security.variables.html
来自「php的帮助文档,涉及到PHP的案例和基本语法,以及实际应用内容」· HTML 代码 · 共 88 行
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>User Submitted Data</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="security.globals.html">Using Register Globals</a></div> <div class="next" style="text-align: right; float: right;"><a href="security.magicquotes.html">Magic Quotes</a></div> <div class="up"><a href="security.html">Security</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div> <h1>User Submitted Data</h1> <p class="para"> The greatest weakness in many PHP programs is not inherent in the language itself, but merely an issue of code not being written with security in mind. For this reason, you should always take the time to consider the implications of a given piece of code, to ascertain the possible damage if an unexpected variable is submitted to it. <div class="example"> <p><b>Example #1 Dangerous Variable Usage</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// remove a file from the user's home directory... or maybe<br />// somebody else's?<br /></span><span style="color: #0000BB">unlink </span><span style="color: #007700">(</span><span style="color: #0000BB">$evil_var</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Write logging of their access... or maybe an /etc/passwd entry?<br /></span><span style="color: #0000BB">fwrite </span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #0000BB">$evil_var</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Execute something trivial.. or rm -rf *?<br /></span><span style="color: #0000BB">system </span><span style="color: #007700">(</span><span style="color: #0000BB">$evil_var</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">exec </span><span style="color: #007700">(</span><span style="color: #0000BB">$evil_var</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> <p class="para"> You should always carefully examine your code to make sure that any variables being submitted from a web browser are being properly checked, and ask yourself the following questions: <ul class="itemizedlist"> <li class="listitem"> <span class="simpara"> Will this script only affect the intended files? </span> </li> <li class="listitem"> <span class="simpara"> Can unusual or undesirable data be acted upon? </span> </li> <li class="listitem"> <span class="simpara"> Can this script be used in unintended ways? </span> </li> <li class="listitem"> <span class="simpara"> Can this be used in conjunction with other scripts in a negative manner? </span> </li> <li class="listitem"> <span class="simpara"> Will any transactions be adequately logged? </span> </li> </ul> </p> <p class="para"> By adequately asking these questions while writing the script, rather than later, you prevent an unfortunate re-write when you need to increase your security. By starting out with this mindset, you won't guarantee the security of your system, but you can help improve it. </p> <p class="para"> You may also want to consider turning off register_globals, magic_quotes, or other convenience settings which may confuse you as to the validity, source, or value of a given variable. Working with PHP in error_reporting(E_ALL) mode can also help warn you about variables being used before they are checked or initialized (so you can prevent unusual data from being operated upon). </p></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="security.globals.html">Using Register Globals</a></div> <div class="next" style="text-align: right; float: right;"><a href="security.magicquotes.html">Magic Quotes</a></div> <div class="up"><a href="security.html">Security</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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