libwebp CVE-2021-40775 RCE Exploit Code and Remediation

根据提供的截图，这是一个关于 CVE-2021-40775 漏洞的 GitHub 仓库页面（具体是 仓库）。 1. 漏洞概述 (Vulnerability Overview): CVE ID: CVE-2021-40775 漏洞类型: 远程代码执行 (Remote Code Execution, RCE)。 受影响组件: 这是一个针对 库的漏洞。 描述: 截图中的 README 文件提到，这是一个在 中存在的漏洞，允许攻击者通过构造恶意 WebP 图像文件来触发远程代码执行。 2. 影响范围 (Affected Scope): 库: (Google 开发的 WebP 图像编解码库)。 版本: 截图中的代码和描述暗示这影响了特定版本的 。虽然具体的版本号在截图中没有直接以列表形式列出，但通常这类 CVE 会指明受影响的版本范围（例如 或类似）。从代码中的 和 相关函数调用来看，它针对的是解码过程。 相关软件: 任何使用受感染版本 的软件都可能受到影响，包括但不限于浏览器（Chrome, Firefox 等）、图像处理软件（GIMP, ImageMagick 等）以及操作系统组件。 3. 修复方案 (Remediation): 官方修复: 截图中的 README 提到 "Fixed in libwebp 1.2.0"（在 libwebp 1.2.0 中已修复）。 建议: 升级 库到 1.2.0 或更高版本。 4. 代码提取 (Code Extraction): 截图包含了一个名为 的文件内容，这是一个 C 语言编写的利用代码（POC/Exploit）。 文件: 内容: 这是一个完整的 C 程序，用于生成一个恶意的 WebP 文件。 它包含 函数。 它定义了 函数，接受命令行参数。 它包含大量的硬编码数据（看起来是构造的 WebP 文件头和数据块）。 它包含 系统调用来将构造的数据写入文件。 它包含 调用来执行命令（这是 RCE 的关键部分）。 代码中有一个 变量，用于存储要执行的命令。 代码中有一个 变量，用于存储 shellcode 或 payload。 代码逻辑是构造一个特定的 WebP 文件结构，利用 的解码漏洞来执行 中指定的命令。 总结: 这是一个关于 远程代码执行漏洞 (CVE-2021-40775) 的 GitHub 仓库。它提供了一个 C 语言编写的利用代码 ( )，用于生成恶意 WebP 文件。该漏洞已在 1.2.0 版本中修复。 提取代码: 注意：由于截图中的代码非常长且包含大量十六进制数据，我将提取关键部分和结构。 最终输出结构: 1. 漏洞概述: CVE-2021-40775, libwebp RCE. 2. 影响范围: libwebp < 1.2.0. 3. 修复方案: 升级到 libwebp 1.2.0+. 4. POC/Exploit 代码: 提取 的内容。 Let's refine the code extraction based on the visual content. The code is quite long. I will try to capture the essence and the structure as seen in the image. The image shows a C file . The code starts with includes: Then function. It takes arguments. It defines a variable. It defines a variable (shellcode). It constructs a WebP file. It writes the file. It executes the command using . Wait, looking closer at the bottom part of the code in the image: It seems to be generating a file . It uses to write data. The data includes a lot of hex bytes. Finally, it calls . Actually, looking at the very bottom, it seems the code is just generating the file. The execution happens when the file is processed by a vulnerable decoder. But the code itself might also have a call if it's a local exploit or if it's demonstrating the payload injection. Let's look at the function logic again. It seems to be a generator. ... ... ... Wait, there is a call in the middle? Let's look at line 130-140 area. is visible. So the exploit code itself executes the command? Or is it part of the payload generation? Ah, looking at the code structure: It seems to be a C program that generates the malicious WebP file. But why would it call ? Maybe it's a local exploit that triggers the vulnerability in a specific way, or maybe the is just used to name the file or something? No, suggests the user provides the command. And is called. This suggests the C program itself is the exploit, and it might be using the vulnerability to execute the command, or it's just a simple wrapper. Actually, looking at the code again, it seems to be constructing a WebP file that contains the shellcode, and then maybe it's trying to trigger it? Or maybe the is just a test to show that the command would be executed if the vulnerability was triggered? No, is a standard C library call. It executes the command immediately. So this C program is likely a generator that creates a malicious WebP file, and the part might be a mistake in my reading or it's a specific type of exploit. Let's re-examine the code block in the image. The code is . It includes , , , . function. (shellcode) ... ... ... ... Wait, I see in the code? Let's look at the bottom part again. Line 130: Line 131: So the program does execute the command. This is strange for a file generator. Unless... the is not the command to execute, but part of the payload? No, and is clear. Maybe the exploit works by creating a file and then immediately executing a command? That doesn't make sense for a remote code execution via image parsing. Unless the "exploit" is actually a local script that creates the file and then does something else? Or maybe the is part of the payload injection logic? No, is a C function. Let's look at the README text again. "Remote Code Execution in libwebp" "Fixed in libwebp 1.2.0" "Exploit code is provided in exploit.c" Okay, let's assume the code is a generator. Why would a generator call ? Maybe the is the command to be embedded in the WebP file? But executes it now. Maybe the code is: 1. Generate the malicious WebP file. 2. Execute the command (maybe to verify something or as a side effect?). Or maybe the is just a string that gets written into the file, and the is a red herring or I'm misinterpreting the code flow. Let's look at the code lines around . Line 128: Line 129: Line 130: This is very weird. If I run , it will create and then run . This suggests the C program is not just a generator, but also an executor. But how does it relate to the vulnerability? Maybe the vulnerability allows arbitrary code execution when parsing the file, and this C program is demonstrating that by creating a file that, when parsed, executes the command? But the C program itself calls . This implies the C program is the e

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libwebp CVE-2021-40775 RCE Exploit Code and Remediation

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libwebp CVE-2021-40775 RCE Exploit Code and Remediation

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