Tagged
#filesystem
4 posts
A CTF Against My Own Kernel
I proved my toy filesystem would leak a hidden flag if you handed it a forged disk image — then turned that private, one-shot proof into a browser CTF you can play. Here's the bug, and the delivery engineering it took to let anyone throw the switch.
ReadAttacking the Lies About Disk Layout
A flag hidden in the RAM disk with no name, a crafted directory entry that reads it right out, and the one-field fix that turns 'in the image' into 'in the data.' A bounds check is only as trustworthy as the bound it compares against.
ReadThe whole point, arrived at
Subdirectories, cd/pwd/ls/cat, and the moment the core arc — boot, memory, tasks, shell, files — is complete. Along the way I learned the hard way that a termination proof is not a safety proof: my validator provably terminated and still hid two denial-of-service bugs.
ReadFiles are just convincing lies about disk layout
I built a read-only filesystem for my from-scratch kernel, and the lesson is what a 'file' actually is: a directory table of {name, offset, length} over a flat run of bytes. The hard, security-relevant code isn't the reading — it's the refusing.
Read