## https://sploitus.com/exploit?id=SAINT:C4918A16B528F26790825558E8BF5A72
Added: 06/26/2015
CVE: [CVE-2015-1328](<https://vulners.com/cve/CVE-2015-1328>)
BID: [75206](<http://www.securityfocus.com/bid/75206>)
### Background
[Overlayfs](<https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt>) is a type of file system for Linux which implements a union mount.
### Problem
In Ubuntu, overlayfs fails to correctly check file permissions when creating new files in the upper filesystem directory. This can be exploited by an unprivileged user to write arbitrary files, leading to command execution with root privileges.
### Resolution
Apply one of the fixes from [Ubuntu](<http://people.canonical.com/~ubuntu-security/cve/2015/CVE-2015-1328.html>).
### References
<http://seclists.org/oss-sec/2015/q2/717>
### Limitations
Exploit works in Ubuntu 12.04, 14.04, 14.10, and 15.04. The kernel must have `**CONFIG_USER_NS=y**` and overlayfs must have the `**FS_USERNS_MOUNT**` flag in order for the exploit to succeed. gcc must be installed on the target.
### Platforms
Linux