173 lines
3.3 KiB
HTML
173 lines
3.3 KiB
HTML
<HTML
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>Call Only Interfaces Intended for Programmers</TITLE
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NAME="CALL-INTENTIONAL-APIS"
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>8.4. Call Only Interfaces Intended for Programmers</H1
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><P
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>Call only application programming interfaces (APIs) that are
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intended for use by programs.
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Usually a program can invoke any other program,
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including those that are really designed for human interaction.
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However, it's usually unwise to invoke a program intended for human
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interaction in the same way a human would.
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The problem is that programs's human interfaces are intentionally rich
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in functionality and are often difficult to completely control.
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As discussed in <A
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HREF="handle-metacharacters.html"
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>Section 8.3</A
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>,
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interactive programs often have ``escape'' codes,
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which might enable an attacker to perform undesirable functions.
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Also, interactive programs often try to intuit the ``most likely'' defaults;
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this may not be the default you were expecting, and an attacker may find
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a way to exploit this.</P
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><P
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>Examples of programs you shouldn't normally call directly include
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mail, mailx, ed, vi, and emacs.
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At the very least, don't call these without checking
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their input first.</P
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><P
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>Usually there are parameters to give you safer access to the program's
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functionality,
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or a different API or application that's intended for use by programs;
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use those instead.
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For example, instead of invoking a text editor to edit some text
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(such as ed, vi, or emacs), use sed where you can.</P
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