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[原创] 看雪CTF.TSRC 2018 团队赛 第五题 交响曲
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2018-12-9 18:07 2227
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拿到一个apk,拖到jadx里面,拿到源码。
package cn.kwaiching.crackme; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; public class CrackMe extends AppCompatActivity { int[] a = new int[]{16, 6, 7, 10, 9, 16, 10, 8, 8, 9, 6, 6}; int[] b = new int[]{5, 10, 8, 15, 16, 15, 8, 16, 8, 16, 9, 17, 8, 17, 10, 8, 9, 18, 5, 15, 10, 9, 8, 9, 15, 18, 7, 8, 16, 6}; int[] c = new int[]{6, 7, 18, 9, 5, 16, 9, 15, 18, 8, 9, 5}; int[] d = new int[]{7, 7, 9, 12, 8, 7, 13, 5, 14, 5, 9, 17, 5, 7, 12, 8, 8, 6, 19, 6, 8, 16, 10, 6, 12, 9, 6, 7, 12, 5, 9, 8, 7, 8, 15, 9, 16, 8, 8, 19, 12, 6, 8, 7, 5, 15, 6, 16, 15, 7, 9, 12, 10, 7, 15, 6, 5, 14, 14, 9}; int e; int f; int g; int h; int i; int j; int k; String[] l = new String[73]; String[] m = new String[]{"23to01", "01to03", "03to05", "05to07", "07to09", "09to11", "11to13", "13to15", "15to17", "17to19", "19to21", "21to23"}; TextView n; protected void onCreate(Bundle bundle) { super.onCreate(bundle); setContentView((int) R.layout.activity_fate_me); b(); this.n = (TextView) findViewById(R.id.fate); ((Button) findViewById(R.id.ok)).setOnClickListener(new OnClickListener() { public void onClick(View view) { try { CrackMe.this.a(); } catch (Exception unused) { CrackMe.this.n.setText(CrackMe.this.getString(R.string.notMe)); } } }); } private void a() { try { c(); if (this.j == 0 || this.i == 0 || this.h == 0) { this.n.setText(getString(R.string.notMe)); return; } d(); a(((e() + f()) + g()) + h()); } catch (Exception unused) { this.n.setText(getString(R.string.notMe)); } } private void b() { for (int i = 0; i <= 72; i++) { if (i != 34) { this.l[i] = getResources().getString(R.string.success00); } else { this.l[i] = getResources().getString(R.string.success34); } } } private void c() { try { String obj = ((EditText) findViewById(R.id.code)).getText().toString(); this.j = 0; this.i = 0; this.h = 0; this.j = Integer.parseInt(obj.length() > 4 ? obj.substring(0, 4) : obj); if (this.j > 0 && this.j < 189) { this.j = 0; } if (this.j <= 1983 || this.j >= 2007) { this.j = 0; } this.i = Integer.parseInt(obj.length() > 6 ? obj.substring(4, 6) : obj); if (this.i < 1 || this.i > 12) { this.i = 0; } if (obj.length() > 8) { obj = obj.substring(6, 8); } this.h = Integer.parseInt(obj); if (this.h < 1 || this.h > 31) { this.h = 0; } } catch (Exception unused) { this.n.setText(getString(R.string.notMe)); } } private void d() { try { if (this.j == 1989 || this.j == 2004) { this.h = 31; } if (this.i == 1 || this.i == 4 || this.i == 5 || this.i == 7 || this.i == 10 || this.i == 11 || this.i == 12) { this.j = 1999; } if (this.j <= 1994 && (this.i == 2 || this.i == 6 || this.i == 8)) { this.i = 3; } if (this.j >= 1996 && (this.i == 2 || this.i == 6 || this.i == 8)) { this.i = 9; } if (this.j == 1995 && (this.h > this.i + 2 || this.i == this.h)) { this.i = 6; } this.g = this.j; this.f = this.i; this.e = this.h; } catch (Exception unused) { this.n.setText(getString(R.string.notMe)); } } private void a(int i) { if (i > 34 || i < 34) { this.n.setText(getString(R.string.notMe)); return; } try { this.n.setText(String.format("%s%s", new Object[]{getString(R.string.me), this.l[i]})); ((Button) findViewById(R.id.ok)).setEnabled(false); } catch (Exception unused) { this.n.setText(getString(R.string.notMe)); } } private int e() { try { return this.d[(this.g - 1900) % 60]; } catch (Exception unused) { this.n.setText(getString(R.string.notMe)); return 0; } } private int f() { try { return this.c[this.f - 1]; } catch (Exception unused) { this.n.setText(getString(R.string.notMe)); return 0; } } private int g() { try { return this.b[this.e - 1]; } catch (Exception unused) { this.n.setText(getString(R.string.notMe)); return 0; } } /* JADX WARNING: Removed duplicated region for block: B:17:0x0050 A:{Catch:{ Exception -> 0x005c }} */ private int h() { /* r6 = this; r0 = 2131165227; // 0x7f07002b float:1.7944665E38 double:1.0529355243E-314; r1 = 2131427370; // 0x7f0b002a float:1.8476354E38 double:1.05306504E-314; r2 = 0; r0 = r6.findViewById(r0); Catch:{ Exception -> 0x005c } r0 = (android.widget.EditText) r0; Catch:{ Exception -> 0x005c } r0 = r0.getText(); Catch:{ Exception -> 0x005c } r0 = r0.toString(); Catch:{ Exception -> 0x005c } r3 = 8; r4 = r0.length(); Catch:{ Exception -> 0x005c } r0 = r0.substring(r3, r4); Catch:{ Exception -> 0x005c } r3 = r6.f; Catch:{ Exception -> 0x005c } r4 = 0; L_0x0022: r5 = r6.m; Catch:{ Exception -> 0x005c } r5 = r5.length; Catch:{ Exception -> 0x005c } if (r4 >= r5) goto L_0x004d; L_0x0027: r5 = r6.m; Catch:{ Exception -> 0x005c } r5 = r5[r4]; Catch:{ Exception -> 0x005c } r5 = r0.equals(r5); Catch:{ Exception -> 0x005c } if (r5 == 0) goto L_0x004a; L_0x0031: r5 = 2; if (r3 != r5) goto L_0x0042; L_0x0034: r3 = r6.m; Catch:{ Exception -> 0x005c } r5 = 6; r3 = r3[r5]; Catch:{ Exception -> 0x005c } r0 = r0.equals(r3); Catch:{ Exception -> 0x005c } if (r0 == 0) goto L_0x0042; L_0x003f: r0 = 63; return r0; L_0x0042: r0 = r6.a; Catch:{ Exception -> 0x005c } r0 = r0[r4]; Catch:{ Exception -> 0x005c } r6.k = r0; Catch:{ Exception -> 0x005c } r0 = 1; goto L_0x004e; L_0x004a: r4 = r4 + 1; goto L_0x0022; L_0x004d: r0 = 0; L_0x004e: if (r0 != 0) goto L_0x0059; L_0x0050: r0 = r6.n; Catch:{ Exception -> 0x005c } r3 = r6.getString(r1); Catch:{ Exception -> 0x005c } r0.setText(r3); Catch:{ Exception -> 0x005c } L_0x0059: r0 = r6.k; Catch:{ Exception -> 0x005c } return r0; L_0x005c: r0 = r6.n; r1 = r6.getString(r1); r0.setText(r1); return r2; */ throw new UnsupportedOperationException("Method not decompiled: cn.kwaiching.crackme.CrackMe.h():int"); } }
可以看到,除了h()
函数外,反编译结果非常友好。
看起来是要求输入一个日期,对年月日、时刻进行判断,进行一些神秘处理后,执行a(((e() + f()) + g()) + h())
。a()
的逻辑非常简单,就是判断参数是不是34。所以我们的目标就是e() + f()) + g()) + h() == 34
。而这几个函数就是单纯查表,所以直接遍历所有的日期和时刻即可。
然后就开始复制粘贴外加一些替换和修改,得脚本如下:
a = [16, 6, 7, 10, 9, 16, 10, 8, 8, 9, 6, 6] day_table = [5, 10, 8, 15, 16, 15, 8, 16, 8, 16, 9, 17, 8, 17, 10, 8, 9, 18, 5, 15, 10, 9, 8, 9, 15, 18, 7, 8, 16, 6] month_table = [6, 7, 18, 9, 5, 16, 9, 15, 18, 8, 9, 5] year_table = [7, 7, 9, 12, 8, 7, 13, 5, 14, 5, 9, 17, 5, 7, 12, 8, 8, 6, 19, 6, 8, 16, 10, 6, 12, 9, 6, 7, 12, 5, 9, 8, 7, 8, 15, 9, 16, 8, 8, 19, 12, 6, 8, 7, 5, 15, 6, 16, 15, 7, 9, 12, 10, 7, 15, 6, 5, 14, 14, 9] tail_table = ["23to01", "01to03", "03to05", "05to07", "07to09", "09to11", "11to13", "13to15", "15to17", "17to19", "19to21", "21to23"] def xx(year, month, day): if (year == 1989 or year == 2004): day = 31 if (month == 1 or month == 4 or month == 5 or month == 7 or month == 10 or month == 11 or month == 12): year = 1999 if (year <= 1994 and (month == 2 or month == 6 or month == 8)): month = 3 # <= 1994, month[2,6,8] -> 3 if (year >= 1996 and (month == 2 or month == 6 or month == 8)): month = 9 # >= 1996, month[2,6,8] -> 9 if (year == 1995 and (day > month + 2 or month == day)): month = 6 # == 1995 month[<day-2, day] -> 6 return (year, month, day) for year in range(1984, 2007): for month in range(1, 13): for day in range(1, 32): for k in range(len(tail_table)): year_, month_, day_ = xx(year, month, day) #print year_, month_, day_ try: i = 0 i += year_table[(year_ - 1900) % 60] i += month_table[month_ - 1] i += day_table[day_ - 1] if month_ != 2: i += a[k] else: if k != 6: i += a[k] #print i, if i == 34: print year, month, day, tail_table[k] except: pass
运行后给出结果1995 2 3 05to07
,所以答案是1995020305to07
。
[培训]二进制漏洞攻防(第3期);满10人开班;模糊测试与工具使用二次开发;网络协议漏洞挖掘;Linux内核漏洞挖掘与利用;AOSP漏洞挖掘与利用;代码审计。
最后于 2018-12-9 18:09
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