// CTF CHALLENGE 27

Reverse Engineering: Patching

Analyze the following disassembled code block (Smali) belonging to a Malware's Root check function.

.method private checkRoot()Z
    .locals 2
    invoke-static {}, Lcom/malware/Utils;->isRooted()Z
    move-result v0
    
    # [!] LÓGICA DE CONTROL DE FLUJO
    if-eqz v0, :cond_0
    
    # Ejecuta el Malware si pasa la comprobación
    invoke-virtual {p0}, Lcom/malware/Main;->startPayload()V
    
    :cond_0
    # Cierra la aplicación (Anti-Análisis)
    invoke-static {v1}, Ljava/lang/System;->exit(I)V
    return-void
.end method            

1. What command-line tool did you use to extract this Smali code and recompile it later?

2. Look at the line if-eqz v0, :cond_0. What exact instruction would you replace it with to invert the logic and trick the app?

3. Before touching Smali, you probably read the Java code comfortably. Name a tool capable of decompiling an APK to readable Java code.

Reverse Engineering: Patching

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