Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
[mDevCamp 2020] Reversing Android Apps
Search
Marc Obrador
June 11, 2020
Programming
3
2.7k
[mDevCamp 2020] Reversing Android Apps
Marc Obrador
June 11, 2020
Tweet
Share
More Decks by Marc Obrador
See All by Marc Obrador
[Droidcon London 2023] REST in Peace: A Journey Through API Protection
marcobrador
0
88
[Droidcon Berlin 2023] Obfuscation in Mobile Apps
marcobrador
0
1.2k
[WeAreDevelopers World Conference] Reversing Android Apps
marcobrador
0
590
Introduction to Mobile App Security
marcobrador
2
370
[ICE71 CyberSecurity Networking Night] Mobile App Security: A developer's introduction
marcobrador
0
770
[GDG BCN 2019] Introduction to Android App Security
marcobrador
1
870
[DroidCon Lisbon 2019] Intro to Android App Security
marcobrador
2
440
Other Decks in Programming
See All in Programming
みんなでプロポーザルを書いてみた
yuriko1211
0
260
cmp.Or に感動した
otakakot
2
150
どうして僕の作ったクラスが手続き型と言われなきゃいけないんですか
akikogoto
1
120
受け取る人から提供する人になるということ
little_rubyist
0
230
3 Effective Rules for Using Signals in Angular
manfredsteyer
PRO
1
100
EventSourcingの理想と現実
wenas
6
2.3k
watsonx.ai Dojo #4 生成AIを使ったアプリ開発、応用編
oniak3ibm
PRO
1
100
subpath importsで始めるモック生活
10tera
0
300
Webの技術スタックで マルチプラットフォームアプリ開発を可能にするElixirDesktopの紹介
thehaigo
2
1k
.NET のための通信フレームワーク MagicOnion 入門 / Introduction to MagicOnion
mayuki
1
1.5k
距離関数を極める! / SESSIONS 2024
gam0022
0
280
Arm移行タイムアタック
qnighy
0
320
Featured
See All Featured
Distributed Sagas: A Protocol for Coordinating Microservices
caitiem20
329
21k
Site-Speed That Sticks
csswizardry
0
23
Adopting Sorbet at Scale
ufuk
73
9.1k
Typedesign – Prime Four
hannesfritz
40
2.4k
Building Better People: How to give real-time feedback that sticks.
wjessup
364
19k
A designer walks into a library…
pauljervisheath
203
24k
How STYLIGHT went responsive
nonsquared
95
5.2k
Into the Great Unknown - MozCon
thekraken
32
1.5k
Faster Mobile Websites
deanohume
305
30k
Design and Strategy: How to Deal with People Who Don’t "Get" Design
morganepeng
126
18k
GitHub's CSS Performance
jonrohan
1030
460k
Building Adaptive Systems
keathley
38
2.3k
Transcript
Reversing Android Apps
Marc Obrador Lead Architect @ Build38 Barcelona
[email protected]
@marcobrador /in/marc-obrador
None
Source: https://en.wikipedia.org/wiki/Reverse_engineering It’s illegal (in the EU)!
None
Josep Bernad iOS Albert Sunyer UI
Artà is in Mallorca ABF takes place (usually) in June
COVID-19 pushed it to … ?
None
Get to know the app Step 0
Get to know the app
Get to know the app
Get to know the app
Get to know the app
Static Analysis Step 1
Static Analysis
Getting the APK
Decompiling the app https://ibotpeaches.github.io/Apktool/ $ brew install apktool
Decompiling the app
None
None
None
None
None
Let’s keep looking around
Wait… “discount codes”?
App users get a discount for events
None
Let’s take a closer look…
None
HTTP Basic Authorisation = Base64(“username:password”)
None
HTTP Basic Authorisation = Base64(“username:password”) username = “string1” xor “string2”
pasword = “string3” xor “string2”
None
Protecting against static analysis ProGuard is a good start… for
regular apps • It’s just method renaming and code shrinking • Tools for reversing ProGuard exist: http://apk-deguard.com/ Other (paid) alternatives exist for obfuscation Writing sensitve code in native (NDK) is a good idea
Dynamic Analysis Step 2
Dynamic Analysis
Dynamic Analysis
Network Sniffing a.k.a MITM
Network Sniffing https://www.charlesproxy.com/
Setting Up Charles Proxy
Setting Up Charles Proxy
Setting Up Charles Proxy
First attempt…
First attempt…
Setting Up Charles Proxy
Setting Up Charles Proxy
Let’s try again…
None
None
None
None
None
• Implement Root/Debugger/Emulator/Hooking Framework detection • Use certificate pinning •
Try to detect app tampering Protecting against dynamic analysis
Using Certificate Pinning Source: https://developer.android.com/training/articles/security-config
Tampering with the App Step 3
Assuming the app implemented Certificate Pinning…
$ adb install “Downloads/Artà Beer Festival_v1.2.5_apkpure.com.apk” Performing Streamed Install Success
$ adb shell am start com.marcobrador.android.artabeerfestival/.SplashActivity Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category .LAUNCHER] cmp=com.marcobrador.android.artabeerfestival/.SplashActivity }
Let’s try to remove it
None
None
None
Time to give it a try!
None
None
Preventing Repackaging
Looks like we are done here Looks like we are
done here
This code can be removed, too!
Closing Thoughts
None
None
None
Thank you!