Thread by @duniel_pls

Hey kids! Wanna research some shitty Atrient Android apps? Follow along with me, this is going to be fun. (1/?)

So it turns out Atrient has been creating and releasing shitty Android apps in their customers' names. After having a closer look, I realized that Atrient packaged their clients' private RSA keys into the aforementioned apps, most likely used for backend communications. (2/?)

First you find Atrient's client list (tip: it's on their website at atrient.com/about/client-l…) and look up Android apps released in their name. Download them using the tool `gplaycli', or pull the APKs off some sketchy-looking site online. (3/?)

Once you've downloaded the APK (`gplaycli -d name-of-app'), you do two things: First run `d2j-dex2jar com.vendor.package.apk' to convert Android .dex to Java .class. Then you extract the app using `apktool d com.vendor.package.apk'. (4/?)

`apktool' will create the `com.vendor.package' directory in your current directory. When you've done this, open the `com.vendor.package-dex2jar.jar' file d2j generated in the `jd-gui' program - it's a Java decompiler. (5/?)

With `jd-gui' purring nicely, hit Ctrl+Shift+S, check all the "Search For" boxes, and search for "PKCS12". It *should* come up with `NetworkManager.class', double click it and it'll take you to the matching code. (6/?)

You should either find the password in cleartext in a string nearby, or something like `paramContext.getString(2131492865);`. If you come across the number, open `R.class', Ctrl+F for it, and copy the variable identifier. (7/?)

Then look for it in the apktool directory, in `com.vendor.package/res/values/strings.xml' - the password should be there, in plaintext. (8/?)

Anyway, once you have the password, move to `com.vendor.package/assets', find the `.p12' files, and run `keytool -list -v -keystore <KEYSTORE_FILE> -storetype PKCS12 -storepass "<PASSWORD_HERE>"'. It'll spit out a bunch of data, including an encrypted RSA key at the top. (9/?)

Copy that key (with the header and footer) to a separate file, name it something like "thedomain.tld.key.enc", and run `openssl rsa -in domain.tld.key.enc -out domain.tld.key'. The password should be the same, and you'll have the decrypted key. (10/11)

Once you have the RSA private key, you could do something funky, like MitM-attacks or impersonating the server. Or whatever your heart desires! I suspect these keys are used for backend communications, as the crypto. fingerprints differ from the ones on the websites. (11/11)

POST SCRIPTUM: These apps were publicly released by Atrient, and with them, the casinos' private RSA keys. The decryption passwords were also shockingly easy to find, and to make matters worse, it turns out most of the certificates are wildcard DV certs.

CORRECTION: You can combine the keytool and openssl command into one: `openssl pkcs12 -in keystorefile.p12 -nodes -nocerts -out privatekey.pem'

Update: I archived all the Atrient applications, the originals as published on Google Play: duniel.no/atrient_apps/

Another update: I can confirm that the keys are used for backend comms.