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Jailing Apache On Windows

Yury Zaytsev wrote to me recently to tell me about his experiences in jailing Apache on Windows. Although, strictly speaking, Windows does not have the chroot system call or an equivalent it is still possible to do a pretty good job restricting its access to the system, as Yury demonstrates. From his email:

All you need is to make a local user, say, called "Apache" (you may even set him a password, don't think that makes any sense, but anyway) and deny him local and network login via group policies. Then you need to explicitly deny this user any access to the local drives (deny just everything: dir listing, read, write, modify etc), that's done via Properties - Security. Now any process spawned with "Apache"'s rights won't be able even to LIST the directories.

Now you've got to grant it the read/list folders access to the Apache Software folder (done via folder properties -> security) and write access to the PID file and log files (hopefully it doesn't need anything else).

And the last thing to do is to edit Apache's system service: you should change it's privileges via My computer - Manage workstation - Services - Apache from System service to "Apache" user (it might prompt you for the password if you've set any).

Reboot, check that Apache process is running as Apache user via the Task Manager, make sure everything is working fine and you're done.

This has also an important positive impact on the scripts security: now even if one manages to hack your poorly coded PHP/Perl script, since PHP/Perl is run via SAPI/mod_perl it couldn't list folders above Apache's root and even change any files you haven't allowed it explicitly inside Apache's root.

As you may see from above, my method is a complete rip off the Unix chroot (and chmod, he-he) technology. It's primitive and efficient (..er how efficient a Windows server can be comparing to Unixes?) Anyway it really saved my butt several times the script kiddies managed to exploit vulnerable PHP scripts.

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