Website Security : Command Injection
Another dangerous activity is executing shell commands whereby the user has supplied a part of the command. Mitigating this risk is very similar to mitigating the risk of SQL injection, although there are some specific PHP functions that you should learn. With properly filtered data, there are only two potential problems that you might
encounter regarding shell commands:
1. There might be metacharacters that can be used to execute arbitrary commands.
2. If the data being used to construct a command is intended to be a single argument, there might be characters within the data that cause it to be interpreted as multiple arguments instead.
These problems are solved with escapeshellcmd() and escapeshellarg(), respectively. Data passed through escapeshellcmd() will be escaped such that it no longer poses a risk of arbitrary shell command execution. Data passed through escapeshellarg() can safely be used as a single argument.
SOURCE:ZEND PHP5 CERTIFICATION STUDY GUIDE
encounter regarding shell commands:
1. There might be metacharacters that can be used to execute arbitrary commands.
2. If the data being used to construct a command is intended to be a single argument, there might be characters within the data that cause it to be interpreted as multiple arguments instead.
These problems are solved with escapeshellcmd() and escapeshellarg(), respectively. Data passed through escapeshellcmd() will be escaped such that it no longer poses a risk of arbitrary shell command execution. Data passed through escapeshellarg() can safely be used as a single argument.
SOURCE:ZEND PHP5 CERTIFICATION STUDY GUIDE
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