1.3 KiB
Execution/Compiliation/Verification Workers
Submitted assignments for C/C++ but also many otehr languages need to be build or compiled before you can run them. Finally the submitted solutios shall be verified automatically to some extend.
Execution of Untrusted Code
The general problem here is to provide a safe environment that jails the program into a sandbox leaving the rest of the system inpenetrable. This is considered generally NOT possible in practice as exploits can exist in any complex systems.
These opportunities to exploit the system are especially given when lower levels are used. C code generally offers a wider range of possible attacks. Besides a planned attack on a system, systems may be brought down also by accident.
- DOS of the Test Environment (CPU, RAM, Network..)
- Fork-Bombs
Mitigation Measures
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Dedicated Hardware on a seperate Network
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Virtual Machines
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Containers (e.g. Docker, LXC)
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Apparmor / SE Linux
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Limit resources (CPU, RAM, Disk, Network)
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lower nice values to keep system responsive
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Filesystem Privileges
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"least privelege"
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cgroups
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chroot - http://www.bpfh.net/simes/computing/chroot-break.html
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only a very reduced tool chain
http://blog.remoteinterview.io/post/89639823776/how-we-used-docker-to-compile-and-run-untrusted http://hmarr.com/2013/oct/16/codecube-runnable-gists/