards, then making multiple calls from different handsets in different locations with the same SIM card. This confuses the network into thinking that the same phone is in multiple places at once.

Note that this has not been tested in the field, but there seems no reason why it wouldn’t work.

There’s a lot of insecurity in the fact that cell phones and towers largely trust each other. The NSA and FBI use that fact for eavesdropping, and here it’s used for a denial-of-service attack.

Posted on February 26, 2014 at 6:55 AM • View Comments

DDOS Attacks Using NTP

This is new:

The NTP method first began to appear late last year. To bring down a server such as one running “League of Legends,” the attackers trick NTP servers into thinking they’ve been queried by the “League of Legends” server.

The NTP servers, thinking they’re responding to a legitimate query, message the “League of Legends” server, overloading it with as many as 100 gigabits per second (Gbps). That’s large even for a DDoS attack.

In this way, one small request to an NTP server can generate an enormous response capable of taking down even high-capacity websites.

Posted on January 20, 2014 at 6:18 AM • View Comments

DDOS as Civil Disobedience

For a while now, I have been thinking about what civil disobedience looks like in the Internet Age. Certainly DDOS attacks, and politically motivated hacking in general, is a part of that. This is one of the reasons I found Molly Sauter’s recent thesis, “Distributed Denial of Service Actions and the Challenge of Civil Disobedience on the Internet,” so interesting:

Abstract: This thesis examines the history, development, theory, and practice of distributed denial of service actions as a tactic of political activism. DDOS actions have been used in online political activism since the early 1990s, though the tactic has recently attracted significant public attention with the actions of Anonymous and Operation Payback in December 2010. Guiding this work is the overarching question of how civil disobedience and disruptive activism can be practiced in the current online space. The internet acts as a vital arena of communication, self expression, and interpersonal organizing. When there is a message to convey, words to get out, people to organize, many will turn to the internet as the zone of that activity. Online, people sign petitions, investigate stories and rumors, amplify links and videos, donate money, and show their support for causes in a variety of ways. But as familiar and widely accepted activist tools—petitions, fundraisers, mass letter-writing, call-in campaigns and others—find equivalent practices in the online space, is there also room for the tactics of disruption and civil disobedience that are equally familiar from the realm of street marches, occupations, and sit-ins? This thesis grounds activist DDOS historically, focusing on early deployments of the tactic as well as modern instances to trace its development over time, both in theory and in practice. Through that examination, as well as tool design and development, participant identity, and state and corporate responses, this thesis presents an account of the development and current state of activist DDOS actions. It ends by presenting an analytical framework for the analysis of activist DDOS actions.

One of the problems with the legal system is that it doesn’t make any differentiation between civil disobedience and “normal” criminal activity on the Internet, though it does in the real world.

Posted on May 22, 2013 at 6:24 AM • View Comments

Security Externalities and DDOS Attacks

Ed Felten has a really good blog post about the externalities that the recent Spamhaus DDOS attack exploited:

The attackers’ goal was to flood Spamhaus or its network providers with Internet traffic, to overwhelm their capacity to handle incoming network packets. The main technical problem faced by a DoS attacker is how to amplify the attacker’s traffic-sending capacity, so that the amount of traffic arriving at the target is much greater than the attacker can send himself. To do this, the attacker typically tries to induce many computers around the Internet to send large amounts of traffic to the target.

The first stage of the attack involved the use of a botnet, consisting of a large number of software agents surreptitiously installed on the computers of ordinary users. These bots were commanded to send attack traffic. Notice how this amplifies the attacker’s traffic-sending capability: by sending a few commands to the botnet, the attacker can induce the botnet to send large amounts of attack traffic. This step exploits our first externality: the owners of the bot-infected computers might have done more to prevent the infection, but the harm from this kind of attack activity falls onto strangers, so the computer owners had a reduced incentive to prevent it.

Rather than having the bots send traffic directly to Spamhaus, the attackers used another step to further amplify the volume of traffic. They had the bots send queries to DNS proxies across the Internet (which answer questions about how machine names like www.freedom-to-tinker.com related to IP addresses like 209.20.73.44). This amplifies traffic because the bots can send a small query that elicits a large response message from the proxy.

Here is our second externality: the existence of open DNS proxies that will respond to requests from anywhere on the Internet. Many organizations run DNS proxies for use by their own people. A well-managed DNS proxy is supposed to check that requests are coming from within the same organization; but many proxies fail to check this—they’re “open” and will respond to requests from anywhere. This can lead to trouble, but the resulting harm falls mostly on people outside the organization (e.g. Spamhaus) so there isn’t much incentive to take even simple steps to prevent it.

To complete the attack, the DNS requests were sent with false return addresses, saying that the queries had come from Spamhaus—which causes the DNS proxies to direct their large response messages to Spamhaus.

Here is our third externality: the failure to detect packets with forged return addresses. When a packet with a false return address is injected, it’s fairly easy for the originating network to detect this: if a packet comes from inside your organization, but it has a return address that is outside your organization, then the return address must be forged and the packet should be discarded. But many networks fail to check this. This causes harm but—you guessed it—the harm falls outside the organization, so there isn’t much incentive to check. And indeed, this kind of packet filtering has long been considered a best practice but many networks still fail to do it.

I’ve been writing about security externalities for years. They’re often much harder to solve than technical problems.

By the way, a lot of the hype surrounding this attack was media manipulation.

Posted on April 10, 2013 at 12:46 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.