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Thanks for the details. I didn't know Ubuntu was restricting ptrace by default now. Now I need to figure out how to do that on my Debian system -- it definitely

Thanks for the details. I didn't know Ubuntu was restricting ptrace by default now. Now I need to figure out how to do that on my Debian system -- it definitely allows me to gdb attach to an unrelated process presently. Even that protection doesn't seem to make it safe to run untrusted programs under the same UID, though? If nothing else, there's always the classic "modify user's rc files to put my malicious program first in $PATH." Similarly you could modify them to increase the core file size rlimit, then send SIGSEGV to the process later and collect the core file.

nicce 5y ago
> Now I need to figure out how to do that on my Debian system -- it definitely allows me to gdb attach to an unrelated process presently. You could try to set it similarly than Ubuntu is doing. See Yama kernel module [1], and set mode 1 (restricted). > Even that protection doesn't seem to make it safe to run untrusted programs under the same UID, though? If nothing else, there's always the classic "modify user's rc files to put my malicious program first in $PATH." Similarly you could modify them to increase the core file size rlimit, then send SIGSEGV to the process later and collect the core file. AppArmor[2] is useful for this, you could define profile for the untrusted app, and it cannot access any other file than you allow. [1]: https://www.kernel.org/doc/html/latest/admin-guide/LSM/Yama.html https://www.kernel.org/doc/html/latest/admin-guide/LSM/Yama.... [2]: https://www.kernel.org/doc/html/latest/admin-guide/LSM/apparmor.html https://www.kernel.org/doc/html/latest/admin-guide/LSM/appar...