asepharyana
7a6e717c28
- Deleted all previous dummy docs (defcon-quals-2024, infra/cloudflare-525, debugging/websocket-timeout, template, docs/*, notes/*, research/*) - Added 14 Gemastik warmup writeups covering encoding, stego, web, pwn, crypto - ch13: RSA small factors; ch14: RSA special integers via paper-search (GCD with paper appendix primes) - All flags recovered and documented with solution methods
49 lines
2.2 KiB
Markdown
49 lines
2.2 KiB
Markdown
---
|
|
title: "GEMASTIK 2026 Warmup — All Chapters"
|
|
event: "GEMASTIK 2026 Warmup"
|
|
category: "index"
|
|
points: 0
|
|
difficulty: "index"
|
|
---
|
|
|
|
# GEMASTIK 2026 Warmup — Chapter Index (ch1–ch14)
|
|
|
|
**Platform:** [Warmup GEMASTIK 2026](https://warmup-cybersecurity.apps.binus.ac.id) (CTFd)
|
|
**Status:** 14/14 solved — 7001 points (13×500 + 1×501)
|
|
|
|
| # | Challenge | Category | Diff | Flag |
|
|
|---|-----------|----------|------|------|
|
|
| 1 | Sixty Four | Encoding | easy | `GEMASTIK19{b4s3_s1xty_f0ur_warm1ng_up}` |
|
|
| 2 | Julius | Caesar/ROT13 | easy | `GEMASTIK19{caesar_r0t_th1rt33n_klasik}` |
|
|
| 3 | Needle | Forensics/strings | easy | `GEMASTIK19{str1ngs_c4n_f1nd_m3}` |
|
|
| 4 | Say Cheese | EXIF metadata | easy | `GEMASTIK19{h1dd3n_1n_m3tadata_exif}` |
|
|
| 5 | Nothing Here | Web comment | easy | `GEMASTIK19{v13w_s0urc3_pahlawan}` |
|
|
| 6 | Sweet Cookie | Web/cookie | easy | `GEMASTIK19{c00k13_b4s3_d3c0d3}` |
|
|
| 7 | Open Book | Source | easy | `GEMASTIK19{pyth0n_s0urc3_t3rbuka}` |
|
|
| 8 | Back and Forth | XOR | easy | `GEMASTIK19{x0r_it_back_4gain}` |
|
|
| 9 | Are You Admin? | Pwn/bof | easy | `GEMASTIK19{0v3rfl0w_ubah_var}` |
|
|
| 10 | Call Me | Pwn/ret2win | easy | `GEMASTIK19{r3t2w1n_l0mpat_k3_win}` |
|
|
| 11 | Behind the Picture | PNG stego | easy | `GEMASTIK19{c4t_g4mbar_ada_flag}` |
|
|
| 12 | Layers | Hex→B64 chain | easy | `GEMASTIK19{h3x_lQlu_b4s3_ch41n}` |
|
|
| 13 | Slopped | RSA small factors | medium | `GEMASTIK19{qu4ntum_c0mput3r_br0k3_rs4_y0u_sh0uld_us3_p4p3r_s34rch_mcp_sk1ll}` |
|
|
| 14 | Slopped wave-2 | RSA paper search | hard | `GEMASTIK19{test_vector_of_listP_on_quant}` |
|
|
|
|
## Ringkasan Metode
|
|
|
|
| Ch | Metode | Tool |
|
|
|----|--------|------|
|
|
| 1 | Double Base64 | `base64 -d` ×2 |
|
|
| 2 | ROT13 Caesar | `codecs.encode(s, "rot_13")` |
|
|
| 3 | strings | `strings secret.bin` |
|
|
| 4 | EXIF metadata | `strings photo.jpg` |
|
|
| 5 | HTML comment | `curl \| grep '<!--'` |
|
|
| 6 | Base64 cookie | `base64 -d` |
|
|
| 7 | ASCII codes | chr() decoding |
|
|
| 8 | Single-byte XOR | XOR 0x42 |
|
|
| 9 | Stack overflow | buffer > admin |
|
|
| 10 | ret2win + align | ROP chain |
|
|
| 11 | PNG strings | `strings kucing.png` |
|
|
| 12 | Hex→Base64 | `bytes.fromhex` + `b64decode` |
|
|
| 13 | RSA small factors | trial division / sympy factorint |
|
|
| 14 | RSA special integers | GCD with paper appendix primes |
|