Apple macOS 10.13.1 (High Sierra) - 'Blank Root' Local Privilege Escalation

EDB-ID: 43248
Author: Lemiorhan
Published: 2017-11-28
CVE: CVE-2017-13872
Type: Local
Platform: macOS
Aliases: N/A
Advisory/Source: Link
Tags: N/A
Vulnerable App: N/A

 "Dear @AppleSupport, we noticed a *HUGE* security issue at MacOS High Sierra. Anyone can login as "root" with empty password after clicking on login button several times. Are you aware of it @Apple?" 


## Proof: https://twitter.com/patrickwardle/status/935608904377077761


## Mitigation/Detection/Forensic: https://news.ycombinator.com/item?id=15800676
- Can be mitigated by enabling the root user with a strong password
- Can be detected with `osquery` using `SELECT * FROM plist WHERE path = "/private/var/db/dslocal/nodes/Default/users/root.plist" AND key = "passwd" AND length(value) > 1;";`
- You can see what time the root account was enabled using `SELECT * FROM plist WHERE path = "/private/var/db/dslocal/nodes/Default/users/root.plist" WHERE key = "accountPolicyData";` then base 64 decoding that into a file and then running `plutil -convert xml1` and looking at the `passwordLastSetTime` field.
_Note: osquery needs to be running with `sudo` but if you have it deployed across a fleet of macs as a daemon then it will be running with `sudo` anyway._
_Note: You can get the same info with plutil(1): `$ sudo plutil -p /private/var/db/dslocal/nodes/Default/users/root.plist`_


## Security Advisory: https://support.apple.com/en-gb/HT208315

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