CVE-2021-21425 PoC — Unauthenticated Arbitrary YAML Write/Update leads to Code Execution

Source

https://github.com/frknktlca/GravCMS_Nmap_Script

Associated Vulnerability

Title:Unauthenticated Arbitrary YAML Write/Update leads to Code Execution (CVE-2021-21425)
Description:Grav Admin Plugin is an HTML user interface that provides a way to configure Grav and create and modify pages. In versions 1.10.7 and earlier, an unauthenticated user can execute some methods of administrator controller without needing any credentials. Particular method execution will result in arbitrary YAML file creation or content change of existing YAML files on the system. Successfully exploitation of that vulnerability results in configuration changes, such as general site information change, custom scheduler job definition, etc. Due to the nature of the vulnerability, an adversary can change some part of the webpage, or hijack an administrator account, or execute operating system command under the context of the web-server user. This vulnerability is fixed in version 1.10.8. Blocking access to the `/admin` path from untrusted sources can be applied as a workaround.

Description

It is a nmap script for GravCMS vulnerability (CVE-2021-21425)

Readme

# GravCMS_Nmap_Script
It is a nmap script for GravCMS vulnerability (CVE-2021-21425)

USAGE

-- nmap -p443 --script grav_cms.nse <target>

-- PORT    STATE SERVICE

-- 443/tcp open  https

-- | grav_cms: 

-- |   VULNERABLE:

-- |   GravCMS (CVE-2021-21425)

-- |     State: VULNERABLE (Exploitable)

-- |     IDs:  CVE:CVE-2021-21425

-- |       GravCMS Unauthenticated Arbitrary YAML Write/Update leads to Code Execution

-- |     Disclosure date: 2021-03-19

-- |     References:

-- |       https://pentest.blog/unexpected-journey-7-gravcms-unauthenticated-arbitrary-yaml-write-update-leads-to-code-execution/

-- |_      https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21425

File Snapshot

Remarks

1. It is advised to access via the original source first.

2. Local POC snapshots are reserved for subscribers — if the original source is unavailable, the local mirror is part of the paid plan.

View subscription plans →

Goal Reached Thanks to every supporter — we hit 100%!