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Re(4) (ichimunki): Security issues when allowing file upload via CGIby dmmiller2k (Chaplain) |
on Dec 07, 2001 at 01:50 UTC ( [id://130085]=note: print w/replies, xml ) | Need Help?? |
Sigh. Yes, you're right about $fn being tainted, but I was speaking more to the principle of using the standard *NIX command, "file" (or reasonable facsimile, such as the perl module File::MMagic, for example) to check the type of the file by examining the first several bytes (or more). Certainly, by the time I intended this code to run, a file would have been uploaded to some directory somewhere. My expectation was that $fn would, at the time of the call, contain the full pathname to this file, and would not necessarily have been entered directly by a web-page user. But then, I DID fail to document these expectations (read: preconditions, using programming-by-contract terminology), so I deserve to be chastised for it. (takes 40 lashes with a wet noodle) dmm You can give a man a fish and feed him for a day ... Or, you can teach him to fish and feed him for a lifetime
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