https://clairis.cn/tags/buuctf/ Recent content in BUUCTF on Clairis's Blog Hugo zh-cn Sat, 18 Jul 2026 00:00:00 +0000 https://clairis.cn/posts/17buuctf/ Fri, 17 Jul 2026 00:00:00 +0000 https://clairis.cn/posts/17buuctf/ <h1 id="misc">Misc</h1> <h2 id="01金三胖">01金三胖</h2> <p><a href="https://ctf2.dasctf.com/dashboard/practice/b9bbb32f-f186-458f-b90b-12440c0f6aea?tab=challenges&amp;challenge=1b398a3e-2f59-4034-bf03-8c404e28d793">CTF²</a> 下载附件得到一份GIF文件，打开GIF文件看到中间会闪过疑似flag，于是分离GIF</p> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-Bash" data-lang="Bash"><span class="line"><span class="cl">sudo apt install imagemagick </span></span><span class="line"><span class="cl">convert aaa.gif frame_%03d.png </span></span></code></pre></div><p><img src="17buuctf/img-001.png" alt=""><img src="17buuctf/img-002.png" alt=""><img src="17buuctf/img-003.png" alt=""> 得到flag</p> <hr> <h2 id="02二维码">02二维码</h2> <p><a href="https://ctf2.dasctf.com/dashboard/practice/b9bbb32f-f186-458f-b90b-12440c0f6aea?tab=challenges&amp;challenge=7a44e5a1-beea-4663-9b23-ebe1baf38765">CTF²</a> 先用QRCode扫码得到 <img src="17buuctf/img-004.png" alt=""> 直接扫描并没有得到flag</p> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-Bash" data-lang="Bash"><span class="line"><span class="cl"> strings QR_code.png </span></span></code></pre></div><p><img src="17buuctf/img-005.png" alt=""> 于是binwalk提取得到<code>1D7</code>压缩包，尝试解压但是需要密码 <img src="17buuctf/img-006.png" alt=""> 压缩包中的文件为<code>4number.txt</code>，所以密码很可能是4位纯数字，用fcrackzip爆破</p> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-Bash" data-lang="Bash"><span class="line"><span class="cl">fcrackzip -b -c <span class="m">1</span> -l 4-4 -u 1D7.zip </span></span></code></pre></div><p><img src="17buuctf/img-007.png" alt=""> 接下来继续解压缩得到txt文件，进而得到flag <img src="17buuctf/img-008.png" alt=""></p> <hr> <h2 id="03n种方法解决">03N种方法解决</h2> <p><a href="https://ctf2.dasctf.com/dashboard/practice/b9bbb32f-f186-458f-b90b-12440c0f6aea?tab=challenges&amp;challenge=b797fb16-93d2-48c1-b624-9b0f21505f9d">CTF²</a> 先检查文件类型</p> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-Bash" data-lang="Bash"><span class="line"><span class="cl">file KEY.exe </span></span></code></pre></div><p>得到结果说明它实际上是txt文本文件 接下来查看文件头</p> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-Bash" data-lang="Bash"><span class="line"><span class="cl">head -c <span class="m">100</span> KEY.exe </span></span></code></pre></div><p><img src="17buuctf/img-009.png" alt=""></p> <blockquote> <p>文件类型：jpg图片 + Base64编码的图片数据</p> </blockquote> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-Bash" data-lang="Bash"><span class="line"><span class="cl">sed <span class="s1">&#39;s/^data:image\/[^;]*;base64,//&#39;</span> KEY.exe <span class="p">|</span> base64 -d &gt; key.png </span></span></code></pre></div><p>解码得出一张二维码 但原二维码比较小且缺乏足够的白色边缘，需要放大并添加白边</p> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-Bash" data-lang="Bash"><span class="line"><span class="cl">agick key.png -filter point -resize 800% <span class="se">\ </span></span></span></code></pre></div><p>再用扫码工具扫码 <img src="17buuctf/img-010.png" alt=""></p> <hr> <h2 id="04大白">04大白</h2> <p><a href="https://ctf2.dasctf.com/dashboard/practice/b9bbb32f-f186-458f-b90b-12440c0f6aea?tab=challenges&amp;challenge=c99d060f-ba8b-4803-a23e-52b4b8a34b68">CTF²</a> 打开图片发现只有上半截，于是修改宽高 <img src="17buuctf/img-011.png" alt=""></p> <hr> <h2 id="05你竟然赶我走">05你竟然赶我走</h2> <p><a href="https://ctf2.dasctf.com/dashboard/practice/b9bbb32f-f186-458f-b90b-12440c0f6aea?tab=challenges&amp;challenge=84589c09-0bc0-4076-89cd-fa742175eece">CTF²</a> 从文件中提取能直接显示的可读字符串</p> <div class="highlight"><pre tabindex="0" class="chroma"><code class="language-Bash" data-lang="Bash"><span class="line"><span class="cl">strings biubiu.jpg </span></span></code></pre></div><p>在输出中直接看到flag</p>