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#REDIRECT [[Shellcode#Alphanumeric]]
In general, in [[computing]], an '''alphanumeric code''' is a series of letters and numbers (hence the name) which are written in a form understandable and processable by a computer. One such alphanumeric code is [[ASCII]].
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More specifically, in computer underground terminology '''alphanumeric code''' is [[machine code]] that is written so that it assembles into entirely readable [[ASCII]]-letters such as "a"-"z", "A"-"Z", "1"-"9", "#", "!", "@", and so on.
This is possible to do with a (very) good understanding of the [[assembly language]] for the specific computer that the code is intended for.
This code is used by [[Cracker (computing)|cracker]]s with the intent of fooling applications, such as Web forms, into accepting code used for [[exploit (computer science)|exploit]]. Typically, such exploits involve [[buffer overflow]]s.
Sometimes, alphanumeric code could also be used when the programmer needs to write a program but does not have access to any [[compiler]] or [[assembly language|assembler]]. All that is needed to write a alphanumeric program is a [[text editor]].
==Example DOS-program==
%!!%BB-tz-!!-%cP\%!!%BB-=<PPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPPP-Written-By-Kalle-:)!!
The text above will, when interpretended by an [[x86]] [[CPU]] using the [[DOS]] operating system [[self-modifying_code|overwrite parts of itself]] with a code used to terminate the execution of the program, and return back to DOS. Just copy the text into an pure text editor (for example edit.exe in DOS or notepad in Windows), save the file and then rename it to "something.com". To execute the program, just type "something" in a DOS command shell.
[[Category:Security exploits]]
[[ca:Alfanumèric]]
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