asepharyana
0de2458955
- Deleted all 14 dummy docs from DB + filesystem - Created 14 Gemastik warmup writeups + index via create_document API (DB-first) - ch1-ch12: encoding/stego/web/pwn basics - ch13: RSA small factors - ch14: RSA special integers via paper-search (GCD with paper appendix primes) - All 15 docs indexed and live at wiki.asepharyana.my.id
58 lines
2.5 KiB
Markdown
58 lines
2.5 KiB
Markdown
---
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title: "GEMASTIK 2026 Warmup — All Chapters"
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type: "writeup"
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section: "writeups"
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status: "published"
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author: "asep"
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tags: ["gemastik", "ctf", "warmup", "writeup-index"]
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path: "writeups/gemastik-2026-warmup/_index.md"
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created_at: "2026-08-21T07:17:48.670Z"
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updated_at: "2026-08-21T07:17:48.670Z"
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---
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---
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title: "GEMASTIK 2026 Warmup — All Chapters"
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event: "GEMASTIK 2026 Warmup"
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category: "index"
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points: 0
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difficulty: "index"
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---
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# GEMASTIK 2026 Warmup — Chapter Index (ch1–ch14)
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**Platform:** [Warmup GEMASTIK 2026](https://warmup-cybersecurity.apps.binus.ac.id) (CTFd)
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**Status:** 14/14 solved — 7001 points (13×500 + 1×501)
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| # | Challenge | Category | Diff | Flag |
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|---|-----------|----------|------|------|
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| 1 | Sixty Four | Encoding | easy | `GEMASTIK19{b4s3_s1xty_f0ur_warm1ng_up}` |
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| 2 | Julius | Caesar/ROT13 | easy | `GEMASTIK19{caesar_r0t_th1rt33n_klasik}` |
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| 3 | Needle | Forensics/strings | easy | `GEMASTIK19{str1ngs_c4n_f1nd_m3}` |
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| 4 | Say Cheese | EXIF metadata | easy | `GEMASTIK19{h1dd3n_1n_m3tadata_exif}` |
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| 5 | Nothing Here | Web comment | easy | `GEMASTIK19{v13w_s0urc3_pahlawan}` |
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| 6 | Sweet Cookie | Web/cookie | easy | `GEMASTIK19{c00k13_b4s3_d3c0d3}` |
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| 7 | Open Book | Source | easy | `GEMASTIK19{pyth0n_s0urc3_t3rbuka}` |
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| 8 | Back and Forth | XOR | easy | `GEMASTIK19{x0r_it_back_4gain}` |
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| 9 | Are You Admin? | Pwn/bof | easy | `GEMASTIK19{0v3rfl0w_ubah_var}` |
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| 10 | Call Me | Pwn/ret2win | easy | `GEMASTIK19{r3t2w1n_l0mpat_k3_win}` |
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| 11 | Behind the Picture | PNG stego | easy | `GEMASTIK19{c4t_g4mbar_ada_flag}` |
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| 12 | Layers | Hex→B64 chain | easy | `GEMASTIK19{h3x_lQlu_b4s3_ch41n}` |
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| 13 | Slopped | RSA small factors | medium | `GEMASTIK19{qu4ntum_c0mput3r_br0k3_rs4_y0u_sh0uld_us3_p4p3r_s34rch_mcp_sk1ll}` |
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| 14 | Slopped wave-2 | RSA paper search | hard | `GEMASTIK19{test_vector_of_listP_on_quant}` |
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### Ringkasan Metode
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| Ch | Metode | Tool |
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|----|--------|------|
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| 1 | Double Base64 | base64 -d ×2 |
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| 2 | ROT13 Caesar | codecs.encode(s, "rot_13") |
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| 3 | strings | strings secret.bin |
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| 4 | EXIF metadata | strings photo.jpg |
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| 5 | HTML comment | curl \| grep '<!--' |
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| 6 | Base64 cookie | base64 -d |
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| 7 | ASCII codes | chr() decoding |
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| 8 | Single-byte XOR | XOR 0x42 |
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| 9 | Stack overflow | buffer > admin |
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| 10 | ret2win + align | ROP chain |
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| 11 | PNG strings | strings kucing.png |
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| 12 | Hex→Base64 | bytes.fromhex + b64decode |
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| 13 | RSA small factors | trial division / sympy factorint |
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| 14 | RSA special integers | GCD with paper appendix primes | |