German researcher Tobias Mädel descoberto naquela, sob determinadas condições, servidores ProFTPD são vulneráveis à execução remota de código e de informação ataques de divulgação.The root of the problem lies in the mod_copy module bug, que permite que arquivos arbitrários copiando. Mais frequente, este módulo é ativado por padrão.
“Todas as versões de ProFTPd até e incluindo 1.3.6 (o problema estende-se a 1.3.6 only if the compilation date is earlier than 07/17/19) are vulnerable in the mod_copy module“, – reported Tobias Mädel
The bug allows an authenticated user (including an anonymous user) to copy files, even if he does not have permission to write. This behavior is caused by an error in SITE CPFR e SITE CPTO, commands ignore denyall “Limit WRITE”, which allows the user to copy the file to the current folder, even if he does not have such rights.
Medel emphasizes that in order to implement the remote execution of an arbitrary code on practice, must meet at once a number of conditions. assim, mod_copy must be enabled, the attacker will need access to the server (anonymous account or authorization), the server must have a file with PHP code, but not using the PHP extension, e assim por diante.
According to Shodan statistics, finalmente 28,000 potentially vulnerable servers with anonymous access and more than a million ProFTPD servers as a whole can be detected on the network.
A vulnerabilidade recebeu o identificador CVE-2019-12815 (Debian, Suse, Ubuntu) and is associated with the old bug CVE-2015-3306, which allowed an attacker to read and write arbitrary files using SITE CPFR and SITE CPTO.
Contudo, currently the problem remains uncorrected. The fact is that the patch for the problem has already been written and was added retroactively to ProFTPD 1.3.6, but the developers have not yet released a new patched version. portanto, if your package is compiled to 7.17.19, you are vulnerable. nesse caso, you can either disable mod_copy, or you should take care of downloading and recompiling.