Webshells remain a popular method for attackers to maintain persistence on a compromised web server. Many "arbitrary file write" and "remote code execution" vulnerabilities are used to drop small files on systems for later execution of additional payloads. The names of these files keep changing and are often chosen to "fit in" with other files. Webshells themselves are also often used by parasitic attacks to compromise a server. Sadly (?), attackers are not always selecting good passwords either. In some cases, webshells come with pre-set backdoor credentials, which may be overlooked by a less sophisticated attacker.