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roger

Pragyan CTF 2015: Hackerz

Category: Android
Points: 100
Solves 75
Description:

Adam and Eve where in the Garden of Eden. Snake offered apple to Eve and that was the first SYN.

circle.apk

Write-up

by polym

When decompiling the circle.apk application file with jadx, we see four Java files:

$ jadx -x circle.apk
INFO  - output directory: circle
INFO  - loading ...
WARN  - Indent < 0
INFO  - processing ...
INFO  - done
$ tree
.
├── AndroidManifest.xml
└── com
    └── pragyan
        └── circle
            ├── Main.java
            ├── a.java
            ├── b.java
            └── c.java

3 directories, 5 files

In b.java, we see a base64 encoded string, eTB1XzRyM180X2g0Y2szcg==.

By base64 decoding this string, we get the flag:

$ base64 --decode <<< 'eTB1XzRyM180X2g0Y2szcg=='
y0u_4r3_4_h4ck3r

The flag is y0u_4r3_4_h4ck3r.

Other write-ups and resources

• https://ctf-team.vulnhub.com/pragyan-ctf-2015-android/