Robert Graham

Author Archives: Robert Graham

Slowloris all the things

At DEFCON, some researchers are going to announce a Slowloris-type exploit for SMB -- SMBloris. I thought I'd write up some comments.


The original Slowloris from several years creates a ton of connections to a web server, but only sends partial headers. The server allocates a large amount of memory to handle the requests, expecting to free that memory soon when the requests are completed. But the requests are never completed, so the memory remains tied up indefinitely. Moreover, this also consumes a lot of CPU resources -- every time Slowloris dribbles a few more bytes on the TCP connection is forces the CPU to walk through a lot of data structures to handle those bytes.

The thing about Slowloris is that it's not specific to HTTP. It's a principle that affects pretty much every service that listens on the Internet. For example, on Linux servers running NFS, you can exploit the RPC fragmentation feature in order to force the server to allocate all the memory in a box waiting for fragments that never arrive.

SMBloris does the same thing for SMB. It's an easy attack to carry out in general, the only question is how much resources are required Continue reading

Defending anti-netneutrality arguments

Last week, activists proclaimed a "NetNeutrality Day", trying to convince the FCC to regulate NetNeutrality. As a libertarian, I tweeted many reasons why NetNeutrality is stupid. NetNeutrality is exactly the sort of government regulation Libertarians hate most. Somebody tweeted the following challenge, which I thought I'd address here.


The links point to two separate cases.
  • the Comcast BitTorrent throttling case
  • a lawsuit against Time Warning for poor service
The tone of the tweet suggests that my anti-NetNeutrality stance cannot be defended in light of these cases. But of course this is wrong. The short answers are:

  • the Comcast BitTorrent throttling benefits customers
  • poor service has nothing to do with NetNeutrality

The long answers are below.

The Comcast BitTorrent Throttling

The presumption is that any sort of packet-filtering is automatically evil, and against the customer's interests. That's not true.

Take GoGoInflight's internet service for airplanes. They block access to video sites like NetFlix. That's because they often have as little as 1-mbps for the entire plane, which is enough to support many people checking email and browsing Continue reading

Burner laptops for DEF CON

Hacker summer camp (Defcon, Blackhat, BSidesLV) is upon us, so I thought I'd write up some quick notes about bringing a "burner" laptop. Chrome is your best choice in terms of security, but I need Windows/Linux tools, so I got a Windows laptop.

I chose the Asus e200ha for $199 from Amazon with free (and fast) shipping. There are similar notebooks with roughly the same hardware and price from other manufacturers (HP, Dell, etc.), so I'm not sure how this compares against those other ones. However, it fits my needs as a "burner" laptop, namely:
  • cheap
  • lasts 10 hours easily on battery
  • weighs 2.2 pounds (1 kilogram)
  • 11.6 inch and thin
Some other specs are:
  • 4 gigs of RAM
  • 32 gigs of eMMC flash memory
  • quad core 1.44 GHz Intel Atom CPU
  • Windows 10
  • free Microsoft Office 365 for one year
  • good, large keyboard
  • good, large touchpad
  • USB 3.0
  • microSD
  • WiFi ac
  • no fans, completely silent
There are compromises, of course.
  • The Atom CPU is slow, thought it's only noticeable when churning through heavy webpages. Adblocking addons or Brave are a necessity. Most things are usably fast, such as using Microsoft Word.
  • Crappy sound and Continue reading

Yet more reasons to disagree with experts on nPetya

In WW II, they looked at planes returning from bombing missions that were shot full of holes. Their natural conclusion was to add more armor to the sections that were damaged, to protect them in the future. But wait, said the statisticians. The original damage is likely spread evenly across the plane. Damage on returning planes indicates where they could damage and still return. The undamaged areas are where they were hit and couldn't return. Thus, it's the undamaged areas you need to protect.

This is called survivorship bias.

Many experts are making the same mistake with regards to the nPetya ransomware. 

I hate to point this out, because they are all experts I admire and respect, especially @MalwareJake, but it's still an error. An example is this tweet:


The context of this tweet is the discussion of why nPetya was well written with regards to spreading, but full of bugs with regards to collecting on the ransom. The conclusion therefore that it wasn't intended to be ransomware, but was intended Continue reading

NonPetya: no evidence it was a “smokescreen”

Many well-regarded experts claim that the not-Petya ransomware wasn't "ransomware" at all, but a "wiper" whose goal was to destroy files, without any intent at letting victims recover their files. I want to point out that there is no real evidence of this.


Certainly, things look suspicious. For one thing, it certainly targeted the Ukraine. For another thing, it made several mistakes that prevent them from ever decrypting drives. Their email account was shutdown, and it corrupts the boot sector.

But these things aren't evidence, they are problems. They are things needing explanation, not things that support our preferred conspiracy theory.

The simplest, Occam's Razor explanation explanation is that they were simple mistakes. Such mistakes are common among ransomware. We think of virus writers as professional software developers who thoroughly test their code. Decades of evidence show the opposite, that such software is of poor quality with shockingly bad bugs.

It's true that effectively, nPetya is a wiper. Matthieu Suiche‏ does a great job describing one flaw that prevents it working. @hasherezade does a great job explaining another flaw.  But best explanation isn't that this is intentional. Even if these bugs didn't exist, it'd still be a wiper if the Continue reading

A kindly lesson for you non-techies about encryption

The following tweets need to be debunked:



The answer to John Schindler's question is:
every expert in cryptography doesn't know this
Oh, sure, you can find fringe wacko who also knows crypto that agrees with you but all the sane members of the security community will not.


Telegram is not trustworthy because it's closed-source. We can't see how it works. We don't know if they've made accidental mistakes that can be hacked. We don't know if they've been bribed by the NSA or Russia to put backdoors in their program. In contrast, PGP and Signal are open-source. We can read exactly what the software does. Indeed, thousands of people have been reviewing their software looking for mistakes and backdoors.

Encryption works. Neither the NSA nor the Russians can break properly encrypted content. There's no such thing as "military grade" encryption that is better than consumer grade. There's only encryption that nobody can hack vs. encryption that your neighbor's teenage kid can easily hack. There's essentially nothing in between. Those scenes in TV/movies about breaking encryption is as realistic as sound in space: good for dramatic presentation, but not how things work in the real world.

In particular, end-to-end encryption works. Continue reading

Notes on open-sourcing abandoned code

Some people want a law that compels companies to release their source code for "abandoned software", in the name of cybersecurity, so that customers who bought it can continue to patch bugs long after the seller has stopped supporting the product. This is a bad policy, for a number of reasons.


Code is Speech

First of all, code is speech. That was the argument why Phil Zimmerman could print the source code to PGP in a book, ship it overseas, and then have somebody scan the code back into a computer. Compelled speech is a violation of free speech. That was one of the arguments in the Apple vs. FBI case, where the FBI demanded that Apple write code for them, compelling speech.

Compelling the opening of previously closed source is compelled speech. Sure, demanding new products come with source would be one thing, but going backwards demanding source for products sold before 2017 is quite another thing.

For most people, "rights" are something that only their own side deserves. Whether something deserves the protection of "free speech" depends upon whether the speaker is "us" or the speaker is "them". If it's "them", then you'll find all sorts of reasons Continue reading

More notes on US-CERTs IOCs

Yet another Russian attack against the power grid, and yet more bad IOCs from the DHS US-CERT.

IOCs are "indicators of compromise", things you can look for in order to order to see if you, too, have been hacked by the same perpetrators. There are several types of IOCs, ranging from the highly specific to the uselessly generic.

A uselessly generic IOC would be like trying to identify bank robbers by the fact that their getaway car was "white" in color. It's worth documenting, so that if the police ever show up in a suspected cabin in the woods, they can note that there's a "white" car parked in front.

But if you work bank security, that doesn't mean you should be on the lookout for "white" cars. That would be silly.

This is what happens with US-CERT's IOCs. They list some potentially useful things, but they also list a lot of junk that waste's people's times, with little ability to distinguish between the useful and the useless.

An example: a few months ago was the GRIZZLEYBEAR report published by US-CERT. Among other things, it listed IP addresses used by hackers. There was no description which would be useful IP Continue reading

What about other leaked printed documents?

So nat-sec pundit/expert Marci Wheeler (@emptywheel) asks about those DIOG docs leaked last year. They were leaked in printed form, then scanned in an published by The Intercept. Did they have these nasty yellow dots that track the source? If not, why not?

The answer is that the scanned images of the DIOG doc don't have dots. I don't know why. One reason might be that the scanner didn't pick them up, as it's much lower quality than the scanner for the Russian hacking docs. Another reason is that the printer used my not have printed them -- while most printers do print such dots, some printers don't. A third possibility is that somebody used a tool to strip the dots from scanned images. I don't think such a tool exists, but it wouldn't be hard to write.

Scanner quality

The printed docs are here. They are full of whitespace where it should be easy to see these dots, but they appear not to be there. If we reverse the image, we see something like the following from the first page of the DIOG doc:


Compare this to the first page of the Russian hacking doc which shows Continue reading

How The Intercept Outed Reality Winner

Today, The Intercept released documents on election tampering from an NSA leaker. Later, the arrest warrant request for an NSA contractor named "Reality Winner" was published, showing how they tracked her down because she had printed out the documents and sent them to The Intercept. The document posted by the Intercept isn't the original PDF file, but a PDF containing the pictures of the printed version that was then later scanned in.

The problem is that most new printers print nearly invisibly yellow dots that track down exactly when and where documents, any document, is printed. Because the NSA logs all printing jobs on its printers, it can use this to match up precisely who printed the document.

In this post, I show how.

You can download the document from the original article here. You can then open it in a PDF viewer, such as the normal "Preview" app on macOS. Zoom into some whitespace on the document, and take a screenshot of this. On macOS, hit [Command-Shift-3] to take a screenshot of a window. There are yellow dots in this image, but you can barely see them, especially if your screen is dirty.

We need to highlight the yellow Continue reading

Some non-lessons from WannaCry

This piece by Bruce Schneier needs debunking. I thought I'd list the things wrong with it.

The NSA 0day debate

Schneier's description of the problem is deceptive:
When the US government discovers a vulnerability in a piece of software, however, it decides between two competing equities. It can keep it secret and use it offensively, to gather foreign intelligence, help execute search warrants, or deliver malware. Or it can alert the software vendor and see that the vulnerability is patched, protecting the country -- and, for that matter, the world -- from similar attacks by foreign governments and cybercriminals. It's an either-or choice.
The government doesn't "discover" vulnerabilities accidentally. Instead, when the NSA has a need for something specific, it acquires the 0day, either through internal research or (more often) buying from independent researchers.

The value of something is what you are willing to pay for it. If the NSA comes across a vulnerability accidentally, then the value to them is nearly zero. Obviously such vulns should be disclosed and fixed. Conversely, if the NSA is willing to pay $1 million to acquire a specific vuln for imminent use against a target, the offensive value is much greater than the Continue reading

How to track that annoying pop-up

In a recent update to their Office suite on Windows, Microsoft made a mistake where every hour, for a fraction of a second,  a black window pops up on the screen. This leads many to fear their system has been infected by a virus. I thought I'd document how to track this down.

The short answer is to use Mark Russinovich's "sysinternals.com" tools. He's Windows internals guru at Microsoft and has been maintaining a suite of tools that are critical for Windows system maintenance and security. Copy all the tools from "https://live.sysinternals.com". Also, you can copy with Microsoft Windows Networking (SMB).


Of these tools, what we want is something that looks at "processes". There are several tools that do this, but focus on processes that are currently running. What we want is something that monitors process creation.

The tool for that is "sysmon.exe". It can monitor not only process creation, but a large number of other system events that a techy can use to see what the system has been doing, and if you are infected with a virus.

Sysmon has a fairly complicated configuration file, and if you enabled everything, you'd soon be Continue reading

I want to talk for a moment about tolerance

This post is in response to this Twitter thread. I was going to do a series of tweets in response, but as the number grew, I thought it'd better be done in a blog.


She thinks we are fighting for the rights of Nazis. We aren't -- indeed, the fact that she thinks we are is exactly the problem. They aren't Nazis.

The issue is not about a slippery slope that first Nazi's lose free speech, then other groups start losing their speech as well. The issue is that it's a slippery slope that more and more people get labeled a Nazi. And we are already far down that slope.

The "alt-right" is a diverse group. Like any group. Vilifying the entire alt-right by calling them Nazi's is like lumping all Muslims in with ISIS or Al Qaeda. We really don't have Nazi's in America. Even White Nationalists don't fit the bill. Nazism was about totalitarianism, real desire to exterminate Jews, lebensraum, and Aryan superiority. Sure, some of these people exist, but they are a fringe, even among Continue reading

Houston we have a problem!


Of the many undesirable results of the Space Program is the fetishization of the "mission control center", with it's rows of workstations facing a common central screen. Ever since, anybody with any sort of mission now has a similar control center.

It's a pain for us in the cybersecurity community because every organization wants a "security operations center" laid out the same way. The point of he room isn't to create something that's efficient for working, but one that will impress visitors. The things done to impress customers can often make an already difficult job even more difficult.




I point this out because of the "glowing globe" picture from President Trump's visit to Saudi Arabia. It's supposed to celebrate the opening of the "Global Center for Combating Extremist Ideology" (http://etidal.org). Zoom the camera out a bit, and you can see it's the mission control center from hell.


Manually counting, I see three sides, each with slightly more than 100 workstations/employees, or more than 300 in total. I don't know if they intend all three sections to focus on the same sets of problems, or if they are split into three different tasks (e.g. broadcast TV vs. Continue reading

Some notes on Trump’s cybersecurity Executive Order

President Trump has finally signed an executive order on "cybersecurity". The first draft during his first weeks in power were hilariously ignorant. The current draft, though, is pretty reasonable as such things go. I'm just reading the plain language of the draft as a cybersecurity expert, picking out the bits that interest me. In reality, there's probably all sorts of politics in the background that I'm missing, so I may be wildly off-base.

Holding managers accountable

This is a great idea in theory. But government heads are rarely accountable for anything, so it's hard to see if they'll have the nerve to implement this in practice. When the next breech happens, we'll see if anybody gets fired.


"antiquated and difficult to defend Information Technology"

The government uses laughably old computers sometimes. Forces in government wants to upgrade them. This won't work. Instead of replacing old computers, the budget will simply be used to add new computers. The old computers will still stick around.

"Legacy" is a problem that money can't solve. Programmers know how to build small things, but not big things. Everything starts out small, then becomes big gradually over time through constant small additions. What you have now Continue reading

John Oliver is wrong about Net Neutrality

People keep linking to John Oliver bits. We should stop doing this. This is comedy, but people are confused into thinking Oliver is engaging in rational political debate:


Enlightened people know that reasonable people disagree, that there's two sides to any debate. John Oliver's bit erodes that belief, making one side (your side) sound smart, and the other side sound unreasonable.

The #1 thing you should know about Net Neutrality is that reasonable people disagree. It doesn't mean they are right, only that they are reasonable. They aren't stupid. They aren't shills for the telcom lobby, or confused by the telcom lobby. Indeed, those opposed to Net Neutrality are the tech experts who know how packets are routed, whereas the supporters tend only to be lawyers, academics, and activists. If you think that the anti-NetNeutrality crowd is unreasonable, then you are in a dangerous filter bubble.

Most everything in John Oliver's piece is incorrect.

For example, he says that without Net Neutrality, Comcast can prefer original shows it produces, and slow down competing original shows Continue reading

Hacker dumps, magnet links, and you

In an excellent post pointing out Wikileaks deserves none of the credit given them in the #MacronLeaks, the author erroneously stated that after Archive.org took down the files, that Wikileaks provided links to a second archive. This is not true. Instead, Wikileaks simply pointed to what's known as "magnet links" of the first archive. Understanding magnet links is critical to understanding all these links and dumps, so I thought I'd describe them.

The tl;dr version is this: anything published via BitTorrent has a matching "magnet link" address, and the contents can still be reached via magnet links when the original publisher goes away.


In this case, the leaker uploaded to "archive.org", a popular Internet archiving resource. This website allows you to either download files directly, which is slow, or via peer-to-peer using BitTorrent, which is fast. As you know, BitTorrent works by all the downloaders exchanging pieces with each other, rather getting them from the server. I give you a piece you don't have, in exchange for a piece I don't have.

BitTorrent, though still requires a "torrent" (a ~30k file that lists all the pieces) and a "tracker" (http://bt1.archive.org:6969/announce) that keeps a list Continue reading

Some notes on #MacronLeak

Tonight (Friday May 5 2017) hackers dumped emails (and docs) related to French presidential candidate Emmanuel Macron. He's the anti-Putin candidate running against the pro-Putin Marin Le Pen. I thought I'd write up some notes.


Are they Macron's emails?

No. They are e-mails from members of his staff/supporters, namely Alain Tourret, Pierre Person, Cedric O??, Anne-Christine Lang, and Quentin Lafay.

There are some documents labeled "Macron" which may have been taken from his computer, cloud drive -- his own, or an assistant.


Who done it?

Obviously, everyone assumes that Russian hackers did it, but there's nothing (so far) that points to anybody in particular.

It appears to be the most basic of phishing attacks, which means anyone could've done it, including your neighbor's pimply faced teenager.

Update: Several people [*] have pointed out Trend Micro reporting that Russian/APT28 hackers were targeting Macron back on April 24. Coincidentally, this is also the latest that emails appear in the dump.


What's the hacker's evil plan?

Everyone is proposing theories about the hacker's plan, but the most likely answer is they don't have one. Hacking is opportunistic. They likely targeted everyone in the campaign, and these were the Continue reading

FBI’s Comey dangerous definition of “valid” journalism

The First Amendment, the "freedom of speech" one, does not mention journalists. When it says "freedom of the press" it means the physical printing press. Yes, that does include newspapers, but it also includes anybody else publishing things, such as the famous agitprop pamphlets published by James Otis, John Dickinson, and Thomas Paine. There was no journalistic value to Thomas Paine's Common Sense. The pamphlet argued for abolishing the monarchy and for American independence.

Today in testimony before congress, FBI directory James Comey came out in support of journalism, pointing out that they would not prosecute journalists doing their jobs. But he then modified his statement, describing "valid" journalists as those who in possession of leaks would first check with the government, to avoid publishing anything that would damage national security. It's a power the government has abused in the past to delay or censor leaks. It's specifically why Edward Snowden contacted Glenn Greenwald and Laura Poitras -- he wanted journalists who would not kowtow the government on publishing the leaks.

Comey's testimony today was in regards to prosecuting Assange and Wikileaks. Under the FBI's official "journalist" classification scheme, Wikileaks are not real journalists, but instead publish "intelligence porn" and Continue reading

“Fast and Furious 8: Fate of the Furious”

So "Fast and Furious 8" opened this weekend to world-wide box office totals of $500,000,000. I thought I'd write up some notes on the "hacking" in it. The tl;dr version is this: yes, while the hacking is a bit far fetched, it's actually more realistic than the car chase scenes, such as winning a race with the engine on fire while in reverse.

[SPOILERS]


Car hacking


The most innovative cyber-thing in the movie is the car hacking. In one scene, the hacker takes control of the cars in a parking structure, and makes them rain on to the street. In another scene, the hacker takes control away from drivers, with some jumping out of their moving cars in fear.

How real is this?

Well, today, few cars have a mechanical link between the computer and the steering wheel. No amount of hacking will fix the fact that this component is missing.

With that said, most new cars have features that make hacking possible. I'm not sure, but I'd guess more than half of new cars have internet connections (via the mobile phone network), cameras (for backing up, but also looking forward for lane departure warnings), braking (for emergencies), and acceleration.

Continue reading
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