The Saving Prescription
The Saving Prescription
Platform: hackerlab | Category: Steganography | Type: Challenge | Difficulty: Medium | OS: NA | Author: XESXOR | Date: 2026-04-05 | Status: Solved Techniques: ascii_code_decoding, document_analysis, historical_context_verification, numeric_to_ascii_conversion
Summary
Task: a PNG image of a Russian medical prescription from 1962 with 23 medications and dosages in mg. Solution: recognize that all dosage values fall in the printable ASCII range, convert each number to its ASCII character to reveal a hidden leetspeak message — the flag.
The Saving Prescription — Hackerlab
Description
В 1962 году произошёл громкий побег трёх заключённых из тюрьмы Алькатрас. Недавно энтузиаст с нашей платформы обнаружил в интернет-архивах отсканированный медицинский рецепт, который мог быть выписан тюремным врачом одному из заключённых. Проверьте подлинность этого документа. Может ли это быть ещё одной уликой или просто шуткой энтузиаста?
English summary: In 1962, three inmates famously escaped from Alcatraz prison. An enthusiast found a scanned medical prescription in internet archives, allegedly issued by the prison doctor to one of the inmates. We must verify the document's authenticity and determine whether it's a real clue or a prank. A ZIP file is provided containing a PNG image of the prescription.
Analysis
File reconnaissance
The provided lifesaving_recipe.zip contained a single file: Спасительный рецепт.png — a PNG image of a Russian-language medical prescription form.
Document contents
The prescription form contains the following details:
| Field | Value | Historical significance |
|---|---|---|
| Date | June 10, 1962 | One day before the real Alcatraz escape (June 11, 1962) |
| Patient | Фрэнк Моррис (Frank Morris) | One of the three actual Alcatraz escapees |
| Date of birth | September 1, 1927 | Matches Frank Morris's real birth date |
| Doctor | Джордж Хесс (George Hess) | Prison doctor name |
| |
The prescription lists 23 medications with dosages in milligrams:
| # | Medication | Dosage (mg) | ASCII |
|---|---|---|---|
| 1 | Амиксин | 51 | 3 |
| 2 | Арбидол | 115 | s |
| 3 | Парацетамол | 99 | c |
| 4 | Гриппферон | 52 | 4 |
| 5 | Ингавирин | 112 | p |
| 6 | АЦЦ | 101 | e |
| 7 | Цефтриаксон | 95 | _ |
| 8 | Флуифорт | 116 | t |
| 9 | Бромгексин | 111 | o |
| 10 | Ринколд | 109 | m |
| 11 | Лазолван | 48 | 0 |
| 12 | Витамин С | 114 | r |
| 13 | Амбробене | 114 | r |
| 14 | Терафлю | 48 | 0 |
| 15 | Аспирин | 119 | w |
| 16 | Ремантадин | 95 | _ |
| 17 | Фарингосент | 101 | e |
| 18 | Эргоферон | 118 | v |
| 19 | Називин | 51 | 3 |
| 20 | Эвкабал | 110 | n |
| 21 | Кагоцел | 49 | 1 |
| 22 | Иммунал | 110 | n |
| 23 | Синупрет | 103 | g |
| |
Key observation
All 23 dosage values fall within the printable ASCII range (48–119). This is the critical indicator — real medication dosages would vary widely (e.g., 250mg, 500mg, 1000mg), but these are all suspiciously small and clustered in the 48–119 range.
Solution
Step 1: Extract the dosage values
Read the prescription image and extract all 23 dosage numbers in order.
Step 2: Convert to ASCII characters
python read-only • copy allowed#!/usr/bin/env python3 # Solve script: convert medication dosages to ASCII characters dosages = [ 51, 115, 99, 52, 112, 101, 95, 116, 111, 109, 48, 114, 114, 48, 119, 95, 101, 118, 51, 110, 49, 110, 103 ] message = ''.join(chr(d) for d in dosages) print(f"Decoded message: {message}") print(f"Flag: CODEBY{{{message}}}")
Output:
Decoded message: REDACTED
Flag: CODEBY{REDACTED}
Step 3: Interpret the message
The decoded string REDACTED is leetspeak for "escape tomorrow evening" — a coded escape instruction hidden in a fake medical prescription. Since the prescription is dated June 10, 1962, "tomorrow evening" refers to June 11, 1962 — the exact date of the real Alcatraz escape by Frank Morris and the Anglin brothers.