MacOS Security & Privilege Escalation

First of all, please note that most of the tricks about privilege escalation affecting Linux/Unix will affect also MacOS machines. So see:

{% page-ref page="../linux-unix/privilege-escalation/" %}

Security Restrictions

Gatekeeper

Gatekeeper is designed to ensure that, by default, only trusted software runs on a user’s Mac. Gatekeeper is used when a user downloads and opens an app, a plug-in or an installer package from outside the App Store. Gatekeeper verifies that the software is from an identified developer, is notarised by Apple to be free of known malicious content, and hasn’t been altered. Gatekeeper also requests user approval before opening downloaded software for the first time to make sure the user hasn’t been tricked into running executable code they believed to simply be a data file.

Gatekeeper builds upon File Quarantine.
Upon download of an application, a particular extended file attribute "quarantine flag" can be added to the downloaded file. This attribute is added by the application that downloads the file, such as a web browser or email client, but is not usually added by others like common BitTorrent client software.
When a user executes a "quarentined" file, Gatekeeper is the one that performs the mentioned actions to allow the execution of the file.

It's possible to check it's status and enable/disable root required with:

spctl --status
assessments enabled

spctl --enable
spctl --disable
#You can also allow nee identifies to execute code using the binary "spctl"

You can also find if a file has the quarantine extended attribute with:

xattr portada.png
com.apple.macl
com.apple.quarantine

Check the value of the extended attributes with:

xattr -l portada.png
com.apple.macl:
00000000  03 00 53 DA 55 1B AE 4C 4E 88 9D CA B7 5C 50 F3  |..S.U..LN.....P.|
00000010  16 94 03 00 27 63 64 97 98 FB 4F 02 84 F3 D0 DB  |....'cd...O.....|
00000020  89 53 C3 FC 03 00 27 63 64 97 98 FB 4F 02 84 F3  |.S....'cd...O...|
00000030  D0 DB 89 53 C3 FC 00 00 00 00 00 00 00 00 00 00  |...S............|
00000040  00 00 00 00 00 00 00 00                          |........|
00000048
com.apple.quarantine: 0081;607842eb;Brave;F643CD5F-6071-46AB-83AB-390BA944DEC5

And remove that attribute with:

xattr -d com.apple.quarantine portada.png
#You can also remove this attribute from every file with
find . -iname '*' -print0 | xargs -0 xattr -d com.apple.quarantine

And find all the quarantined files with:

find / -exec ls -ld {} \; 2>/dev/null | grep -E "[x\-]@ " | awk '{printf $9; printf "\n"}' | xargs -I {} xattr -lv {} | grep "com.apple.quarantine"

Common users

Daemon: User reserved for system daemons
Guest: Account for guests with very strict permissions
Nobody: Processes are executed with this user when minimal permissions are required
Root

File ACLs

When the file contains ACLs you will find a "+" when listing the permissions like in:

ls -ld Movies
drwx------+   7 username  staff     224 15 Apr 19:42 Movies

You can read the ACLs of the file with:

ls -lde Movies
drwx------+ 7 username  staff  224 15 Apr 19:42 Movies
 0: group:everyone deny delete

You can find all the files with ACLs with this is veeery slow:

ls -RAle / 2>/dev/null | grep -E -B1 "\d: "

Resource Forks or MacOS ADS

This is a way to obtain Alternate Data Streams in MacOS machines. You can save content inside an extended attribute called com.apple.ResourceFork inside a file by saving it in file/..namedfork/rsrc.

echo "Hello" > a.txt
echo "Hello Mac ADS" > a.txt/..namedfork/rsrc

xattr -l a.txt #Read extended attributes
com.apple.ResourceFork: Hello Mac ADS

ls -l a.txt #The file length is still q
-rw-r--r--@ 1 username  wheel  6 17 Jul 01:15 a.txt

You can find all the files containing this extended attribute with:

find / -type f -exec ls -ld {} \; 2>/dev/null | grep -E "[x\-]@ " | awk '{printf $9; printf "\n"}' | xargs -I {} xattr -lv {} | grep "com.apple.ResourceFork"

OS X Specific Extensions

.dmg: Apple Disk Image files are very frequent for installers.
.kext: It must follow a specific structure and it's the OS X version of a driver.
.plist: Also known as property list stores information in XML or binary format.
.app: Apple applications that follows directory structure.
.dylib: Dynamic libraries like Windows DLL files
.pkg: Are the same as xar eXtensible Archive format. The installer command can be use to install the contents of these files.

File hierarchy layout

/Applications: The installed apps should be here. All the users will be able to access them.
/bin: Command line binaries
/cores: If exists, it's used to store core dumps
/dev: Everything is treated as a file so you may see hardware devices stored here.
/etc: Configuration files
/Library: A lot of subdirectories and files related to preferences, caches and logs can be found here. A Library folder exists in root and on each user's directory.
/private: Undocumented but a lot of the mentioned folders are symbolic links to the private directory.
/sbin: Essential system binaries related to administration
/System: File fo making OS X run. You should find mostly only Apple specific files here not third party.
/tmp: Files are deleted after 3 days it's a soft link to /private/tmp
/Users: Home directory for users.
/usr: Config and system binaries
/var: Log files
/Volumes: The mounted drives will apear here.
/.vol: Running stat a.txt you obtain something like 16777223 7545753 -rw-r--r-- 1 username wheel ... where the first number is the id number of the volume where the file exists and the second one is the inode number. You can access the content of this file through /.vol/ with that information running cat /.vol/16777223/7545753

Special MacOS files and folders

.DS_Store: This file is on each directory, it saves the attributes and customisations of the directory.
.Spotlight-V100: This folder appears on the root directory of every volume on the system.
.metadata_never_index: If this file is at the root of a volume Spotlight won't index that volume.
<name>.noindex: Files and folder with this extension won't be indexed by Spotlight.
**$HOME/Library/Preferences/com.apple.LaunchServices.QuarantineEventsV**2: Contains information about downloaded files, like the URL from where they were downloaded.

Specific MacOS Enumeration

smbutil statshares -a #View smb shares mounted to the hard drive
launchctl list #List services
atq #List "at" tasks for the user
mdfind password #Show all the files that contains the word password
mfind -name password #List all the files containing the word password in the name
sysctl -a #List kernel configuration
diskutil list #List connected hard drives
codesign -vv -d /bin/ls #Check the signature of a binary
nettop #Monitor network usage of processes in top style

#security
secuirty dump-trust-settings [-s] [-d] #List certificates
security list-keychains #List keychain dbs
security list-smartcards #List smartcards
security dump-keychain | grep -A 5 "keychain" | grep -v "version" #List keychains entries
security dump-keychain -d #Dump all the info, included secrets (the user will be asked for his password, even if root)



#networksetup - set or view network options: Proxies, FW options and more
networksetup -listallnetworkservices #List network services
networksetup -listallhardwareports #Hardware ports
networksetup -getinfo Wi-Fi #Wi-Fi info
networksetup -getautoproxyurl Wi-Fi #Get proxy URL for Wifi
networksetup -getwebproxy Wi-Fi #Wifi Web proxy
networksetup -getftpproxy Wi-Fi #Wifi ftp proxy

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