Twenty Year Anniversary

Apple macOS 10.13.1 High Sierra Cron Privilege Escalation

Apple macOS 10.13.1 High Sierra Cron Privilege Escalation
Posted Dec 7, 2017
Authored by Mark Wadham

Apple macOS version 10.13.1 (High Sierra) suffers from a cron related local privilege escalation vulnerability that allows you to gain root privileges.

tags | exploit, local, root
systems | apple
MD5 | 9473afa208319a6ea6560b35916c5529

Apple macOS 10.13.1 High Sierra Cron Privilege Escalation

Change Mirror Download
Recently I was working on an security issue in some other software that has yet to be disclosed which created a rather interesting condition. As a non-root user I was able to write to any file on the system that was not SIP-protected but the resulting file would not be root-owned, even if it previously was.

This presented an interesting challenge for privilege escalation - how would you exploit this to obtain root access? The obvious first attempt was the sudoers file but sudo is smart enough not to process it if the file isn't root-owned so that didn't work.

I then discovered (after a tip from a friend - thanks pndc!) that the cron system in macOS does not care who the crontab files are owned by. Getting root was a simple case of creating a crontab file at:

```
/var/at/tabs/root
```

with a 60-second cron line, eg:

```
* * * * * chown root:wheel /tmp/payload && chmod 4755 /tmp/payload
```

and then waiting for it to execute. It's not clear if this is a macOS-specific issue or a hangover from the BSD-inherited cron system, I suspect the latter.

The issue has been reported to Apple so hopefully they will fix it.

Comments

RSS Feed Subscribe to this comment feed

No comments yet, be the first!

Login or Register to post a comment

Want To Donate?


Bitcoin: 18PFeCVLwpmaBuQqd5xAYZ8bZdvbyEWMmU

File Archive:

April 2018

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Apr 1st
    5 Files
  • 2
    Apr 2nd
    17 Files
  • 3
    Apr 3rd
    11 Files
  • 4
    Apr 4th
    21 Files
  • 5
    Apr 5th
    17 Files
  • 6
    Apr 6th
    12 Files
  • 7
    Apr 7th
    1 Files
  • 8
    Apr 8th
    6 Files
  • 9
    Apr 9th
    21 Files
  • 10
    Apr 10th
    18 Files
  • 11
    Apr 11th
    42 Files
  • 12
    Apr 12th
    7 Files
  • 13
    Apr 13th
    14 Files
  • 14
    Apr 14th
    1 Files
  • 15
    Apr 15th
    1 Files
  • 16
    Apr 16th
    15 Files
  • 17
    Apr 17th
    20 Files
  • 18
    Apr 18th
    24 Files
  • 19
    Apr 19th
    20 Files
  • 20
    Apr 20th
    7 Files
  • 21
    Apr 21st
    10 Files
  • 22
    Apr 22nd
    0 Files
  • 23
    Apr 23rd
    0 Files
  • 24
    Apr 24th
    0 Files
  • 25
    Apr 25th
    0 Files
  • 26
    Apr 26th
    0 Files
  • 27
    Apr 27th
    0 Files
  • 28
    Apr 28th
    0 Files
  • 29
    Apr 29th
    0 Files
  • 30
    Apr 30th
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2018 Packet Storm. All rights reserved.

Services
Security Services
Hosting By
Rokasec
close