root is unable to change file permissions!

[Andreas Hatz]

Hello Debain Users,   We have an interesting phenomenon occuring on one of our servers. We have noticed that two files in the /bin directory have had their executable permissions removed and we are unable to chmod the files as root.   current file permissions: -rw-r--r--   1 root     root        35464 May 31 13:02 /bin/login -rw-r--r--   1 root     root        54152 Aug 29  2001 /bin/netstat   when trying to change permissions:   ns:~# whoami root ns:~# id uid=0(root) gid=0(root) groups=0(root) ns:~# chmod 755 /bin/login chmod: changing permissions of `/bin/login': Operation not permitted We have tried doing the same thing from the rescue disc login prompt. same outcome.   This seems to be a serious security issue. Root user seems to have lost control of some files. Other files can be changed using the above commands.   Any ideas?   Best regards,   Andreas Hatz