pwnable.kr-flag

题目描述: Papa brought me a packed present! let’s open it. Download : http://pwnable.kr/bin/flag This is reversing task. all you need is binary 下载下来之后file一下: ➜ Desktop file flag flag: ELF 64-bit LSB executable, x86-64, version 1 (GNU/Linux), statically linked, stripped 64位的ELF,直接拖到IDA里面看看,发现只有三个函数,而且并不能正常打开,目测是加壳了。于是在里面瞎翻,发现了upx的关键字,果断upx -d flag把壳脱了。重新拖进IDA,发现代码很简单: malloc申请了一个100LL的地址,然后把flag复制进去了,直接查看flag的值,发现直接出现flag了: UPX…? sounds like a delivery service 🙂