strange arguments in some EXEC audit events

strange arguments in some EXEC audit events

[Nikola Ciprich]

Hello,
I'd like to ask about one thing regarding audit I don't understand:
We are running auditd configured to log some syscalls (ie exec) and everything works fine, but quite often we're getting
some strange records:
type=SYSCALL msg=audit(1236001721.608:55239): arch=c000003e syscall=59 success=yes exit=0 a0=7f1407a74653 a1=7fff1088d710 a2=12cf580 a3=7f1408884770 items=2 ppid=20278 pid=23246 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts4 ses=25 comm="sh" exe="/bin/bash" subj=kernel key=(null)
type=EXECVE msg=audit(1236001721.608:55239): argc=3 a0="sh" a1="-c" a2=66696C65202D4C202F7661722F6C6F672F61756469742F61756469742E6C6F6720323E2F6465762F6E756C6C
type=CWD msg=audit(1236001721.608:55239):  cwd="/var/log/audit"
type=PATH msg=audit(1236001721.608:55239): item=0 name="/bin/sh" inode=97403 dev=08:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 obj=unlabeled
type=PATH msg=audit(1236001721.608:55239): item=1 name=(null) inode=63681 dev=08:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 obj=unlabeled
type=SYSCALL msg=audit(1236001721.609:55240): arch=c000003e syscall=59 success=yes exit=0 a0=11ee410 a1=11ee9d0 a2=11ed260 a3=0 items=2 ppid=23246 pid=23247 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts4 ses=25 comm="file" exe="/usr/bin/file" subj=kernel key=(null)

I'm not sure what "66696C65202D4C202F7661722F6C6F672F61756469742F61756469742E6C6F6720323E2F6465762F6E756C6C" argument might be, is it somehow encoded string? It seems to remain unchanged across multiple events...
Could somebody shed some light on it for me?
Thanks a lot in advance!
BR
nik

-- 
-------------------------------------
Nikola CIPRICH
LinuxBox.cz, s.r.o.
28. rijna 168, 709 01 Ostrava

tel.:   +420 596 603 142
fax:    +420 596 621 273
mobil:  +420 777 093 799
www.linuxbox.cz

mobil servis: +420 737 238 656
email servis: servis@linuxbox.cz
-------------------------------------

Re: strange arguments in some EXEC audit events

[Eric Paris]

On Mon, 2009-03-02 at 15:17 +0100, Nikola Ciprich wrote:
> Hello,
> I'd like to ask about one thing regarding audit I don't understand:
> We are running auditd configured to log some syscalls (ie exec) and everything works fine, but quite often we're getting
> some strange records:
> type=SYSCALL msg=audit(1236001721.608:55239): arch=c000003e syscall=59 success=yes exit=0 a0=7f1407a74653 a1=7fff1088d710 a2=12cf580 a3=7f1408884770 items=2 ppid=20278 pid=23246 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts4 ses=25 comm="sh" exe="/bin/bash" subj=kernel key=(null)
> type=EXECVE msg=audit(1236001721.608:55239): argc=3 a0="sh" a1="-c" a2=66696C65202D4C202F7661722F6C6F672F61756469742F61756469742E6C6F6720323E2F6465762F6E756C6C
> type=CWD msg=audit(1236001721.608:55239):  cwd="/var/log/audit"
> type=PATH msg=audit(1236001721.608:55239): item=0 name="/bin/sh" inode=97403 dev=08:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 obj=unlabeled
> type=PATH msg=audit(1236001721.608:55239): item=1 name=(null) inode=63681 dev=08:01 mode=0100755 ouid=0 ogid=0 rdev=00:00 obj=unlabeled
> type=SYSCALL msg=audit(1236001721.609:55240): arch=c000003e syscall=59 success=yes exit=0 a0=11ee410 a1=11ee9d0 a2=11ed260 a3=0 items=2 ppid=23246 pid=23247 auid=0 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=pts4 ses=25 comm="file" exe="/usr/bin/file" subj=kernel key=(null)
> 
> I'm not sure what "66696C65202D4C202F7661722F6C6F672F61756469742F61756469742E6C6F6720323E2F6465762F6E756C6C" argument might be, is it somehow encoded string? It seems to remain unchanged across multiple events...
> Could somebody shed some light on it for me?
> Thanks a lot in advance!

It's a hex representation of the actual bits sent to audit.  In this
case it is a string which contains the space character.  Since we don't
really trust use strings when they contain non-letters we encode it like
this.  This translates to "file -L /var/log/audit/audit.log 2>/dev/null"

http://www.dolcevie.com/js/converter.html does a nice easy conversion...

Re: strange arguments in some EXEC audit events

[Steve Grubb]

On Monday 02 March 2009 09:17:44 am Nikola Ciprich wrote:
> I'm not sure what
> "66696C65202D4C202F7661722F6C6F672F61756469742F61756469742E6C6F6720323E2F64
>65762F6E756C6C" argument might be, is it somehow encoded string? It seems to
> remain unchanged across multiple events... Could somebody shed some light
> on it for me?

You should be able to see the record's text by using ausearch with the -i 
option. If ausearch is not displaying it correctly with that option, then you 
have found a bug.

-Steve

Re: strange arguments in some EXEC audit events

[Nikola Ciprich]

Hi,
as Eric suggested, message was relly just encoded, thus
everything seems to work as expected.
Thank you both a lot!
nik

On Mon, Mar 02, 2009 at 10:15:42AM -0500, Steve Grubb wrote:
> On Monday 02 March 2009 09:17:44 am Nikola Ciprich wrote:
> > I'm not sure what
> > "66696C65202D4C202F7661722F6C6F672F61756469742F61756469742E6C6F6720323E2F64
> >65762F6E756C6C" argument might be, is it somehow encoded string? It seems to
> > remain unchanged across multiple events... Could somebody shed some light
> > on it for me?
> 
> You should be able to see the record's text by using ausearch with the -i 
> option. If ausearch is not displaying it correctly with that option, then you 
> have found a bug.
> 
> -Steve
> 

-- 
-------------------------------------
Nikola CIPRICH
LinuxBox.cz, s.r.o.
28. rijna 168, 709 01 Ostrava

tel.:   +420 596 603 142
fax:    +420 596 621 273
mobil:  +420 777 093 799
www.linuxbox.cz

mobil servis: +420 737 238 656
email servis: servis@linuxbox.cz
-------------------------------------