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HackTricks - Boitatech
  • HackTricks
  • About the author
  • Getting Started in Hacking
  • Pentesting Methodology
  • External Recon Methodology
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    • Checklist - Linux Privilege Escalation
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  • MacOS
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  • Windows
    • Checklist - Local Windows Privilege Escalation
    • Windows Local Privilege Escalation
      • AppendData/AddSubdirectory permission over service registry
      • Create MSI with WIX
      • DPAPI - Extracting Passwords
      • SeImpersonate from High To System
      • Access Tokens
      • ACLs - DACLs/SACLs/ACEs
      • Dll Hijacking
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      • JAWS
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      • MSI Wrapper
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      • PowerUp
      • Privilege Escalation Abusing Tokens
      • Privilege Escalation with Autoruns
      • RottenPotato
      • Seatbelt
      • SeDebug + SeImpersonate copy token
      • Windows C Payloads
    • Active Directory Methodology
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      • AD information in printers
      • ASREPRoast
      • BloodHound
      • Constrained Delegation
      • Custom SSP
      • DCShadow
      • DCSync
      • DSRM Credentials
      • Golden Ticket
      • Kerberos Authentication
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      • MSSQL Trusted Links
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      • Password Spraying
      • Force NTLM Privileged Authentication
      • Privileged Accounts and Token Privileges
      • Resource-based Constrained Delegation
      • Security Descriptors
      • Silver Ticket
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    • NTLM
      • Places to steal NTLM creds
      • PsExec/Winexec/ScExec
      • SmbExec/ScExec
      • WmicExec
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    • Stealing Credentials
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    • Authentication, Credentials, UAC and EFS
    • Basic CMD for Pentesters
    • Basic PowerShell for Pentesters
      • PowerView
    • AV Bypass
  • Mobile Apps Pentesting
    • Android APK Checklist
    • Android Applications Pentesting
      • Android Applications Basics
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      • APK decompilers
      • AVD - Android Virtual Device
      • Burp Suite Configuration for Android
      • content:// protocol
      • Drozer Tutorial
        • Exploiting Content Providers
      • Exploiting a debuggeable applciation
      • Frida Tutorial
        • Frida Tutorial 1
        • Frida Tutorial 2
        • Frida Tutorial 3
        • Objection Tutorial
      • Google CTF 2018 - Shall We Play a Game?
      • Inspeckage Tutorial
      • Intent Injection
      • Make APK Accept CA Certificate
      • Manual DeObfuscation
      • React Native Application
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      • Smali - Decompiling/[Modifying]/Compiling
      • Spoofing your location in Play Store
      • Webview Attacks
    • iOS Pentesting Checklist
    • iOS Pentesting
      • Basic iOS Testing Operations
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      • Extracting Entitlements From Compiled Application
      • Frida Configuration in iOS
      • iOS App Extensions
      • iOS Basics
      • iOS Custom URI Handlers / Deeplinks / Custom Schemes
      • iOS Hooking With Objection
      • iOS Protocol Handlers
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  • Pentesting
    • Pentesting Network
      • Spoofing LLMNR, NBT-NS, mDNS/DNS and WPAD and Relay Attacks
      • Spoofing SSDP and UPnP Devices with EvilSSDP
      • Wifi Attacks
        • Evil Twin EAP-TLS
      • Pentesting IPv6
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    • Pentesting JDWP - Java Debug Wire Protocol
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    • Pentesting SAP
    • Pentesting Kubernetes
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    • 7/tcp/udp - Pentesting Echo
    • 21 - Pentesting FTP
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      • FTP Bounce - Download 2ºFTP file
    • 22 - Pentesting SSH/SFTP
    • 23 - Pentesting Telnet
    • 25,465,587 - Pentesting SMTP/s
      • SMTP - Commands
    • 43 - Pentesting WHOIS
    • 53 - Pentesting DNS
    • 69/UDP TFTP/Bittorrent-tracker
    • 79 - Pentesting Finger
    • 80,443 - Pentesting Web Methodology
      • 403 & 401 Bypasses
      • AEM - Adobe Experience Cloud
      • Apache
      • Artifactory Hacking guide
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      • PHP Tricks (SPA)
        • PHP - Useful Functions & disable_functions/open_basedir bypass
          • disable_functions bypass - php-fpm/FastCGI
          • disable_functions bypass - dl function
          • disable_functions bypass - PHP 7.0-7.4 (*nix only)
          • disable_functions bypass - Imagick <= 3.3.0 PHP >= 5.4 Exploit
          • disable_functions - PHP 5.x Shellshock Exploit
          • disable_functions - PHP 5.2.4 ionCube extension Exploit
          • disable_functions bypass - PHP <= 5.2.9 on windows
          • disable_functions bypass - PHP 5.2.4 and 5.2.5 PHP cURL
          • disable_functions bypass - PHP safe_mode bypass via proc_open() and custom environment Exploit
          • disable_functions bypass - PHP Perl Extension Safe_mode Bypass Exploit
          • disable_functions bypass - PHP 5.2.3 - Win32std ext Protections Bypass
          • disable_functions bypass - PHP 5.2 - FOpen Exploit
          • disable_functions bypass - via mem
          • disable_functions bypass - mod_cgi
          • disable_functions bypass - PHP 4 >= 4.2.0, PHP 5 pcntl_exec
      • Python
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      • Spring Actuators
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      • Uncovering CloudFlare
      • VMWare (ESX, VCenter...)
      • Web API Pentesting
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      • werkzeug
      • Wordpress
      • XSS to RCE Electron Desktop Apps
    • 88tcp/udp - Pentesting Kerberos
      • Harvesting tickets from Windows
      • Harvesting tickets from Linux
    • 110,995 - Pentesting POP
    • 111/TCP/UDP - Pentesting Portmapper
    • 113 - Pentesting Ident
    • 123/udp - Pentesting NTP
    • 135, 593 - Pentesting MSRPC
    • 137,138,139 - Pentesting NetBios
    • 139,445 - Pentesting SMB
    • 143,993 - Pentesting IMAP
    • 161,162,10161,10162/udp - Pentesting SNMP
      • SNMP RCE
    • 194,6667,6660-7000 - Pentesting IRC
    • 264 - Pentesting Check Point FireWall-1
    • 389, 636, 3268, 3269 - Pentesting LDAP
    • 500/udp - Pentesting IPsec/IKE VPN
    • 502 - Pentesting Modbus
    • 512 - Pentesting Rexec
    • 513 - Pentesting Rlogin
    • 514 - Pentesting Rsh
    • 515 - Pentesting Line Printer Daemon (LPD)
    • 548 - Pentesting Apple Filing Protocol (AFP)
    • 554,8554 - Pentesting RTSP
    • 623/UDP/TCP - IPMI
    • 631 - Internet Printing Protocol(IPP)
    • 873 - Pentesting Rsync
    • 1026 - Pentesting Rusersd
    • 1080 - Pentesting Socks
    • 1098/1099/1050 - Pentesting Java RMI - RMI-IIOP
    • 1433 - Pentesting MSSQL - Microsoft SQL Server
    • 1521,1522-1529 - Pentesting Oracle TNS Listener
      • Oracle Pentesting requirements installation
      • TNS Poison
      • Remote stealth pass brute force
      • Oracle RCE & more
    • 1723 - Pentesting PPTP
    • 1883 - Pentesting MQTT (Mosquitto)
    • 2049 - Pentesting NFS Service
    • 2301,2381 - Pentesting Compaq/HP Insight Manager
    • 2375, 2376 Pentesting Docker
    • 3128 - Pentesting Squid
    • 3260 - Pentesting ISCSI
    • 3299 - Pentesting SAPRouter
    • 3306 - Pentesting Mysql
    • 3389 - Pentesting RDP
    • 3632 - Pentesting distcc
    • 3690 - Pentesting Subversion (svn server)
    • 4369 - Pentesting Erlang Port Mapper Daemon (epmd)
    • 5000 - Pentesting Docker Registry
    • 5353/UDP Multicast DNS (mDNS)
    • 5432,5433 - Pentesting Postgresql
    • 5601 - Pentesting Kibana
    • 5671,5672 - Pentesting AMQP
    • 5800,5801,5900,5901 - Pentesting VNC
    • 5984,6984 - Pentesting CouchDB
    • 5985,5986 - Pentesting WinRM
    • 6000 - Pentesting X11
    • 6379 - Pentesting Redis
    • 8009 - Pentesting Apache JServ Protocol (AJP)
    • 8089 - Splunkd
    • 9000 - Pentesting FastCGI
    • 9001 - Pentesting HSQLDB
    • 9042/9160 - Pentesting Cassandra
    • 9100 - Pentesting Raw Printing (JetDirect, AppSocket, PDL-datastream)
    • 9200 - Pentesting Elasticsearch
    • 10000 - Pentesting Network Data Management Protocol (ndmp)
    • 11211 - Pentesting Memcache
    • 15672 - Pentesting RabbitMQ Management
    • 27017,27018 - Pentesting MongoDB
    • 44818/UDP/TCP - Pentesting EthernetIP
    • 47808/udp - Pentesting BACNet
    • 50030,50060,50070,50075,50090 - Pentesting Hadoop
  • Pentesting Web
    • Web Vulnerabilities Methodology
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      • Web Vulns List
    • 2FA/OTP Bypass
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      • Java JSF ViewState (.faces) Deserialization
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    • Domain/Subdomain takeover
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  • CTF Write-ups
    • challenge-0521.intigriti.io
    • Try Hack Me
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      • Pickle Rick
  • 1911 - Pentesting fox
  • Online Platforms with API
  • Stealing Sensitive Information Disclosure from a Web
  • Post Exploitation
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On this page
  • Application Query Schemes Registration
  • Testing URL Handling and Validation
  • Testing URL Requests to Other Apps
  • Testing for Deprecated Methods
  • Calling arbitrary URLs
  • Fuzzing URL Schemes
  • Fuzzing Using Frida
  • References

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  1. Mobile Apps Pentesting
  2. iOS Pentesting

iOS Custom URI Handlers / Deeplinks / Custom Schemes

PreviousiOS BasicsNextiOS Hooking With Objection

Last updated 3 years ago

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Custom URL schemes . An app must declare support for the schemes and handle incoming URLs that use those schemes.

URL schemes offer a potential attack vector into your app, so make sure to validate all URL parameters and discard any malformed URLs. In addition, limit the available actions to those that do not risk the user’s data.

For example, the URI: myapp://hostname?data=123876123 will invoke the application mydata (the one that has register the scheme mydata) to the action related to the hostname hostname sending the parameter data with value 123876123

One vulnerable example is the following , discovered in 2010: The Skype app registered the skype:// protocol handler, which allowed other apps to trigger calls to other Skype users and phone numbers. Unfortunately, Skype didn't ask users for permission before placing the calls, so any app could call arbitrary numbers without the user's knowledge. Attackers exploited this vulnerability by putting an invisible <iframe src="skype://xxx?call"></iframe> (where xxx was replaced by a premium number), so any Skype user who inadvertently visited a malicious website called the premium number.

You can find the schemes registered by an application in the app's Info.plist file searching for CFBundleURLTypes (example from ):

<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleURLName</key>
        <string>com.iGoat.myCompany</string>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>iGoat</string>
        </array>
    </dict>
</array>

However, note that malicious applications can re-register URIs already registered by applications. So, if you are sending sensitive information via URIs (myapp://hostname?password=123456) a malicious application can intercept the URI with the sensitive information.

Also, the input of these URIs should be checked and sanitised, as it can be coming from malicious origins trying to exploit SQLInjections, XSS, CSRF, Path Traversals, or other possible vulnerabilities.

Application Query Schemes Registration

<key>LSApplicationQueriesSchemes</key>
    <array>
        <string>url_scheme1</string>
        <string>url_scheme2</string>
    </array>

canOpenURL will always return NO for undeclared schemes, whether or not an appropriate app is installed. However, this restriction only applies to canOpenURL.

Testing URL Handling and Validation

In order to determine how a URL path is built and validated, if you have the original source code, you can search for the following methods:

  • application:didFinishLaunchingWithOptions: method or application:will-FinishLaunchingWithOptions:: verify how the decision is made and how the information about the URL is retrieved.

func application(_ application: UIApplication, open url: URL, sourceApplication: String?) -> Bool {
    self.openUrl(url: url)
    return true
}

func application(_ application: UIApplication, open url: URL, sourceApplication: String?,
annotation: Any) -> Bool {
    self.openUrl(url: url)
    return true
}

func application(_ app: UIApplication, open url: URL,
options: [UIApplicationOpenURLOptionsKey : Any] = [:]) -> Bool {
    self.openUrl(url: url)
    return true
}

func application(_ application: UIApplication, handleOpen url: URL) -> Bool {
    self.openUrl(url: url)
    return true
}

Testing URL Requests to Other Apps

egrep -nr "open.*options.*completionHandler" ./Telegram-iOS/
egrep -nr "openURL\(" ./Telegram-iOS/
egrep -nr "mt-encrypted-file://" ./Telegram-iOS/
egrep -nr "://" ./Telegram-iOS/

Testing for Deprecated Methods

Search for deprecated methods like:

For example, here we find those three:

$ rabin2 -zzq Telegram\ X.app/Telegram\ X | grep -i "openurl"

0x1000d9e90 31 30 UIApplicationOpenURLOptionsKey
0x1000dee3f 50 49 application:openURL:sourceApplication:annotation:
0x1000dee71 29 28 application:openURL:options:
0x1000dee8e 27 26 application:handleOpenURL:
0x1000df2c9 9 8 openURL:
0x1000df766 12 11 canOpenURL:
0x1000df772 35 34 openURL:options:completionHandler:
...

Calling arbitrary URLs

  • Safari: To quickly test one URL scheme you can open the URLs on Safari and observe how the app behaves. For example, if you write tel://123456789 safari will try to start calling the number.

  • Notes App: Long press the links you've written in order to test custom URL schemes. Remember to exit the editing mode in order to be able to open them. Note that you can click or long press links including custom URL schemes only if the app is installed, if not they won't be highlighted as clickable links.

    • Go to the URL Handlers section. In URL schemes, click Refresh, and on the left you'll find a list of all custom schemes defined in the app being tested. You can load these schemes by clicking Open, on the right side. By simply opening a blank URI scheme (e.g., opening myURLscheme://), you can discover hidden functionality (e.g., a debug window) and bypass local authentication.

  • Frida:

    If you simply want to open the URL scheme you can do it using Frida:

    $ frida -U iGoat-Swift
    
    [iPhone::iGoat-Swift]-> function openURL(url) {
                                var UIApplication = ObjC.classes.UIApplication.sharedApplication();
                                var toOpen = ObjC.classes.NSURL.URLWithString_(url);
                                return UIApplication.openURL_(toOpen);
                            }
    [iPhone::iGoat-Swift]-> openURL("tel://234234234")
    true
    function openURL(url) {
        var w = ObjC.classes.LSApplicationWorkspace.defaultWorkspace();
        var toOpen = ObjC.classes.NSURL.URLWithString_(url);
        return w.openSensitiveURL_withOptions_(toOpen, null);
    }

    Note that the use of non-public APIs is not permitted on the App Store, that's why we don't even test these but we are allowed to use them for our dynamic analysis.

Fuzzing URL Schemes

If the app parses parts of the URL, you can also perform input fuzzing to detect memory corruption bugs.

  • Generate payloads.

  • For each of them call openURL.

  • Check if the app generates a crash report (.ips) in /private/var/mobile/Library/Logs/CrashReporter.

Fuzzing Using Frida

Before running the fuzzer we need the URL schemes as inputs. From the static analysis we know that the iGoat-Swift app supports the following URL scheme and parameters: iGoat://?contactNumber={0}&message={0}.

$ frida -U SpringBoard -l ios-url-scheme-fuzzing.js
[iPhone::SpringBoard]-> fuzz("iGoat", "iGoat://?contactNumber={0}&message={0}")
Watching for crashes from iGoat...
No logs were moved.
Opened URL: iGoat://?contactNumber=0&message=0

References

Apps can call to verify that the target app is available. However, as this method was being used by malicious app as a way to enumerate installed apps, by adding the LSApplicationQueriesSchemes key to the app's Info.plist file and an array of up to 50 URL schemes.

: verify how the resource is being opened, i.e. how the data is being parsed, verify the , especially if access by the calling app () should be allowed or denied. The app might also need user permission when using the custom URL scheme.

In Telegram you will :

The method and the are responsible for opening URLs (i.e. to send requests / make queries to other apps) that may be local to the current app or it may be one that must be provided by a different app. If you have the original source code you can search directly for usages of those methods.

Additionally, if you are interested into knowing if the app is querying specific services or apps, and if the app is well-known, you can also search for common URL schemes online and include them in your greps (l).

:

Start IDB, connect to your device and select the target app. You can find details in the .

In this example from the author uses the non-public API LSApplicationWorkspace.openSensitiveURL:withOptions: to open the URLs (from the SpringBoard app):

What we have learned above can be now used to build your own fuzzer on the language of your choice, e.g. in Python and call the openURL using . That fuzzer should do the following:

The project offers fuzzing dictionaries that you can use as payloads.

Doing this with Frida is pretty easy, you can refer to this to see an example that fuzzes the iGoat-Swift app (working on iOS 11.1.2).

allow apps to communicate via a custom protocol
bug in the Skype Mobile app
iGoat-Swift
canOpenURL:
from iOS 9.0 the URL schemes passed to it must be also declared
application:openURL:options:
options
sourceApplication
find four different methods being used
openURL:options:completionHandler:
deprecated openURL: method of UIApplication
ist of iOS app schemes
application:handleOpenURL:
openURL:
application:openURL:sourceApplication:annotation:
IDB
IDB documentation
Frida CodeShare
Frida's RPC
FuzzDB
blog post
LogoiOS Platform APIsMobile Security Testing Guide