Cocotais Bot has builtin .echo command injection

Summary

 A command echoing feature in the framework allows users to indirectly trigger privileged behavior by injecting special platform tags. Specifically, an unauthorized user can use the /echo <qqbot-at-everyone /> command to cause the bot to send a message that mentions all members in the chat, bypassing any permission controls. This can lead to spam, disruption, or abuse of notification systems. 

Details

 The framework provides a command /echo that causes the bot to repeat any user-provided message verbatim in the group chat. However, the bot fails to sanitize or filter platform-specific control elements such as <qqbot-at-everyone />, which, when included in a message, mentions everyone (i.e., @全体成员). While normal users are forbidden from using this tag in normal chats, the bot, which has higher privileges, is allowed to do so.  Since the /echo command blindly echoes any content, a user can exploit this by sending: 

/echo <qqbot-at-everyone />

 The bot will then send a message containing <qqbot-at-everyone />, causing the platform to interpret it as an @全体成员 command, effectively allowing an unauthorized user to @everyone via the bot. 

PoC



1. Set up a chatbot using the affected framework.
2. Join the chat that includes the bot as a regular user with no permission to use @全体成员.
3. Send the following message in the chat: 

/echo <qqbot-at-everyone />

4. The bot will respond by repeating the message, and the platform will interpret <qqbot-at-everyone /> as an @全体成员 mention.
5. All the chat members receive a notification, despite the user lacking that permission.