As someone who runs production services but isn't a full-time sysadmin, I evaluated this script before thinking about deploying it.
Here's what you should know:
The Good: It's a comprehensive monitoring solution that actually catches real threats. The YARA integration, eBPF monitoring, and honeypot features are impressive for a bash script.
Security Issues:
1. Command injection in process monitoring - Initially looked like a vulnerability because the code uses xargs basename on process names, which seemed dangerous. However, process names from ps output are already sanitized by the kernel (limited to 15 chars, no shell metacharacters executed).
2. Executing Python scripts from /tmp as root - Real privilege escalation vulnerability. Ghost Sentinel writes to world-writable /tmp then executes as root. Any local user can overwrite the file between write and execute to gain root. Trivial to exploit with inotify or loop, 100% reliable. Turns any compromised service account into root access. Fix: use root-owned directory instead of /tmp.
Email Configuration - Gmail will block direct server emails. Install msmtp and configure it with your Gmail app password (not regular password) to get theProtector to use msmtp's mail command:
# Install
sudo apt-get install msmtp msmtp-mta
# Configure ~/.msmtprc (for root since script runs as root)
sudo tee /root/.msmtprc << 'EOF'
defaults
auth on
tls on
tls_trust_file /etc/ssl/certs/ca-certificates.crt
account gmail
host smtp.gmail.com
port 587
from your-email@gmail.com
user your-email@gmail.com
password your-app-password
account default : gmail
EOF
sudo chmod 600 /root/.msmtprc
Auto-update concerns: The script does NOT auto-update. self_update() only runs when you explicitly execute ./the_protector.sh update
Performance note: On resource-constrained VPS instances, set ENABLE_EBPF=false and MAX_FIND_DEPTH=1
I'm deploying a patched version this week. The creator spent a year on this and it shows - the eBPF/YARA integration is impressive. They should set up GitHub Sponsors or a donation link. It's better than many commercial solutions I've seen.
> However, process names from ps output are already sanitized by the kernel (limited to 15 chars, no shell metacharacters executed).
I'm not sure what this is referring to. You can easily create a binary named ' (single quote, a shell meta character) and it will show up in ps (and /proc/pid/cmdline and /proc/pid/status) as a single quote. If you name a binary with a control character, it will show up in ps as ? (a shell metacharacter), and in /proc/$pid/cmdline and /proc/$pid/status as the control character itself (I named a binary as the single ASCII character 7, bell, and catting /proc/$pid/{cmdline,status} plays the as interpreted by the terminal program).
Recent versions of ls display these directory entries quoted for select-and-paste ease as:
$ ls -l ? # used ? here to match both files that are a single character
-rwxr-xr-x 2 thwarted thwarted 1769980 Jul 23 19:53 ''$'\a'
-rwxr-xr-x 2 thwarted thwarted 1769980 Jul 23 19:53 "'"
This was with kernel 5.14 and procps-ng-3.3.17.
Formatted by ls, the ^G file can be given to xargs, and the terminal plays a bell, but the single quote filename can not:
$ ls -1 /tmp/? | xargs -t -n 1 basename
basename '/tmp/'$'\a'
xargs: unmatched single quote; by default quotes are special to xargs unless you use the -0 option
Being able to null-byte delimit the input to xargs may make a difference here.
Anyway, you can't trust the content of what ps shows as the commandline pointing to an actual existing binary. The command line isn't always absolute. The best way to find the binary is probably by examining where the symlink /proc/$pid/exe points to, and getting the basename off of that, but that is not guaranteed to be shell-safe either, so YMMV.
Here's what you should know:
The Good: It's a comprehensive monitoring solution that actually catches real threats. The YARA integration, eBPF monitoring, and honeypot features are impressive for a bash script.
Security Issues:
1. Command injection in process monitoring - Initially looked like a vulnerability because the code uses xargs basename on process names, which seemed dangerous. However, process names from ps output are already sanitized by the kernel (limited to 15 chars, no shell metacharacters executed).
2. Executing Python scripts from /tmp as root - Real privilege escalation vulnerability. Ghost Sentinel writes to world-writable /tmp then executes as root. Any local user can overwrite the file between write and execute to gain root. Trivial to exploit with inotify or loop, 100% reliable. Turns any compromised service account into root access. Fix: use root-owned directory instead of /tmp.
Email Configuration - Gmail will block direct server emails. Install msmtp and configure it with your Gmail app password (not regular password) to get theProtector to use msmtp's mail command:
Uninstall TheProtector: Auto-update concerns: The script does NOT auto-update. self_update() only runs when you explicitly execute ./the_protector.sh updatePerformance note: On resource-constrained VPS instances, set ENABLE_EBPF=false and MAX_FIND_DEPTH=1
I'm deploying a patched version this week. The creator spent a year on this and it shows - the eBPF/YARA integration is impressive. They should set up GitHub Sponsors or a donation link. It's better than many commercial solutions I've seen.