https://picoctf-writeup.pinjim.dev/tags/picoctf-2023/Recent content in PicoCTF 2023 on picoCTF WriteupHugoen-usWed, 01 Jul 2026 22:30:00 +0800https://picoctf-writeup.pinjim.dev/posts/general-skills/repetitions/Wed, 01 Jul 2026 22:30:00 +0800https://picoctf-writeup.pinjim.dev/posts/general-skills/repetitions/<h2 id="題目連結">題目連結</h2> <p><a href="https://learn.cylabacademy.org/library/371">https://learn.cylabacademy.org/library/371</a></p> <h2 id="題目解法">題目解法</h2> <p>下載後得到以下字串</p> <pre tabindex="0"><code>VmpGU1EyRXlUWGxTYmxKVVYwZFNWbGxyV21GV1JteDBUbFpPYWxKdFVsaFpWVlUxWVZaS1ZWWnVh RmRXZWtab1dWWmtSMk5yTlZWWApiVVpUVm10d1VWZFdVa2RpYlZaWFZtNVdVZ3BpU0VKeldWUkNk MlZXVlhoWGJYQk9VbFJXU0ZkcVRuTldaM0JZVWpGS2VWWkdaSGRXCk1sWnpWV3hhVm1KRk5XOVVW VkpEVGxaYVdFMVhSbFZrTTBKVVZXcE9VazFXV2toT1dHUllDbUY2UWpSWk1GWlhWa2RHZEdWRlZs aGkKYlRrelZERldUMkpzUWxWTlJYTkxDZz09Cg== </code></pre><p>看到用兩個等於結尾且內容皆為字母及數字，推測使用 base64 編碼，解碼後得到以下字串</p> <pre tabindex="0"><code>VjFSQ2EyTXlSblJUV0dSVllrWmFWRmx0TlZOalJtUlhZVVU1YVZKVVZuaFdWekZoWVZkR2NrNVVX bUZTVmtwUVdWUkdibVZXVm5WUgpiSEJzWVRCd2VWVXhXbXBOUlRWSFdqTnNWZ3BYUjFKeVZGZHdW MlZzVWxaVmJFNW9UVVJDTlZaWE1XRlVkM0JUVWpOUk1WWkhOWGRYCmF6QjRZMFZXVkdGdGVFVlhi bTkzVDFWT2JsQlVNRXNLCg== </code></pre><p>在解碼一次得到</p> <pre tabindex="0"><code>V1RCa2MyRnRTWGRVYkZaVFltNVNjRmRXYUU5aVJUVnhWVzFhYVdGck5UWmFSVkpQWVRGbmVWVnVR bHBsYTBweVUxWmpNRTVHWjNsVgpXR1JyVFdwV2VsUlZVbE5oTURCNVZXMWFUd3BTUjNRMVZHNXdX azB4Y0VWVGFteEVXbm93T1VOblBUMEsK </code></pre><p>在解碼一次得到</p> <pre tabindex="0"><code>WTBkc2FtSXdUbFZTYm5ScFdWaE9iRTVxVW1aaWFrNTZaRVJPYTFneVVuQlpla0pyU1ZjME5GZ3lV WGRrTWpWelRVUlNhMDB5VW1aTwpSR3Q1VG5wWk0xcEVTamxEWnowOUNnPT0K </code></pre><p>在解碼一次得到</p> <pre tabindex="0"><code>Y0dsamIwTlVSbnRpWVhObE5qUmZiak56ZEROa1gyUnBZekJrSVc0NFgyUXdkMjVzTURSa00yUmZO RGt5TnpZM1pESjlDZz09Cg== </code></pre><p>在解碼一次得到</p> <pre tabindex="0"><code>cGljb0NURntiYXNlNjRfbjNzdDNkX2RpYzBkIW44X2Qwd25sMDRkM2RfNDkyNzY3ZDJ9Cg== </code></pre><p>在解碼一次得到 flag</p> <pre tabindex="0"><code>picoCTF{bas------------------------------------7d2} </code></pre>