这里介绍使用dumpdecrypted砸壳。原理是用DYLD_INSERT_LIBRARIES这个环境变量加载脱壳的动态链接库dumpdecrypted.dylib

　　1.ssh连接上越狱的机器，输入密码alpine

　　　　ssh root@192.168.7.116

　　2.打开要砸的app，ps aux | grep var找到它的目录

yigewangde-iPhone:~ root# ps aux | grep var

mobile    1118   0.0  1.0  1139072   9684   ??  Ss   Wed10AM   5:30.70 /var/containers/Bundle/Application/BCC24500-0986-4343-A287-7BAF60B33E60/WeChat.app/WeChat

root      1913   0.0  0.1   537488    568 s000  S+    9:50AM   0:00.02 grep var

root       474   0.0  0.2   707792   1676   ??  Ss   Tue04PM   0:00.47 /usr/libexec/pkd -d/var/db/PlugInKit-Annotations

mobile    1902   0.0  4.8   900736  47580   ??  Us    9:50AM   0:03.69 /var/containers/Bundle/Application/249A5309-8F1A-4C4A-93FD-E48EEAE00C95/DingTalk.app/DingTalk

　　我们拿DingTalk开刀。

　　3.用scp把dumpdecrypted.dylib 拷贝到 /usr/lib目录下

　　　　scp dumpdecrypted.dylib root@192.168.7.116:/usr/lib

　　4.切换到mobile用户

　　　　su mobile

　　5.切换到/var/mobile/Documents这个目录

　　　　cd /var/mobile/Documents

　　6.开始砸壳

　　　　DYLD_INSERT_LIBRARIES=/usr/lib/dumpdecrypted.dylib /var/containers/Bundle/Application/249A5309-8F1A-4C4A-93FD-E48EEAE00C95/DingTalk.app/DingTalk

　　　　mach-o decryption dumper

　　　　DISCLAIMER: This tool is only meant for security research purposes, not for application crackers.

　　　　[+] detected 64bit ARM binary in memory.

　　　　[+] offset to cryptid found: @0x100084cf8(from 0x100084000) = cf8

　　　　[+] Found encrypted data at address 00004000 of length 40534016 bytes - type 1.

　　　　[+] Opening /private/var/containers/Bundle/Application/249A5309-8F1A-4C4A-93FD-E48EEAE00C95/DingTalk.app/DingTalk for reading.

　　　　[+] Reading header

　　　　[+] Detecting header type

　　　　[+] Executable is a plain MACH-O image

　　　　[+] Opening DingTalk.decrypted for writing.

　　　　[+] Copying the not encrypted start of the file

　　　　[+] Dumping the decrypted data into the file

　　　　[+] Copying the not encrypted remainder of the file

　　　　[+] Setting the LC_ENCRYPTION_INFO->cryptid to 0 at offset cf8

　　　　[+] Closing original file

　　　　[+] Closing dump file

　　7.over了。在/var/mobile/Documents下就可以看到了

ios app 砸壳