好的，我现在需要帮用户总结一篇文章的内容，控制在100字以内，并且不需要特定的开头。首先，我得仔细阅读用户提供的文章内容，理解其主要信息。 这篇文章看起来是关于NSA的Code Breaker Challenge 2025的。开头介绍了这是一个年度活动，类似于CTF比赛，涉及各种安全挑战。今年的挑战提供了一个ext2磁盘映像，用户需要从中寻找可疑的东西。 接下来，文章详细描述了如何下载和挂载磁盘映像，并检查目录结构。发现了非默认的Linux目录，如/app和/backup。然后使用ls -la命令遍历根目录下的子目录，发现文件系统不大，主要包含常规系统文件。 文中提到这是Alpine Linux系统，使用Busybox来捆绑核心Linux二进制文件，说明这个映像可能来自嵌入式设备或IoT设备。接着检查/etc目录下的periodic文件，发现了一个可疑的任务文件。 总结下来，文章主要讲述了CBC 2025的第一部分任务：分析Alpine Linux磁盘映像，寻找恶意文件。因此，在总结时需要涵盖这些关键点：挑战内容、磁盘映像分析、系统类型、发现的任务文件。 现在我需要用简洁的语言把这些信息浓缩到100字以内，并且直接描述内容。避免使用“这篇文章”或“文章内容总结”这样的开头。 可能的结构是：介绍挑战、分析磁盘映像、发现异常目录和任务文件。确保涵盖所有重要信息：CTF比赛、磁盘映像、Alpine Linux、Busybox、任务文件。 最后检查字数是否在限制内，并确保语句通顺自然。 </think> NSA的Code Breaker Challenge 2025是一个CTF比赛风格的年度活动，参与者需分析一个ext2磁盘映像以寻找可疑内容。该映像基于Alpine Linux系统，使用Busybox捆绑核心二进制文件，可能来自嵌入式设备或IoT设备。通过检查目录结构和文件内容，最终在/etc/periodic中发现了一个可疑的任务文件。 2026-1-25 14:13:46 Author: infosecwriteups.com(查看原文) 阅读量:1 收藏
Hello everyone and welcome to NSA’s Code Breaker Challenge for 2025! NSA CBC is a yearly event put on by the NSA that is for all intents and purposes a CTF. Challenge topics vary from forensics to reverse engineering and they’re always pretty fun and challenging. Starting off this year it looks like we’re given a disk image that we’ve gotta comb through for something suspicious. So, without further adieu, let’s dive into Code Breaker Challenge 2025.
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So to start off here, we’re given a little scenario to get us in the mindset for these challenges as well as a zip file that is has a ext2 disk image inside. Well, seems fairly straight forward so far, let’s go ahead download and mount this image and start looking through it.
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Right off the bat we can see that in this directory structure there are a few directories that aren’t default Linux directories. The culprits being /app and /backup, let’s see what’s there.
Nothing huh? Alright, well let’s just start combing through some of these directories and seeing what we can find.
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Here you see me running ls -la on pretty much every subdirectory in root here and honestly this file system is not very big. We only have files in /bin /dev /etc /lib /media /root /run /usr and /var. That may sound like a lot, but it could be a lot worse and also a lot of this stuff looks pretty regular. Also a couple other interesting notes.
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We have this alpine-release file here, which tells us the is an Alpine Linux box. Another little interesting tidbit.
All of our normal binaries are now linked to busybox. Why are these two things significant? Alpine Linux utilizes Busybox (which is basically a bundle core Linux binaries bundled together) because it is frequently used as the OS for embedded systems. Alpine is super lightweight, and efficient which makes it ideal for use in systems that need to be extremely efficient and don’t have a ton of resources. So this image could be of some kind of IoT device or home router or something. Does that mean anything for us here? Maybe, maybe not we’ll have to keep looking and see.
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Anything interesting here in /etc? This would be a good place to drop a malicious file, maybe they placed something in cron for persistence?
Hmmm, /etc/periodic? What’s that?
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So Periodic is like a FreeBSD implementation of cron huh? Well let’s see what’s in /etc/periodic.
What the heck is that?
Now this looks kinda janky, let’s see if this is the suspicious file.
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Bam and that’s Task 1 of CBC 2025!
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