![]() Anyway, it’s your decision to put yourself through this or not, so the next time you want to be a YouTube star, you’ll do it your way and not accidentally by SpyPhone. The next day you might find yourself on YouTube with 8 million views. Just so you know, in this particular case, this nice app would most probably record your voice when you’re rocking the Jingle Bells in wild style, thinking nobody hears you. Why? Well, it’s an app that’s supposed to play Christmas carols and not “SpyMyPhone” or whatever that PUP warning says. What should you do? Well, what I would do is to sing Silent Night to that app and wave goodbye while uninstalling it. The detection name reads “ Android:SpyPhone-E ”. Let’s say you downloaded an app that’s called “ Christmas Carols” (don’t panic about that, either it’s still a month and a half till Christmas) and a PUP warning hits you. PUP detections were made to warn people when a suspicious component or ability is detected within the application. It’s not a standard virus and, no, your life is not in danger. When a PUP alert attacks you, don’t panic.įor starters, it’s just a warning. You probably already had a chance to meet some PUPs on a Windows PC, but how does a PUP look on an Android phone? How will you know how to handle it? All of this will be explained here. Potentially Unwanted Program – that’s what PUP stands for. A reverse engineer can disassemble the sample with baksmali, insert calls to Android logging functions (see below), recompile the application (smali), and run it.Android PUP Detections - Oh, Not That One Again! However, this tool only works with samples that use old versions of DexGuard, not the more recent ones. The script decrypts encrypted strings, which makes reversing easier. provides a script template that can be applied to each DexGuard-ed sample. Second, its reversing can be made easier by using the following tools or techniques:ĭexGuard decryption python script. type f -name “*.smali” -print | perl -ne ‘print if /]/’ The code snippet below lists non-ASCII smali files in smali disassembled code. identifying the use of DexGuard on a sample – is usually fairly visual: the repetitive use of non ASCII characters gives it away. Meanwhile, we provide a code snippet that can be used to detect it, and three different ways to help with the reversing of DexGuard-ed samples.įirst, its detection – i.e. It is as if reverse engineers have had their senses dulled: text strings and even some familiar function calls and patterns no longer exist to guide the analyst to the more interesting parts of the code.įortunately, no obfuscator is perfect. Tools such as JD-GUI and Androguard are more difficult to use (e.g. The main reason why DexGuard-obfuscated samples are more difficult to work with is because the class and method names are replaced with non-ASCII characters and strings are encrypted. Working on DexGuard-ed samples is much more difficult. We provide the current state of play as regards ongoing research to detect and mitigate against these mechanisms. There are techniques for injecting malicious bytecode, manipulating the DEX file format to hide methods, and customizing the output of encryption to hide an APK. Finally, we reveal a few new obfuscation techniques of which we are aware, which might be used by malware authors in the future. We provide examples and supply the sha256 hash in each case. We also list some custom obfuscation techniques we have encountered in malware: loading native libraries, hiding exploits in package assets, truncating URLs, using encryption etc. We present five off-the-shelf products ( ProGuard, DexGuard, APK Protect, HoseDex2Jar and Bangcle) and make suggestions as to how researchers can detect when they have been used in malware, and some techniques to help with their reversing. ![]() This paper focuses on obfuscation techniques encountered while analysing Android malware. Malware authors are certainly creative when it comes to hiding their payloads from analysts’ eyes, using methods such as emulator detection, application icon hiding, reflection etc.
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