My university uses prompt injection to catch cheaters • Hacker News Board

Re: My university uses prompt injection to catch cheaters

#11

Post by volemo » Mon, Apr 06, 2026, 9:19 AM UTC

petterroea wrote: post #10

zeroCalories wrote: post #8

Earlier quoted context omitted.

It's pointless. Just an arms race of gimmicks. There's really no option besides making homework all optional, and putting 100% of the grade into in-person exams. I basically don't trust that any new graduate has earned their degree, and won't until schools do what's necessary to crush cheaters.

I agree with you in spirit, but the last meta pre-LLM was that exams were bad at measuring student skill and that students felt more fairly treated when their grade was the result of multiple assignments and projects. I think it's a shame we have move away from that

> exams were bad at measuring student skill

They are. I have a friend who was significantly more smart and thorough in our studies but often get bad scores on exams not being able to concentrate under the pressure.

Re: My university uses prompt injection to catch cheaters

#12

Post by petterroea » Mon, Apr 06, 2026, 9:29 AM UTC

volemo wrote: post #11

petterroea wrote: post #10

Earlier quoted context omitted.

I agree with you in spirit, but the last meta pre-LLM was that exams were bad at measuring student skill and that students felt more fairly treated when their grade was the result of multiple assignments and projects. I think it's a shame we have move away from that

> exams were bad at measuring student skill They are. I have a friend who was significantly more smart and thorough in our studies but often get bad scores on exams not being able to concentrate under the pressure.

Exams also rarely measured skill in the course. Often just a subset. We would often spend the last month of each semester cramming exams instead of studying the curse material because it wasn't that useful.

I rarely felt I got a lot out of courses, but I often felt I would if I got to study it properly

Re: My university uses prompt injection to catch cheaters

#13

Post by chiffaa » Mon, Apr 06, 2026, 9:32 AM UTC

petterroea wrote: post #6

LandenLove wrote: post #4

Prompt injecting homework assignments is a funny idea, but doesn't seem very productive. Either the teacher needs to adjust how they are teaching new concepts or the student needs to ask themself why they are attending college in the first place.

The student is attending college to get a job. Most students don't care about the course. Probably around 50% of students in my year were only in it for the well paying jobs a prestigious degree like that could give them. This has to be part of the threat model for cheating.

I am in my final year of my bachelors in Software Engineering. I was (mostly still am) very interested in both SWE and CS in various angles - I studied a decent bit of PL theory, I tried to get into systems programming, I've built a bunch of "portfolio crud" software and had a short internship in a real company, with all of the above being roughly equally interesting to me. All this is to say I genuinely love the field so far.

However, the only benefit I've got from my local university is that it saves me from military while I study. Past year 2 (out of 4, country-specific quirks) there was roughly one subject actually worth paying attention to, so I also have switched to a "just get a decent grade at any cost" mode, as most of the material we're studying (and especially most of the assignments we've done) has negative value in real world.

Most of my peers consider me both more enthused and more knowledgeable than the average student, which mostly makes me realise that roughly 95% of my peers don't care about the contents of the courses.

All this is to say that, while grading is hard, the only thing that might get people to actually care is a proper course, no matter what threats you make.

Re: My university uses prompt injection to catch cheaters

#14

Post by lukewarm707 » Mon, Apr 06, 2026, 9:42 AM UTC

i wonder why the labs don't put a small model for detecting prompt injection in front of the main llm.

it's 20b at most and it can work quite well.

for now you can proxy http through llama guard. 'luxury' security if you can build and pay.

is there an architectural limitation?

Re: My university uses prompt injection to catch cheaters

#15

Post by lukewarm707 » Mon, Apr 06, 2026, 9:44 AM UTC

zeroCalories wrote: post #8

petterroea wrote: post #6

Earlier quoted context omitted.

The student is attending college to get a job. Most students don't care about the course. Probably around 50% of students in my year were only in it for the well paying jobs a prestigious degree like that could give them. This has to be part of the threat model for cheating.

It's pointless. Just an arms race of gimmicks. There's really no option besides making homework all optional, and putting 100% of the grade into in-person exams. I basically don't trust that any new graduate has earned their degree, and won't until schools do what's necessary to crush cheaters.

the course is now no longer cs/swe.

the course is now

"how to pass exams in cs/swe"

Re: My university uses prompt injection to catch cheaters

#16

Post by adityamwagh » Mon, Apr 06, 2026, 1:25 PM UTC

volemo wrote: post #11

petterroea wrote: post #10

Earlier quoted context omitted.

I agree with you in spirit, but the last meta pre-LLM was that exams were bad at measuring student skill and that students felt more fairly treated when their grade was the result of multiple assignments and projects. I think it's a shame we have move away from that

> exams were bad at measuring student skill They are. I have a friend who was significantly more smart and thorough in our studies but often get bad scores on exams not being able to concentrate under the pressure.

Isn’t that actually a valid way to test? IMHO Performing under pressure is a capability signal in itself.

Re: My university uses prompt injection to catch cheaters

#17

Post by zeroCalories » Mon, Apr 06, 2026, 1:28 PM UTC

lukewarm707 wrote: post #15

zeroCalories wrote: post #8

Earlier quoted context omitted.

It's pointless. Just an arms race of gimmicks. There's really no option besides making homework all optional, and putting 100% of the grade into in-person exams. I basically don't trust that any new graduate has earned their degree, and won't until schools do what's necessary to crush cheaters.

the course is now no longer cs/swe. the course is now "how to pass exams in cs/swe"

Better than "how to get a passing grade in cs/swe"

Re: My university uses prompt injection to catch cheaters

#18

Post by dpoloncsak » Mon, Apr 06, 2026, 1:35 PM UTC

subscribed wrote: post #5

Good. I wouldn't like cheaters to compete with honest students on the job market. In my kid's school (American high school equivalent) being caught on using LLM in papers is a failed subject. Students must pass all the subjects to finish the school. Some of these subjects won't be taught the next year so effectively they lose year, two, three....

[flagged]

Re: My university uses prompt injection to catch cheaters

#19

Post by wildzzz » Mon, Apr 06, 2026, 1:51 PM UTC

dpoloncsak wrote: post #18

subscribed wrote: post #5

Good. I wouldn't like cheaters to compete with honest students on the job market. In my kid's school (American high school equivalent) being caught on using LLM in papers is a failed subject. Students must pass all the subjects to finish the school. Some of these subjects won't be taught the next year so effectively they lose year, two, three....

[flagged]

It really depends on the field you go into. If you're a writer and you want a job writing things, you go to college to become a better writer and prepare yourself for working in that industry. If the professors just let you turn in AI slop, how does that benefit anyone? You didn't write anything, why are you here paying tuition? And it demonstrates to the industry that if colleges are handing out degrees to writers for AI slop, why do they even need writers? Just cut the middleman out and they can make the slop themselves.

You go to school to learn. Turning in AI slop doesn't teach you anything. You didn't have to research the subject and commit time to crafting the work into something good. You just typed in a prompt (or copy and pasted it) and then turned in whatever the computer made. The point of learning isn't to turn in assignments, it's to learn and demonstrate your knowledge via assignments. If you want to get a job producing AI slop, don't bother going to school.

Re: My university uses prompt injection to catch cheaters

#20

Post by volemo » Mon, Apr 06, 2026, 1:56 PM UTC

adityamwagh wrote: post #16

volemo wrote: post #11

Earlier quoted context omitted.

> exams were bad at measuring student skill They are. I have a friend who was significantly more smart and thorough in our studies but often get bad scores on exams not being able to concentrate under the pressure.

Isn’t that actually a valid way to test? IMHO Performing under pressure is a capability signal in itself.

Well, that is a way to test students’ ability to perform under pressure, but I’m adamant it’s not a fair assessment of their skill in the subject at hand, nor how much they’d worked and improved during the course. On several occasions I have gotten higher marks than my friend because of their anxiety issues, despite me being a worse student and arguably a worse researcher (what we studied for).