From Zero To X

zTrix's Blog



总共发现了至少 5 个不同的盗版打包,其中包名为 com.rayxyj.stacker 的盗版上线最早,下载量和用户使用都最大,因此就拿这个盗版版本开刀。

这家盗版在多个市场都有投放,比如 ,并且表明了开发者来源是掌赢科技有限公司,下载次数应该已经上千,在最近的数据统计中,使用的用户占比 12.25%,因此是一个比较典型的案例。

这个盗版版本基于的是我的 1.4 版本重打包。后续我又发布了 1.6 版本,他们并没有跟进。


3 年前的一个月黑风高夜,大家都还很年轻,我们几个小朋友聚在一起,想尝试做点 Android 游戏开发。我拉来了同班同学诚哥,拉来了高中同学张光耀。两个程序员加一个美工,开始了一番离奇刺激又不乏艰辛的奇幻旅程。

大家一番讨论之下,决定做一款简单好玩的益智类游戏。我一拍大脑想到了几年前曾经玩过的一个叫做 superstacker2 的 Flash 游戏(现在这个游戏已经有了 Android 版本,当时还没有,想玩 Flash 原版请戳这里 ),于是想把这个游戏做到手机上一定很好玩,而且,我们可以增加重力感应关卡,微创新嘛!当然我们还想了其他很多乱七八糟好玩又离奇的功能,但是最终都没有付诸实践。

The Power of PEDA - ASIS CTF Quals 2014 Serial Number Writeup

by Wenlei Zhu (zTrix@blue-lotus)

Again, another ELF x86_64 binary with very long bit operation logic asking for some serial number.

I can still remember the time trying to solve Turututu, during which I spent a lot of time trying to figure out what happened under the instructions, but sadly with no luck, it’s totally a mess. The lucky thing is that peda is really a powerful tool, and I can guess the hidden logic with the help of peda, so I finally solved Turututu.

So let’s show what a powerful tool peda is by solving this challenge without figuring out that long bit operation logic(over 1 thousand lines of asm code!).

BCTF 2014 决赛题 - Secret Guard 回顾与分析

by Wenlei Zhu (zTrix@blue-lotus)

secret-guard 作为 BCTF 2014 决赛中最简单的一道 binary 题目,设计目标为,能够在放出后 4 个小时左右被各队逐渐解出,达到一波得分高潮。漏洞设置方面,设置了 3 个不同类型的简单漏洞,分别属于信息泄露、栈溢出和命令注入,期望是各个队伍发现不同的漏洞,达到互有攻防,反复抢占阵地的激烈效果。

根据比赛的实际情况来看,题目足够简单,作为最简单的 binary 题目,4 个小时内被解出的目标完成了,但是没有想到的是,在很长的一段时间内,只有 HITCON 217 一个队伍解出这道简单题目,并且只利用了其中命令注入的最简单漏洞。赛后的交流得知,开始时很多人以为每个题目只有一个漏洞,于是找到漏洞之后,就去看别的题目了,没有再仔细研究这个题目。另外,不知道是由于此题攻击流量分析较为困难还是各个队伍经验较少的原因,所有其他队伍一直处于被打状态而没有及时修补,导致得分差距太大,所以总体感觉甚为惋惜,花费心思设置的各个漏洞和坑点大家都没有遇到,也没有达到预期的效果。


PlaidCTF 2014 - Parlor (Crypto 250) Writeup

by Wenlei Zhu (zTrix@blue-lotus)

Problem description

Crypto (250 pts)

The Plague is running a betting service to build up funds for his massive empire. Can you 
figure out a way to beat the house? The service is running at

Codegate CTF Final 2014 Memory

by Wenlei Zhu (zTrix@blue-lotus)

Last week, We represented team blue-lotus, consisting of me(zTrix), cbmixx, Aluex, Adrian, fqj and our beautiful photographer as well as translator, at Codegate CTF Finals 2014, in Seoul, South Korea. It’s really a wonderful experience.

Since we are close to Seoul, we took off at April 1st, just one day before the game.

Let’s Make License Social! The Star and Thank Author License (SATA License)

by Wenlei Zhu

There are many licenses out there for open source software. GPL, MIT License, Apache License are most popular ones among them.

When creating projects on github/google code, there even is an option for people to choose the most popular licenses.

But to me, those licenses are boring, and for most of the time, I think, nobody care about them, very few people can distinguish them. Actually, it’s just put into a project occupying an embarrassing position, maybe just to make a project feels more like a formal one, and in active developing.

Why not make those licenses more interesting, and attach some social functions for developers?

Codegate CTF 2014 Quals - Weirdshark Writeup

by Wenlei Zhu (zTrix@blue-lotus)

A pcap file is given here for analysis. check type using file

# file weird_shark.pcap_f5f1e42dd398f18c43af89ba972b3ee7
weird_shark.pcap_f5f1e42dd398f18c43af89ba972b3ee7: pcap-ng capture file - version 1.0

Open the file using wireshark, but no luck, wireshark reports malformed file format and refuse to open it.

So we need to extract the packets inside manually.

PHDays CTF IV Quals 2014 - Turututu Writeup

by Wenlei Zhu (zTrix@blue-lotus)

turututu is an ELF 64-bit executable, after some investigation, it’s easy to find out that the task.exe is a native binary generated using ocamlopt.

I know little about ocaml, so at first I searched a lot trying to get some bytecode or decompiler stuff, or some dedicated debugger for ocaml, but none of these tools could be found.

So it’s time to dive into assembly.

Defcon 20 小记

6 月 2 号到 4 号有幸加入 blue-lotus 参加了 defcon CTF 2012 的比赛,感慨颇深。清华第一次组队参加这个比赛,虽然没进决赛,但第一次参赛能进前 20,也算不错的成绩了。

MooseFS metadata.mfs 数据恢复纪实

从这周四下午到周六早上这 40 个小时真是紧张惊险又刺激。以至于我要写篇 blog 来记录一下。

数据丢失! 天灾人祸!

实验室跑了一套自己的网盘系统,其中后台数据存储用的是 Moosefs 网络分布式文件系统。这个系统用起来一直很好,直到 2 天前…

Trip to the Silicon Valley


3 月 4 号坐上了 Boeing 747,飞机真的很大。人不多,我那一排 3 个座位就我一个人,于是睡得很舒服。






预约是很纠结的一件事情。尤其是我预约的时候是 1 月 19 左右,当时在家,只好请还在北京的同学帮忙去中信银行买了一下加密电话卡,付了签证费用。

第一次打电话还算顺利,准备好各个号码之后,拨通电话,预约日期只有 1 月 27 到 1 月 31 号可以选,2 月好像还没开始。于是预约了 30 号。