41 (Weakness Class)

File/Directory

Assume all input is malicious. Attackers can insert special characters into resources (e.g. filenames) to disguise their input. Use an appropriate combination of black lists and white lists to ensure only valid and expected input is processed by the system. Warning: if you attempt to cleanse your data, then do so that the end result is not in the form that can be dangerous. A sanitizing mechanism can remove characters such as ‘.' and ‘;' which may be required for some exploits. An attacker can try to fool the sanitizing mechanism into "cleaning" data into a dangerous form. Suppose the attacker injects a ‘.' inside a filename (e.g. "sensi.tiveFile") and the sanitizing mechanism removes the character resulting in the valid filename, "sensitiveFile". If the input data are now assumed to be safe, then the file may be compromised.

Some of these manipulations could be effective in path traversal issues, too.

PLOVER - Path Equivalence

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