TrickBot is a notorious malware usually distributed via spam mails; after infecting the system it downloads various files and modules to run and seize domain’s Active Directory Services database, harvest browser passwords, and cookies, steal OpenSSH keys. It is also known to often give access to ransomware operators like Ryuk and Conti on the infected network.
This mistake by TrickBot occurred during the testing of their password-stealing “grabber.dll”, this particular strain steals passwords, browser credentials, cookies from browsers like Google, Internet Explorer and Microsoft Edge. During the testing of this grabber.dll module, this particular warning message was issued on the attacked system revealing that some information has been gathered from the browser defeating the purpose.
“You see this message because the program named grabber gathered some information from your browser. If you do not know what is happening it is the time to start worrying. Please, ask your system administrator for details.”
Source: E Hacking news
TrickBot accidentally issues infection warning to Victims