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Old 11-25-2004, 07:42 PM   #1
Whitestone
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Question chkrootkit and possible trojan


Hi, all.

I ran chkrootkit and found a four things I don't understand. (I'm a newbie.)

Here are the entries:

Checking `wted'... 8 deletion(s) between Mon Nov 1 02:08:29 2004 and Thu Nov 30 05:09:39 2023

Also:

Checking `sniffer'... eth0: PF_PACKET(/sbin/dhclient)

This one:

Checking `lkm'... You have 2 process hidden for ps command
Warning: Possible LKM Trojan installed

(How do I tell a false positive from the real thing?)

and this:

Searching for suspicious files and dirs, it may take a while...
/usr/lib/perl5/5.8.0/i386-linux-thread-multi/.packlist
/usr/lib/openoffice/share/gnome/net/.directory
/usr/lib/openoffice/share/gnome/net/.order
/usr/lib/openoffice/share/kde/net/applnk/OpenOffice.org/.directory
/usr/lib/openoffice/share/kde/net/applnk/OpenOffice.org/.order
/usr/lib/qt-3.1/etc/settings/.qtrc.lock
/usr/lib/qt-3.1/etc/settings/.qt_plugins_3.1rc.lock

I'm grateful for any insight and assistance you can provide. How do I determine if there really is a threat, and what do I do about it if there is?

Whitestone
 
Old 11-26-2004, 12:46 AM   #2
Capt_Caveman
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Re: chkrootkit and possible trojan

Checking `wted'... 8 deletion(s) between Mon Nov 1 02:08:29 2004 and Thu Nov 30 05:09:39 2023
This is usually an indication that someone has attempted to edit the system logs to hide their accessing the system. Often a sign of security compromise (gain access then hose logs after rooting/backdooring), though having log corruption can cause a false positive. The fact that the date is about 20 years from now usually suggests that's the case. Post the output of last -aix .

Checking `sniffer'... eth0: PF_PACKET(/sbin/dhclient)
A PF_PACKET socket is a low level connection that bypasses normal parts of the network stack and allows sniffing of network traffic. Again a sniffer is usually an indication of a system compromise, but this check is subject to false positives. The most common false positive is mistaking the dhclient listening on a PF_PACKET socket for dhcp traffic as a sniffer. Looks like that is what you're seeing here. If you're on a rpm-based system, you can verify the package integrity of the dhclient rpm to be sure that it isn't trojan, but this is a very common false positive.

Checking `lkm'... You have 2 process hidden for ps command
Warning: Possible LKM Trojan installed

Having processes hidden from the ps command can be indicative of trojaning or presence of an LKM rootkit. However, this is a very common false positive message as well. This check compares the output of ps with the open file descriptors in /proc , so if a short-lived process terminates between these two checks, then the process will be flagged. Use the chkrootkit helper app and run:

chkproc -v

This should output the process id numbers (PID), and then check their identities with:

cd /proc/PID/ && cat cmdline

If chkproc -v doesn't return anything then it was likely a false positive. If it still returns PIDs that correspond to abnormal apps or filenames, then post the output.

Searching for suspicious files and dirs, it may take a while...
/usr/lib/perl5/5.8.0/i386-linux-thread-multi/.packlist
<SNIP>

Chkrootkit flags hidden files outside of /home as being suspicious. Visually inspect these and verify they don't contain anything malicious to reduce paranoia level. Judging by their name (extremely cursory and not at all recommended) they appear to be normal, but definitely inspect them to verify.

Last edited by Capt_Caveman; 11-26-2004 at 12:49 AM.
 
Old 11-26-2004, 06:04 AM   #3
m4dj4ck
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Registered: Aug 2004
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Distribution: slackies
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Quote:
Checking `lkm'... You have 2 process hidden for ps command
Warning: Possible LKM Trojan installed
if im not mistaken, i came across this problem before and as capt_caveman cited, this is a very normal false positives. I remembered i ran chkrootkit and it shows the same errors as above and i run this command on gnome-terminal, which means i was using X windows(gnome) that time. Then, i tried to run this command again WITHOUT running X server behind and surprisely, chrootkit stop giving those hidden ps commands. Anyway, Im not sure whether this is the same as your problem. cheers!
 
  


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