Netkit FTP Server: Privilege escalation

Background

net-ftp/netkit-ftpd is the Linux Netkit FTP server with optional SSL support.

Description

Paul Szabo reported that an incorrect seteuid() call after the chdir() function can allow an attacker to access a normally forbidden directory, in some very particular circumstances, for example when the NFS-hosted targetted directory is not reachable by the client-side root user. Additionally, some potentially exploitable unchecked setuid() calls were also fixed.

Impact

A local attacker might craft his home directory to gain access through ftpd to normally forbidden directories like /root, possibly with writing permissions if seteuid() fails and if the ftpd configuration allows that. The unchecked setuid() calls could also lead to a root FTP login, depending on the FTP server configuration.

Workaround

There is no known workaround at this time.

Resolution

All Netkit FTP Server users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-ftp/netkit-ftpd-0.17-r4"