Apple this afternoon published a new support document that walks users through repairing their file sharing options on their Macs after installing the 2017-001 Security Update for macOS High Sierra 10.13.1, which was released this morning.
Shortly after the security fix was released and users began installing it, file sharing complaints began surfacing on the MacRumors forums. Affected users saw file sharing fail to authenticate across multiple Macs. From MacRumors reader joedec:
Immediately after installing this patch, file sharing fails to authenticate. I see this on multiple Macs. Hoping for some collaboration. [...]
With the Finder open a file share to any Mac with the security update installed. Status shows "not connected", when you try to "connect as" your username and password fail.
According to the document, macOS High Sierra users who cannot access file sharing after installing the security update will need to complete the following steps:
1. Open the Terminal app, which is in the Utilities folder of your Applications folder.
2. Type sudo /usr/libexec/configureLocalKDC and press Return.
3. Enter your administrator password and press Return.
4. Quit the Terminal app.
MacRumors readers who were having file sharing problems have tested Apple's fix and have confirmed that it does indeed work to solve the problem.
Apple issued this morning's security update to address a major vulnerability that enabled the root superuser on a Mac with a blank password and no security check.
The problem has been successfully fixed on machines running macOS High Sierra 10.13.1, the current release version of macOS High Sierra, but Apple has not yet addressed the vulnerability in macOS High Sierra 10.13.2, available to both developers and public beta testers.
Update: Apple appears to have released a revised version of the security update, which is valid for systems running both macOS 10.13.0 and 10.13.1. The revised version may also address the issue in the original version that resulted in file sharing problems.
