Unicodeban

Unicodeban refers to a phenomenon where certain characters or sequences of characters within the Unicode standard are intentionally avoided or filtered by software, operating systems, or network protocols. This avoidance is typically done to prevent security vulnerabilities, rendering issues, or unintended interpretations of data.

One common reason for Unicodeban is the exploitation of how different systems parse or interpret Unicode. For example, certain characters might be used in attacks to bypass input validation filters or to inject malicious code. Developers might choose to ban these characters to mitigate such risks. Another reason relates to character encoding conversions. Inconsistent handling of Unicode across different platforms or applications can lead to data corruption or display errors. Banning problematic characters, especially those outside the common multilingual plane, can sometimes be a pragmatic solution.

Furthermore, some characters, particularly those with combining diacritical marks or those that can be visually ambiguous with ASCII characters, may be banned to prevent "homograph attacks" where malicious actors try to impersonate legitimate URLs or identifiers. The implementation of Unicodeban can vary widely. Some systems might implement strict blacklists, while others may rely on more sophisticated heuristics to detect potentially harmful sequences. The ongoing evolution of Unicode and the discovery of new vulnerabilities mean that the practice of Unicodeban is a dynamic and evolving aspect of software security and data handling.