John, a SOC analyst, while monitoring and analyzing Apache web server logs, identified an event...

 The regex pattern /(\.|(%|%25)2E)(\.|(%|%25)2E)(\/|(%|%25)2F|\\|(%|%25)5C)/i is indicative of a Directory Traversal Attack. This type of attack exploitsinsufficient security controls to gain unauthorized access to files and directories that are stored outside the web root folder. Here’s a breakdown of the regex pattern:

(\.|(%|%25)2E) matches a period . or its URL-encoded forms %2E or %252E. In file systems, a period can represent the current directory or, when used as .., the parent directory.

(\/|(%|%25)2F|\\|(%|%25)5C) matches a forward slash /, its URL-encoded form %2F or %252F, or a backslash \, which is %5C in URL encoding. These characters are used in file paths to navigate directories.

When combined, this pattern can match sequences like ../ or ..%2F, which are commonly used in directory traversal attempts to navigate up the directory tree and access files outside of the intended directory.