I'm using pam_oath.so to control sudo access. The following line appears
in my /etc/pam.d/sudo:
auth sufficient pam_oath.so usersfile=/etc/users.oath window=5 digits=8
It works well, and has done since time out of mind. I've recently
noticed, however, that having a user authenticate via a HOTP OATH token
not only causes the /etc/users.oath file to be updated (which makes sense,
the stored counter needs to be incremented) but also have its
group-ownership changed to the primary group of the last user who sudoed.
The file has no group read- or writeability, but it still strikes me as
weird, and if the group modes were not -rwx, it might be a vulnerability.
Does anyone else use HOTP OATH via PAM, and see this? Is there a good
reason for it?
[me@dormouse ~]$ ls -la /etc/users.oath
-rw-------. 1 root root 550 Jun 4 10:31 /etc/users.oath
[me@dormouse ~]$ sudo -l
One-time password (OATH) for `me':
[...]
User me may run the following commands on dormouse:
(ALL) ALL
[me@dormouse ~]$ ls -la /etc/users.oath
-rw-------. 1 root me 550 Jun 4 10:33 /etc/users.oath
--
Tom Yates - https://www.teaparty.net
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