3

My last rkhunter scan reported a couple of warnings that deserve to be checked. Main reason for my suspect is that I wasn't on the machine at (03-Apr-2014 01:12:12) ->AM

I googled for understand what's the purpose of the 2 files I mentioned in question title, but I didn't find very helpful answers. Can anybody tell me what's the aim of those files, and maybe also why/when it would be modified by the system itself?

[10:17:11] Warning: The file properties have changed:
[10:17:11]          File: /usr/sbin/sshd
[10:17:11]          Current hash: 900e153506754ceb7b19f3a01a3ad5e36d43d958
[10:17:11]          Stored hash : 55a1a63a46d84eb9d0322f96bd9a61f070e90698
[10:17:11]          Current inode: 149998    Stored inode: 142248
[10:17:11]          Current file modification time: 1396480332 (03-Apr-2014 01:12:12)
[10:17:11]          Stored file modification time : 1360359087 (08-Feb-2013 22:31:27)

[10:17:34] Warning: The file properties have changed:
[10:17:34]          File: /usr/bin/ssh
[10:17:34]          Current hash: 60366d414c711a70f9e313f5ff26213ca513b565
[10:17:34]          Stored hash : 1b410fb0de841737f963e1ee011989f155f41259
[10:17:34]          Current inode: 150030    Stored inode: 142203
[10:17:34]          Current file modification time: 1396480332 (03-Apr-2014 01:12:12)
[10:17:34]          Stored file modification time : 1360359087 (08-Feb-2013 22:31:27)

the apt logs files making me worry, I censored couple of info. Apparently in the 03-Apr-2014 I didn't installed nothing.

Start-Date: 2014-04-01  15:49:18
Commandline:  ***********
Install:  ***********
End-Date: 2014-04-01  15:49:29

Start-Date: 2014-04-08  14:03:52
Commandline:  ***********
Install:  ***********
End-Date: 2014-04-08  14:04:04

By the way I think (hope) they are false positives [edit:not anymore]. Maybe files edited by some process of the system and normally not recorded in the .dat file of rkhunter because I didn't updated. I came here to find some confirmation or some more paranoia.

3
  • 1
    What does your apt log say about upgrades around that time? Do you automatically install security upgrades?
    – Chris Down
    Apr 18, 2014 at 9:51
  • Thankyou for your hint. No i still don't use automatic updates. i edited the question for apt log files - im getting worry é,è
    – lese
    Apr 18, 2014 at 10:23
  • If the ssh and sshd binaries changed by themselves, and you are sure you didn't do it, that seems very suspicious. What kind of server is this?
    – jw013
    Apr 18, 2014 at 16:25

2 Answers 2

1

The hash of the program should NOT change if you did not update your SSH. Also, it shows you the time when the file was modified (03-Apr-2014), so if you did not update openssh packages, it is not a false positive.

4
  • do you think that uninstall openssh purging configuration files, and reinstalling it, could help in anyway to fix what is been made?
    – lese
    Apr 18, 2014 at 12:26
  • Configuration files will have nothing to do with this. It's only 2 binary files that got changed, so only reinstalling the old version of the package will do. Modification date/time will be when the package was packaged, not installed.
    – phoops
    Apr 18, 2014 at 14:24
  • ok thanks, and when the process of packaging the package usually happens? i guess right after an upgrade or a fresh install, but not hours later, right?
    – lese
    Apr 18, 2014 at 14:45
  • 1
    when "packaging" I mean when Debian packages it before releasing to repositories. But I am not sure on that, you need to test it yourself.
    – phoops
    Apr 18, 2014 at 19:46
1

Google brouth me here. I guess I was also hacked. Same message from rkhunter. Here are some ways to analyze a little further.

To be sure, you can check the md5sum with

sudo cat /var/lib/dpkg/info/openssh-client.md5sums
md5sum /usr/bin/ssh

Another way is

dpkg --verify openssh-server

empty is ok, you have problems if you see ??5?????? /usr/sbin/sshd

You can also install debsums which makes it easier to check

sudo apt-get install debsums
sudo debsums | grep -v OK

This was my list. I think it's still using local sums. Would be more secure if it can be done with an official debian mirror. Does somebody know how to do this?

debsums: missing file /usr/include/openssl/x509_vfy.h (from libssl-dev:amd64 package)
debsums: missing file /usr/include/openssl/x509v3.h (from libssl-dev:amd64 package)
/usr/bin/scp                                                              FAILED
/usr/bin/sftp                                                             FAILED
/usr/bin/ssh                                                              FAILED
/usr/bin/ssh-add                                                          FAILED
/usr/bin/ssh-agent                                                        FAILED
/usr/bin/ssh-keygen                                                       FAILED
/usr/bin/ssh-keyscan                                                      FAILED
/usr/sbin/sshd                                                            FAILED
/usr/bin/rkhunter                                                         FAILED

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.