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DEF CON 29 - Richard Henderson - Old MacDonald Had a Barcode, E I E I CAR

DEF CON 29 - Richard Henderson - Old MacDonald Had a Barcode, E I E I CAR on HackerTube: recommended by 4 Hacker News commenters across 4 separate months, 2021–2026.

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A DEF CON 29 talk by Richard Henderson about encoding the EICAR antivirus test string into QR codes and barcodes and scanning them at real systems. Many systems that do not expect such input misbehave or collapse, including a parking garage system.

Why Hacker News recommends it

HN commenters recommend it as an entertaining demonstration of how scanners and antivirus software fail on unexpected input.

people recommended it
4
separate months
4
strong recommendations
0
discussed on HN
2021–2026
“This guy put the EICAR test string into a barcode and started to scan it on various systems, with rather funny effects.”
— tetha, Apr 2026, in “Claude system prompt bug wastes user money and bricks managed agents”

What HN commenters said

6 Hacker News comments link this video. Each one links back to its thread.

tethaApr 2026Recommends

Do have way too much fun with EICAR: ▶ this video This guy put the EICAR test string into a barcode and started to scan it on various systems, with rather funny effects.

in “Claude system prompt bug wastes user money and bricks managed agents” · View on HN

Full_ClarkJun 2025Recommends

There's a good DEFCON 29 presentation on this topic. ▶ this video If you skip forward to 16m 33s you'll be treated to a lively streak of invective from the passenger of a car whose driver has just confirmed that feeding EICAR to a parking system prevents it from letting any vehicle past the barrier.

in “Nitrogen Triiodide (2016)” · View on HN

jrockwayNov 2023Recommends

None of this seems too terrible to handle. The title of the song can be an empty string, so use *string/Maybe string instead of string to distinguish between unset and "some idiot made the song literally untitled". I am surprised there are no songs that use characters only available in two different character sets, or are the same Chinese character repeated with multiple different writings (Simplified Chinese, Traditional Chinese, Korean, Japanese). I suppose that some people are running into trouble by using CHARACTER VARYING(n) instead of TEXT in their database, but if you pick the most likely database for your local music player, then it doesn't matter. (sqlite doesn't care, basically.) The song that's named after a virus test signature is amusing. I guess encrypt your filenames and database so that the OS can't pry into the details. Since you hopefully didn't write your music player in C, there should be no way that a virus can affect your music player. (While I was researching this post, I found an interesting Defcon talk about what happens when you turn the EICAR virus signature into a QR code and scan it. ▶ this video A lot of stuff breaks! I almost got forced into adding similar breakage. At work we make what is essentially a database, and we got acquired by A Large Company, which had to do a security audit of our software. One of the "security vulnerabilities" in our product was that we don't scan the data in the database for viruses. We pushed back to not do this, becaus

in “Horrible edge cases to consider when dealing with music (2022)” · View on HN

grapescheeseeFeb 2022Recommends

Richard Henderson had a talk at the last Defcon about QR codes. I'd recommended checking it out. Video - ▶ this video PDF of slides - [link]

in “FBI sounds alarm as QR code usage soars” · View on HN

fortran77Mar 2022Cites it

You can shut down all sorts of things with the EICAR string encoded as a QR code. See: [link] and this video ▶ this video where all the gates at a parking garage are rendered inoperable because someone scanned a QR code that encoded EICAR

in “Gas pumps happen to be about as insecure as your typical router” · View on HN

dogleashAug 2021Cites it

>innocuous QR code might automatically download an image Just a few days ago at DEF CON some presenter had been going around with the EICAR test string in a QR code and having fun with all the forced AV hits that can cause. ▶ this video [link]

in “Apple Has Opened the Backdoor to Increased Surveillance and Censorship” · View on HN

Topics & tags

Security & hackingeicarqr codesantivirusdef coninput handling