Security Issues In Android (Custom ROM’s) Anant Shrivastava http://anantshri.info
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Agenda ● Introduction to Concept : Custom Rom ● Why Security Review ● Security Issues ● PoC : Data Theft Tool ● Protection Tips ● Demo : Tool
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What is Android ROM ● Android ROM is the OS Firmware layer of Phone. ● Generally consist of /system partition ● May include /data partition ● Contains – Kernel – Dalvik – Libraries – Framework – Application (Vendor Provided)
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Android Architecture
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ROM’s concept ● Android Basically has two ROM’s or firmwares. ● Stock : Pre installed by Manufacturers ● ● Custom : AfterMarket version, not supported by manufacturer. Example – CyanogenMod : claimed as aftermarket firmware. – MIUI : Chinese by origin, mimic’s iPhone Looks. – OMFGB : Gingerbread Enhanced
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Advantage of Custom ROM’s ● Bring out the best of all World’s, example : – You may like SE hardware but love htc sense UI. – You prefer minimal phone, or avoid default apps. – Roms with specific features ● When Carrier / manufacturer stop providing updates ● Bleeding Edge (2.3.7) ● Pre-rooted ● Targetted : Speed, Gaming,Performance, Battery ● Overclocking and underclocking
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Where can i get it • http://cyanogenmod.com • http://miui.org • http://forum.xda-developers.com • http://android.modaco.com • http://modmymobile.com/forum.php • And many more underground forums.
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Recipe Modify Stock ROM ● Parellel after market ROM’s ● Best of Both ● General ROM cookers are here for either ● ● Fun ● Profit ● They Can attitude.
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Why Security Review Next In Thing : Designing Malware and Exploits for android On top of that : employee’s Pressure to integrate Android in Corporate infrastructure. AfterMarket Distribution like CyanogenMod are considered viable alternative. Lots of work is underway to safely implement CyanogenMod in Corporate Environment.
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Are we Missing Something ● Did anyone tried peeking under the hood. ● This is what we will be doing today
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Practices under Scrutiny ● USB Debugging enabled ● Adb Shell root mode ● System permissions ● Installation from unknown source ● Adb shell over wifi ● Su acccess and settings ● Custom Recoveries
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USB Debugging enabled ● ADB or Android Debug Bridge ,Google’s Debug. ● Menu → Settings → Applications → Development ● Supports – Push / Pull Files and folders – Remount system partitions – Installation of software without prompt – Fastboot with different Kernel
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Adb Shell root mode ● Special Setting making adb run in root mode. ● Activated at boot time. ● boot.img → ramdisk.cpio.gz → build.prop ● Do you pay attention to the other end of charging Dock. :)
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ADB Shell over WiFi ● This Settings allow adb shell to be used over wifi network. (Freedom from Wires :) ) ● At boot time or run time both. ● service.adb.tcp.port = <tcp_port_no> ● Combine with our beloved ro.secure, you literally handover your device shouting : ”PLEASE OWN ME”. ● This is hypothetical as of now, no known usage found so far.
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System permissions ● ● ● ● /system should be readonly as its critical section of phone. Its observed at lots of places where Cooker’s keep 777 settings for /system Do you remember : – /system/app : system apps – /system/bin : executable Remember ROOTKITS, TROJAN, MALWARE
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Unknown Source Installation ● ● This Settings disallows third party softwares, forces the use of Android Market. Aftermarket forum practices, enable Unknown Sources.
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Su Access ● ● ● ● With greater Power comes greater responsibility. SU or switch user binary is a direct indication of a rooted device. However default protection from unauthorized execution is not available. Superuser.apk is only known protection.
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Recovery Images ● ● ● Android Provides an option to install Custom Recovery softwares. Recovery softwares provide un restricted root access by default. Putting a phone in recovery mode is as simple as reboot, press backspace or vol_down till recovery starts.
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Demo PoC tool DEMO IS INTENTIONALLY NOT DEVELOPED TO A LARGE EXTEND TO AVOID SCRIPT KIDDIE APPROACH
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Protection ● Developers – Avoid settings not so required for normal user. – Give recomendation to close unknow source setting. – ● Users – Take a closer look at Development Process. – Ask Questions – Run ARE YOU INSECURE
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Are you Insecure Demo
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About Me Anant Shrivastava CEH, RHCE Interested in Android, Linux, Web 2.0 Member of Null and G4H ● Email : anant@anantshri.info ● Web : http://anantshri.info ● Blog : http://blog.anantshri.info
