FoF Pretty Mail 1.1.2 Server-Side Template Injection

Exploit Title: FoF Pretty Mail 1.1.2 Extension for Flarum Server-SideTemplate Injection (SSTI)Date: 03/28/2024Exploit Author: Chokri HammediVendor Homepage: https://flarum.org/Software Link: https://github.com/FriendsOfFlarum/pretty-mailVersion: 1.1.2Tested on: Windows XPCVE: N/ADescription:The FoF Pretty Mail extension for Flarum is vulnerable to Server-SideTemplate Injection (SSTI) due to the unsafe handling of template variables.An attacker with administrative access can inject malicious code into theemail template, leading to arbitrary code execution on the server.Steps to Reproduce:Log in as an administrator on the Flarum forum.Navigate to the FoF Pretty Mail extension settings.Edit the email default template and insert the following payload:{{ 7*7 }}{{ system('id') }}{{ system('echo "Take The Rose"') }}Save the changes to the email template.Trigger any action that sends an email, such as user registration orpassword reset.The recipient of the email will see the result of the injected expressions(e.g., "49" for {{ 7*7 }}, the output of the id command for {{ system('id')}}, and the output of the echo "Take The Rose" command for {{ system('echo"Take The Rose"') }}) in the email content.