iOS malware: myth or reality?

talk given at Security B-Sides London

Transcript

1. C O N F I D E N T I A L ©2016 KUDELSKI GROUP / All rights reserved. iOS MALWARE : MYTH OR REALITY? Julien Bachmann @milkmix_
2. INTRODUCTION
3. C O N F I D E N T I A L 3 ©2016 KUDELSKI GROUP / All rights reserved. 2010 2011 2012 2013 2014 2015 SOME HISTORY ON BANKING MALWARE Zeus SpyEye Carberp HesperBot Android.iBanking Android.BankBot Android.bankosy
4. C O N F I D E N T I A L 4 ©2016 KUDELSKI GROUP / All rights reserved. ONLY AN ANDROID PROBLEM RIGHT? Two facts to consider iOS malware is a real thing, even if less widespread now If you are using iOS in your enterprise you might be at risk src: Verizon DBIR 2015
5. C O N F I D E N T I A L 5 ©2016 KUDELSKI GROUP / All rights reserved. 2009 2012 2014 2015 2016 SOME HISTORY ON iOS MALWARE iKee (ssh) Find and Call AdThief Unflod WireLurker XcodeGhost YiSpecter Muda ZergHelper AceDeceiver
6. QUICK RECAP ON iOS SECURITY
7. C O N F I D E N T I A L 7 ©2016 KUDELSKI GROUP / All rights reserved. APPLICATIONS INSTALLATION Limited number of installation paths Closed platform well restricted by Apple Only authorized methods controlled by Apple on non- jailbroken device
8. C O N F I D E N T I A L 8 ©2016 KUDELSKI GROUP / All rights reserved. APPLICATIONS INSTALLATION AppStore AdHoc / self signed In House 3rd party stores (jailbreak)
9. C O N F I D E N T I A L 9 ©2016 KUDELSKI GROUP / All rights reserved. APPLICATIONS INSTALLATION AppStore Require Developer certificate Applications are reviewed In House Common method for enterprise applications Require Enterprise Developer account Require Provisioning profile installed on device Ad Hoc Used during development Limited to 100 devices with provisioned UDID Self signed New with iOS 9 and Xcode 7, sign for personal devices
10. C O N F I D E N T I A L 10 ©2016 KUDELSKI GROUP / All rights reserved. APPLICATIONS INSTALLATION The jailbroken case Several advantages while jailbreaking a device Allows to validate security of applications But disable code signing validations Allows installing applications from untrusted sources
11. C O N F I D E N T I A L 11 ©2016 KUDELSKI GROUP / All rights reserved. APPLICATIONS RESTRICTIONS Limitations put in place by Apple Applications running in a sandbox Seat-Belt Limited access to filesystem and resources Applications are isolated from one another Requested accesses validated on the AppStore Some limitations may apply…
12. C O N F I D E N T I A L 12 ©2016 KUDELSKI GROUP / All rights reserved. HOW DEVICES ARE INFECTED? Mostly phishing Lure users into installing malicious application Download link in emails / messages Used it before in phishing campaign for customer : ~10% No exploits and watering hole? Exploitation of software vulnerabilities through the browser Possible but remote code execs are expensive on iOS
13. C O N F I D E N T I A L 13 ©2016 KUDELSKI GROUP / All rights reserved. HOW DEVICES ARE INFECTED?
14. C O N F I D E N T I A L 14 ©2016 KUDELSKI GROUP / All rights reserved. HOW DEVICES ARE INFECTED? Traffic injection From the public news, most cases currently in Asia DNS redirects in China Attacks on mobile devices through fake eNodeB Physical attacks Through MobileDevice framework on USB/WiFi AirDrop software flaws Code injection Ex. JSPatch
15. C O N F I D E N T I A L 15 ©2016 KUDELSKI GROUP / All rights reserved. HOW DEVICES ARE INFECTED? Physical attacks Through MobileDevice framework on USB/WiFi
16. C O N F I D E N T I A L 16 ©2016 KUDELSKI GROUP / All rights reserved. CODE SIGNING? Phishing is not enough Code signing still performed by iOS Except on jailbroken devices Ad Hoc Too complicated, requires UDID Leaks in the past years, limited now with Apple restrictions Potentially on very targeted attacks Enterprise Developer Certificate User validation Certificate can be easily revoked by Apple upon detection
17. C O N F I D E N T I A L 17 ©2016 KUDELSKI GROUP / All rights reserved. CODE SIGNING? Enterprise Developer Certificate
18. C O N F I D E N T I A L 18 ©2016 KUDELSKI GROUP / All rights reserved. CODE SIGNING? Recently in the news “Malware bypassing Apple code signing mechanism” AceDeceiver Truth (explanation w/o the hype) Still requires to be published and accepted by Apple at least once in one of the stores (US, CH, CN, …) Can use geolocation of incoming IP addresses to enable/disable features in the code Possible to exploit design flaw in the validation process when installing from iTunes on Mac/PC Allows to install the malware from Mac/PC even if certificate revoked
19. C O N F I D E N T I A L 19 ©2016 KUDELSKI GROUP / All rights reserved. CODE SIGNING? http://researchcenter.paloaltonetworks.com/2016/03/acedeceiver-first-ios-trojan-exploiting-apple-drm-design-flaws-to-infect-any-ios-device/
20. MALICIOUS ACTIONS
21. C O N F I D E N T I A L 21 ©2016 KUDELSKI GROUP / All rights reserved. APPSTORE PERMISSIONS Audio recording Easily performed through the API When in background applications are preempted by iOS Except if defined as background application Ribbon displayed to the user Keylogging Since iOS8 : extensions (keyboard, browser filtering, …) Isolated from standard application so no access to Internet or files… … except if requested
22. C O N F I D E N T I A L 22 ©2016 KUDELSKI GROUP / All rights reserved. KEYLOGGING FROM THE APPSTORE User’s validation
23. C O N F I D E N T I A L 23 ©2016 KUDELSKI GROUP / All rights reserved. PRIVATE API In the news
24. C O N F I D E N T I A L 24 ©2016 KUDELSKI GROUP / All rights reserved. SANDBOX IS LIMITING ACTIONS RIGHT? Entitlements 1. Developers should specify entitlements at compilation • http://newosxbook.com/ent.jl 2. Validated by the AppStore 3. Some additional rights for selected partners 4. Enforced on device by seat-belt Private API Forbidden by Apple in the guidelines Still requires entitlements to access data due to sandbox Does not break applications isolation principle Would require to elevate privileges to do so Or flaws in the private APIs validation mechanism (Stefan Esser app) Difficult to detect with automated analysis (static and dynamic)
25. C O N F I D E N T I A L 25 ©2016 KUDELSKI GROUP / All rights reserved. SANDBOX IS LIMITING ACTIONS RIGHT? Entitlements
26. C O N F I D E N T I A L 26 ©2016 KUDELSKI GROUP / All rights reserved. SANDBOX IS LIMITING ACTIONS RIGHT? Listing private APIs functions Nicolas Seriot online list Using classdump-dyld on a jailbroken device Calling private APIs Can be called directly Through dynamic loading dlopen / dlsym Using Objective-C reflection property
27. C O N F I D E N T I A L 27 ©2016 KUDELSKI GROUP / All rights reserved. SANDBOX IS LIMITING ACTIONS RIGHT? Listing private APIs functions
28. C O N F I D E N T I A L 28 ©2016 KUDELSKI GROUP / All rights reserved. SANDBOX IS LIMITING ACTIONS RIGHT? When linked Objective-C reflection
29. C O N F I D E N T I A L 29 ©2016 KUDELSKI GROUP / All rights reserved. THE IN HOUSE CASE Entitlements Defined at compilation Not validated by Apple outside of the AppStore flow As seen allows to use more sensitive Private API functions Offers more possibilities CoreTelephony framework Notifications on calls or messages IMSI / IMEI retrieval Install applications Access private information …
30. NON-APPLICATION BASED ATTACKS
31. C O N F I D E N T I A L 31 ©2016 KUDELSKI GROUP / All rights reserved. CONFIGURATION PROFILES Probably used in your organization Configure email client Device certificate Corporate WiFi credentials … Also used by attackers Define proxy and install CA for SSL interception Required to run Enterprise Developer signed applications
32. PROTECTION AND DETECTION
33. C O N F I D E N T I A L 33 ©2016 KUDELSKI GROUP / All rights reserved. DETECTION Mobile devices are more complex to protect Network side Not always using your egress point Web filtering / network monitoring not applicable Endpoint side Operating system less open to 3rd party drivers Applications isolation Not an AV friendly environment
34. C O N F I D E N T I A L 34 ©2016 KUDELSKI GROUP / All rights reserved. DETECTION ON THE NETWORK IDS like features Use rulesets specific to mobile malware Examples Emerging Threats MOBILE_MALWARE rules Lookout Mobile Threat Intelligence feed Android only AFAIK Detect access to non-corporate configuration Detect download of IPA files signed with external Enterprise Developer accounts
35. C O N F I D E N T I A L 35 ©2016 KUDELSKI GROUP / All rights reserved. DETECTION ON THE DEVICES Leverage existing MDM/MAM solution Retrieve installed provisioning profiles All external ones should be suspicious Retrieve installed applications bundle names Match known malicious
36. C O N F I D E N T I A L 36 ©2016 KUDELSKI GROUP / All rights reserved. DETECTION ON THE DEVICES Command line tools ideviceinstaller ideviceprovision
37. C O N F I D E N T I A L 37 ©2016 KUDELSKI GROUP / All rights reserved. DETECTION ON THE DEVICES Forensics from logs installd SpringBoard
38. C O N F I D E N T I A L 38 ©2016 KUDELSKI GROUP / All rights reserved. DETECTION ON THE DEVICES Forensics from side channels logs Battery usage Data usage Both contain applications name and last executed timestamp Available from backups
39. C O N F I D E N T I A L 39 ©2016 KUDELSKI GROUP / All rights reserved. DETECTION ON THE DEVICES One remark on forensics acquisition Enterprise app binaries were never part of the backups Since iOS 9 it is the same for AppStore ones Still, those are encrypted so not really useful
40. C O N F I D E N T I A L 40 ©2016 KUDELSKI GROUP / All rights reserved. DETECTION ON THE DEVICES Future? USB scanning terminal to match known malicious bundles Workstation AV scanning connected devices
41. C O N F I D E N T I A L 41 ©2016 KUDELSKI GROUP / All rights reserved. PROTECTION Update devices Decrease potential vulnerabilities exploitation Prevent known jailbreaking methods Device hardening iOS security best-practices Disable AirDrop Force 6-digits passcode …
42. C O N F I D E N T I A L 42 ©2016 KUDELSKI GROUP / All rights reserved. PROTECTION Users training Do not install 3rd party provisioning profiles Do not install applications outside of the AppStore or provided by corporate MDM
43. C O N F I D E N T I A L 43 ©2016 KUDELSKI GROUP / All rights reserved. FOR THOSE READING FRENCH
44. C O N F I D E N T I A L 44 ©2016 KUDELSKI GROUP / All rights reserved. ACKNOWLEDGEMENTS Claud Xiao from Palo Alto for sharing his samples with the research community
45. C O N F I D E N T I A L 45 ©2016 KUDELSKI GROUP / All rights reserved.