😤I Had Write Permissions... So Why Was Linux Saying "No"?
🧠 “If I have write access to a file, I should be able to write to it… right?”
That’s what I thought. Until Linux roundhouse kicked me in the brain.
🎯 The Setup — HTB: Traverxec
I was knee-deep in the Traverxec box on Hack The Box. You know, that one with some misconfigured nostromo web server and a classic privilege escalation path. Things were going smoothly. Too smooth.
I landed a shell as david. Did some recon. Crawled into the /home/david/bin directory — jackpot.
I found a file:
Looked promising. Maybe some crontab magic? Maybe I can inject a command and get root? Let’s gooo.
I checked permissions:
Full permissions. Owned by me. Hell yeah.
I tried a quick test:
💥 BOOM. No wait. Not boom. Smack.
🧪 Sanity Check
Hold up. I checked again:
✅ File owned by
david✅
rwxpermissions✅ I'm logged in as
david❌ Can't write, rename, delete, chmod, or even
echointo it
It felt like I was trying to write to a ghost.
🔍 The Sherlock Moment (aka: Googling Like a Madman)
At this point, I was questioning everything. My permissions were correct. I owned the file. The command syntax was fine. So why the hell was Linux stonewalling me?
So, I did what any respectable hacker does in a crisis: I Googled. Hard.
And after sifting through a dozen StackOverflow posts, some outdated forums, and a Reddit thread titled “WTF is this i thing in lsattr?” — I had my answer.
I found out about lsattr, a command that shows file attributes at the filesystem level, not just the usual ls -la stuff.
I ran:
And there it was, hiding in plain sight:
That i stands for immutable.
This little gremlin of a flag meant the file was locked down so hard that even root couldn’t touch it without removing the bit first.
It was like Linux was saying:
"Oh, you thought you were in charge? That’s cute."
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