看雪题库_Reverse_马到成功

roger

Pragyan CTF 2015: Fast and Furious

Category: Android
Points: 100
Solves 69
Description:

fast.apk

Write-up

by polym

After decompiling the fast.apk application file, we detect a hardcoded string, 65544231587a52794d3138316458417a636c396d4e44553343673d3d, in Main.java.

Converting this Hex string to an ASCII string, we get eTB1XzRyM181dXAzcl9mNDU3Cg=, which is a base64 encoded string.

Base64 Decoding this string results in the flag:

$ base64 --decode <<< 'eTB1XzRyM181dXAzcl9mNDU3Cg='
y0u_4r3_5up3r_f457

The flag is y0u_4r3_5up3r_f457.

Other write-ups and resources

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

# 注册
public static String a(String paramString) {
        StringBuilder stringBuilder = new StringBuilder();
        for (byte b = 0; b < paramString.length(); b += 2)
            stringBuilder.append((char)Integer.parseInt(paramString.substring(b, b + 2), 16));
        return stringBuilder.toString();
    }

    public static void main(String[] args) {
        System.out.println("Hello JAVA");
        String str = a("65544231587a52794d3138316458417a636c396d4e44553343673d3d");
        System.out.println(str);
    }
返回值是：
eTB1XzRyM181dXAzcl9mNDU3Cg==
解密这串base64就是了