---
title: "Comment by Kartik N V J K on \"I attacked my own finance bot. The fix wasn't a better prompt.\" | Hashnode"
description: "A zero-size \"paid in full\" line closing a bill and silently killing the reminders is nastier than most injection demos I've seen, because nothing looks wrong to"
url: "https://hashnode.com/posts/i-attacked-my-own-finance-bot-the-fix-wasn-t-a-better-prompt/6acc5d11b64aa9414a3a36e1/comment/6ace61a00b5bdc034a0e1b6d"
---

[Discussion](https://hashnode.com/posts/i-attacked-my-own-finance-bot-the-fix-wasn-t-a-better-prompt/6acc5d11b64aa9414a3a36e1)

Comment [I attacked my own finance bot. The fix wasn't a better prompt.](https://hashnode.com/posts/i-attacked-my-own-finance-bot-the-fix-wasn-t-a-better-prompt/6acc5d11b64aa9414a3a36e1)

[Kartik N V J K](https://hashnode.com/@kartik-nvj)

[Oct 13](https://hashnode.com/posts/i-attacked-my-own-finance-bot-the-fix-wasn-t-a-better-prompt/6acc5d11b64aa9414a3a36e1/comment/6ace61a00b5bdc034a0e1b6d)

A zero-size "paid in full" line closing a bill and silently killing the reminders is nastier than most injection demos I've seen, because nothing looks wrong to anyone. I like that you swapped the model for a fake that can return any well-formed answer and tested the app's behavior instead. Did the hidden-text check need much tuning to hit zero false flags across those 60 real bills?

[Mahesh](https://hashnode.com/@filtercoffeeway)

[Oct 18](https://hashnode.com/posts/i-attacked-my-own-finance-bot-the-fix-wasn-t-a-better-prompt/6acc5d11b64aa9414a3a36e1/comment/6ace61a00b5bdc034a0e1b6d#reply-6ad466eed76958580581094b)

Thank you. No, I did not tune it. But the "zero" needs a note. The hidden-text check alone flagged 12 of 60 runs (20%). Four bills have a hidden preview line, and the check flags them. A second read of the bill follows each flag. If the two reads agree, the bill goes through. This gives 0 false flags in 60. I tried a higher threshold. False flags fell, but detection fell from 8 of 8 to 1 of 8. So I kept the strict setting. The 60 runs are 20 test bills, each run 3 times. They are not real mail. The real rate is not known yet. A metric in production will show it.