← All Challenges

Challenge 03: Character Code Construction

Difficulty: Easy
Category: Signature Detection Bypass

---

Objective

Bypass the scanner’s signature detection by representing your payload string as numeric values rather than text. The scanner must see only numbers in your file, not the target string.

Scanner Behavior

The scanner performs static byte-pattern matching against file contents. It searches for the following strings as contiguous byte sequences:

• malware
• virus
• trojan
• evil_payload
• dropper
• ransomware
• payload.exe

The scanner performs a literal byte search. It does not interpret numeric literals, arrays, or data structures. If the ASCII text of the signature doesn’t appear in the file, the scanner won’t flag it.

Rules

• Your script must reconstruct one of the blocked strings at runtime from numeric character codes.
• The file must not contain any of the blocked strings as readable text.
• The approach must use the numeric representation of characters (ASCII/Unicode code points).

Hints

1. Every character has a corresponding number. The letter m is 109, a is 97, and so on.
2. What if the scanner only sees an array of integers?
3. Languages have functions to convert numbers back into characters at runtime.
4. An array like @(109, 97, 108) looks nothing like the word it represents.

---

View Solution