Ubuntu 14.04/15.10 - User Namespace Overlayfs Xattr SetGID Privilege Escalation

Source: http://www.halfdog.net/Security/2016/UserNamespaceOverlayfsXattrSetgidPrivilegeEscalation/ Introduction Problem description: Linux user namespace allows to mount file systems as normal user, including the overlayfs. As many of those features were not designed with namespaces in mind, this...