How to Detect PlankFilza File System Tool, Protect iOS Apps

Last updated August 22, 2022 by Appdome

Learn to Block PlankFilza in iOS apps, in mobile CI/CD with a Data-Driven DevSecOps™ build system.

What is PlankFilza?

PlankFilza is an iOS utility or ‘tweak’ that allows access to the iOS file system/manager. Even though PlankFilza does not require the phone to be jailbroken, it is most often used in combination with Jailbreaking. This combination is used because the elevated level of privileges Jailbreaking provides enables the attacker to compromise the target app much more easily.

PlankFilza works by taking advantage of an exploit in iOS, in order to get limited read/write permissions to the iOS file system of non-jailbroken iOS devices. Once PlankFilza is installed, you can read files from any directory and write to the /var and/tmp locations.

Why Block PlankFilza in iOS Apps ?

While PlankFilza does not provide the wide range of exploits that full-fledged jailbreak techniques provide, it is still an extremely dangerous and potent challenge for security professionals. The fact that PlankFilza is often used in combination with jailbreaking is another significant reason for blocking this utility, and therefore Appdome blocks PlankFilza as part of the protection provided by enabling the Prevent Jailbreak feature.

Blocking PlankFilza on iOS apps by Using Appdome

On Appdome, follow these 3 simple steps to create self-defending iOS Apps that Block PlankFilza without an SDK or gateway:

  1. Upload the Mobile App to Appdome.

    1. Upload an app to Appdome’s Mobile App Security Build System

    2. Upload Method: Appdome Console or DEV-API
    3. iOS Formats: .ipa
  2. Build the Protection: Jailbreak Prevention.

    1. Building Jailbreak Prevention by using Appdome’s DEV-API:

      1. Create and name the Fusion Set (security template) that will contain the Jailbreak Prevention feature as shown below:
      2. fusion set that contains Jailbreak Prevention

        Figure 1: Fusion Set that will contain the Jailbreak Prevention feature
        Note: Naming the Fusion Set to correspond to the protection(s) selected is for illustration purposes only (not required).

      3. Follow the steps in Sections 2.2.1-2.2.2 of this article, Building the Jailbreak Prevention feature via Appdome Console, to add the Jailbreak Prevention feature to this Fusion Set.

      4. Open the Fusion Set Detail Summary by clicking the “...” symbol on the far-right corner of the Fusion Set, as shown in Figure 1 above, and get the Fusion Set ID from the Fusion Set Detail Summary (as shown below): fusion Set Detail Summary image

        Figure 2: Fusion Set Detail Summary
        Note: Annotating the Fusion Set to identify the protection(s) selected is optional only (not mandatory).

      5. Follow the instructions below to use the Fusion Set ID inside any standard mobile DevOps or CI/CD toolkit like Bitrise, App Center, Jenkins, Travis, Team City, Cirlce CI or other system:
        1. Build an API for the app – for instructions, see the tasks under Appdome API Reference Guide
        2. Look for sample APIs in Appdome’s GitHub Repository
    2. Building the Jailbreak Prevention feature via Appdome Console

      To build the Jailbreak Prevention protection by using Appdome Console, follow the instructions below.

      1. Where: Inside the Appdome Console, go to Build > Security Tab > OS Integrity section
      2. How: Toggle (turn ON) Jailbreak Prevention, as shown below. Jailbreak Prevention option

        Figure 3: Block PlankFilza option

      3. When you select the Jailbreak Prevention you'll notice that your Fusion Set you created in step 2.1.1 now bears the icon of the protection category that contains Jailbreak Prevention

        Fusion Set applied Jailbreak Prevention

        Figure 4: Fusion Set that displays the newly added Jailbreak Prevention protection

      4. Select the Threat-Event™ in-app mobile Threat Defense and Intelligence policy for Jailbreak Prevention:
        1. Threat-Events™ OFF > In-App Defense

          If the Threat-Events™ setting is cleared (not selected). Appdome will detect and defend the user and app by enforcing Block PlankFilza.

        2. Threat-Events™ ON > In-App Detection

          When this setting is used, Appdome detects that iOS has been compromised via jailbreaking and passes Appdome’s Threat-Event™ attack intelligence to the app’s business logic for processing, enforcement, and user notification. For more information on consuming and using Appdome Threat-Events™ in the app, see section Using Threat-Events™ for Jailbreak Prevention Intelligence and Control in Mobile Apps.

        3. Threat-Events™ ON > In-App Defense

          When this setting is used, Appdome detects and defends against PlankFilza (same as Appdome Enforce) and passes Appdome’s Threat-Event™ attack intelligence the app’s business logic for processing. For more information on consuming and using Appdome Threat-Events™ in the app, see section Using Threat-Events™ for Jailbreak Prevention Intelligence and Control in Mobile Apps.

      5. Click Build My App at the bottom of the Build Workflow (shown in Figure 3).
    Congratulations!  The Jailbreak Prevention protection is now added to the mobile app
  3. Certify the Jailbreak Prevention feature in iOS Apps.

    After building Jailbreak Prevention, Appdome generates a Certified Secure™ certificate to guarantee that the Jailbreak Prevention protection has been added and is protecting the app. To verify that the Jailbreak Prevention protection has been added to the mobile app, locate the protection in the Certified Secure™ certificate as shown below: Jailbreak Prevention shown in Certificate secure

    Figure 5: Certified Secure™ certificate

    Each Certified Secure™ certificate provides DevOps and DevSecOps organizations the entire workflow summary, audit trail of each build, and proof of protection that Jailbreak Prevention has been added to each iOS app. Certified Secure provides instant and in-line DevSecOps compliance certification that Jailbreak Prevention and other mobile app security features are in each build of the mobile app

Using Threat-Events™ for PlankFilza Intelligence and Control in iOS Apps

Appdome Threat-Events™ provides consumable in-app mobile app attack intelligence and defense control when PlankFilza is detected. To consume and use Threat-Events™ for PlankFilza in iOS Apps, use AddObserverForName in Notification Center, and the code samples for Threat-Events™ for PlankFilza shown below.

The specifications and options for Threat-Events™ for PlankFilza are:

Threat-Event™ Elements Block PlankFilza Method Detail
Appdome Feature Name Jailbreak Prevention
Threat-Event Mode
OFF, IN-APP DEFENSE Appdome detects, defends and notifies user (standard OS dialog) using customizable messaging.
ON, IN-APP DETECTON Appdome detects the attack or threat and passes the event in a standard format to the app for processing (app chooses how and when to enforce).
ON, IN-APP DEFENSE Uses Appdome Enforce mode for any attack or threat and passes the event in a standard format to the app for processing (gather intel on attacks and threats without losing any protection).
Certified Secure™ Threat Event Check
Visible in ThreatScope™
Developer Parameters for Blocking PlankFilza Threat-Event™
Threat-Event NAME JailbrokenDevice
Threat-Event DATA reasonData
Threat-Event CODE reasonCode
Threat-Event REF 6901
Threat-Event SCORE
currentThreatEventScore Current Threat-Event score
threatEventsScore Total Threat-events score
Threat-Event Context Keys
messageMessage displayed for the user on event
externalIDThe external ID of the event which can be listened via Threat Events
osVersionOS version of the current device
deviceModelCurrent device model
deviceManufacturerThe manufacturer of the current device
fusedAppTokenThe task ID of the Appdome fusion of the currently running app
kernelInfoInfo about the kernel: system name, node name, release, version and machine.
carrierPlmnPLMN of the device
deviceIDCurrent device ID
reasonCodeReason code of the occured event
buildDateAppdome fusion date of the current application
devicePlatformOS name of the current device
carrierNameCarrier name of the current device
updatedOSVersionIs the OS version up to date
timeZoneTime zone
deviceFaceDownIs the device face down
locationLongLocation long
locationLatLocation lat
locationStateLocation state
wifiSsidWifi SSID
wifiSsidPermissionStatusWifi SSID permission status
internalErrorInternal error code as hex
extendedMessageTextInternal error code
rInternalErrorCodeInternal error code
reasonReason for the root detection

With Threat-Events™ enabled (turned ON), iOS developers can get detailed attack intelligence and granular defense control in iOS applications and create amazing user experiences for all mobile end users when PlankFilza is detected.

The following is a code sample for native iOS apps, which uses all values in the specification above for Jailbreak Prevention:

Prerequisites to Using Jailbreak Prevention:

To use Appdome’s mobile app security build system to Block PlankFilza , you’ll need:

Using Appdome, there are no development or coding prerequisites to build secured Apps by using Jailbreak Prevention. There is no SDK and no library to code or implement in the app and no gateway to deploy in your network. All protections are built into each app and the resulting app is self-defending and self-protecting.

Releasing and Publishing Mobile Apps with Jailbreak Prevention

After successfully securing your app by using Appdome, there are several available options to complete your project, depending on your app lifecycle or workflow. These include:

All apps protected by Appdome are fully compatible with any public app store, including Apple App Store, Google Play, Huawei App Gallery and more.

Protections Similar to Jailbreak Prevention

Here are a few related resources:

Jailbreaking Prevention

Rooting Android 

Prevent Jailbreak Bypass and Jailbreak Hiding 

How to Protect iOS Apps Against FlyJB Jailbreak Bypass

 

If you have any questions, please send them our way at support.appdome.com or via the chat window on the Appdome platform.

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