On Sun, Jan 1, 2012 at 4:57 PM, Rilindo Foster rilindo@me.com wrote:
On Jan 1, 2012, at 5:23 PM, Bennett Haselton bennett@peacefire.org wrote:
(Sorry, third time -- last one, promise, just giving it a subject line!)
OK, a second machine hosted at the same hosting company has also
apparently
been hacked. Since 2 of out of 3 machines hosted at that company have
now
been hacked, but this hasn't happened to any of the other 37 dedicated servers that I've got hosted at other hosting companies (also CentOS,
same
version or almost), this makes me wonder if there's a security breach at this company, like if they store customers' passwords in a place that's been hacked. (Of course it could also be that whatever attacker found an exploit, was just scanning that company's address space for hackable machines, and didn't happen to scan the address space of the other
hosting
companies.)
So, following people's suggestions, the machine is disconnected and
hooked
up to a KVM so I can still examine the files. I've found this file: -rw-r--r-- 1 root root 1358 Oct 21 17:40 /home/file.pl which appears to be a copy of this exploit script: http://archive.cert.uni-stuttgart.de/bugtraq/2006/11/msg00302.html Note the last-mod date of October 21.
No other files on the system were last modified on October 21st. However there was a security advisory dated October 20th which affected httpd:
http://mailinglist-archive.com/centos-announce/2011-10/00035-CentOSannounce+...
https://rhn.redhat.com/errata/RHSA-2011-1392.html
and a large number of files on the machine, including lots of files in */ usr/lib64/httpd/modules/* and */lib/modules/2.6.18-274.7.1.el5/kernel/* , have a last-mod date of October 20th. So I assume that these are files which were updated automatically by yum as a result of the patch that
goes
with this advisory -- does that sound right?
So a couple of questions that I could use some help with:
- The last patch affecting httpd was released on October 20th, and the
earliest evidence I can find of the machine being hacked is a file dated October 21st. This could be just a coincidence, but could it also
suggest
that the patch on October 20th introduced a new exploit, which the
attacker
then used to get in on October 21st? (Another possibility: I think that when yum installs updates, it doesn't actually restart httpd. So maybe even after the patch was installed, my old httpd instance kept running and was still vulnerable?
As
for why it got hacked the very next day, maybe the attacker looked at the newly released patch and reverse-engineered it to figure out where the vulnerabilities were, that the patch fixed?)
- Since the */var/log/httpd/* and /var/log/secure* logs only go back 4-5
weeks by default, it looks like any log entries related to how the
attacker
would have gotten in on or before October 21st, are gone. (The secure* logs do show multiple successful logins as "root" within the last 4
weeks,
mostly from IP addresses in Asia, but that's to be expected once the machine was compromised -- it doesn't help track down how they originally got in.) Anywhere else that the logs would contain useful data? _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Do you have SELinux enabled? If not, you might need to turn that on, as that would have prevented that exploit.
I don't, but I'm not sure what you mean by "that would have prevented that exploit". How do you know what exploit they used, much less that SELinux would have prevented it?
Or are you assuming that my guess was correct that they got in because of a vulnerability that was opened up by the patch being auto-installed on 10/20, and that if *that* is the case, that SELinux would have prevented that? How does that work, how would SELinux have prevented a vulnerability being opened up by the patch install?
Bennett