On Tue, Feb 03 2015 at 14:57, F Rafi wrote: > Hi folks, > > <n00b alert> > > I have auditing for outbound connect requests working using the Connect > (sys_connect) syscall on a server running *Ubuntu precise 12.04 LTS*. > > The rule I'm using is: > > -a exit,always -F arch=b64 -S connect -k network_outbound > > > > I'm getting a substantial amount of saddr=0100.... logs, which I understand > are not connections to a remote host but rather a local AF_UNIX socket > pointing to a file. Example log message is: > > > > type=SYSCALL msg=audit(1423002916.796:24545371): arch=c000003e syscall=42 >> success=no exit=-2 a0=294 a1=7fff97f62680 a2=6e a3=7fff97f62860 items=0 >> ppid=20546 pid=21439 auid=4294967295 uid=33 gid=33 euid=33 suid=33 fsuid=33 >> egid=33 sgid=33 fsgid=33 tty=(none) ses=4294967295 comm="apache2" >> exe="/usr/lib/apache2/mpm-prefork/apache2" key="network_outbound" > > type=SOCKADDR msg=audit(1423002916.796:24545371): *saddr=0100*<truncated to >> remove the hex-encoded file path> > > > Is there an easy way to filter these out so that we only have saddr=0200... > messages left? > > I'm exporting the log to an external syslog server and it would help > considerably if I could eliminate this from all of our servers. > > I see that auditctl has a *filetype* filter which can be set to filter > *socket* or *file* types. Is that the right way to filter these messages? > > -a exit,always -F arch=b64 -F filetype=socket -S connect -k network_outbound does -F filetype!=socket work? > The above rule filters out everything but the af_unix connect syscalls, > which is the opposite of what I'm looking for. > > Any help would be appreciated. > > Thanks, > Farhan > -- > Linux-audit mailing list > Linux-audit(a)redhat.com > https://www.redhat.com/mailman/listinfo/linux-audit

Correction. Both filetype=socket and !=socket result in just saddr=0100.. events. Seems like this is not the way to go. Farhan On Tue, Feb 3, 2015 at 6:24 PM, F Rafi <farhanible(a)gmail.com&gt; wrote: > Sorry, I should have mentioned that I already tried that. That results in > no logs being generated for that rule. > > Thanks, > Farhan > > On Tue, Feb 3, 2015 at 6:21 PM, Peter Moody <pmoody(a)google.com&gt; wrote: > >> >> On Tue, Feb 03 2015 at 14:57, F Rafi wrote: >> > Hi folks, >> > >> > <n00b alert> >> > >> > I have auditing for outbound connect requests working using the Connect >> > (sys_connect) syscall on a server running *Ubuntu precise 12.04 LTS*. >> > >> > The rule I'm using is: >> > >> > -a exit,always -F arch=b64 -S connect -k network_outbound >> > >> > >> > >> > I'm getting a substantial amount of saddr=0100.... logs, which I >> understand >> > are not connections to a remote host but rather a local AF_UNIX socket >> > pointing to a file. Example log message is: >> > >> > >> > >> > type=SYSCALL msg=audit(1423002916.796:24545371): arch=c000003e >> syscall=42 >> >> success=no exit=-2 a0=294 a1=7fff97f62680 a2=6e a3=7fff97f62860 >> items=0 >> >> ppid=20546 pid=21439 auid=4294967295 uid=33 gid=33 euid=33 suid=33 >> fsuid=33 >> >> egid=33 sgid=33 fsgid=33 tty=(none) ses=4294967295 comm="apache2" >> >> exe="/usr/lib/apache2/mpm-prefork/apache2" key="network_outbound" >> > >> > type=SOCKADDR msg=audit(1423002916.796:24545371): >> *saddr=0100*<truncated to >> >> remove the hex-encoded file path> >> > >> > >> > Is there an easy way to filter these out so that we only have >> saddr=0200... >> > messages left? >> > >> > I'm exporting the log to an external syslog server and it would help >> > considerably if I could eliminate this from all of our servers. >> > >> > I see that auditctl has a *filetype* filter which can be set to filter >> > *socket* or *file* types. Is that the right way to filter these >> messages? >> > >> > -a exit,always -F arch=b64 -F filetype=socket -S connect -k >> network_outbound >> >> does -F filetype!=socket work? >> >> > The above rule filters out everything but the af_unix connect syscalls, >> > which is the opposite of what I'm looking for. >> > >> > Any help would be appreciated. >> > >> > Thanks, >> > Farhan >> > -- >> > Linux-audit mailing list >> > Linux-audit(a)redhat.com >> > https://www.redhat.com/mailman/listinfo/linux-audit >> > >

On Wed, Feb 4, 2015 at 8:19 PM, F Rafi <farhanible(a)gmail.com <javascript:;>> wrote: > After some log analysis it looks like filtering on "a2=10" only shows > network activity. From what I understand, this is the address length (int > addrlen) argument in the sys_connect function. > > Traced it down to this comment in socket.c. Sounds like filtering for a2=10 > and a2=18 (to account for IPv6) may work. > > #define MAX_SOCK_ADDR 128 > /* 108 for Unix domain - > 16 for IP, > 16 for IPX, > 24 for IPv6, > about 80 for AX. > 25 must be at least one bigger than the AF_UNIX size (see netunix/af_unix.c > :unix_mkname()) > */ > > 10 hex = 16 dec and 18 hex = 24 dec > > I hope someone can correct me if I sound like I'm not all there. [Ooops, hit "reply" instead of "reply-to-all"] A few things come to mind with this approach: * This will not work on x86 due to the socketcall() syscall multiplexer. * This doesn't solve the problem for applications that leverage the address family independent sockaddr_storage structure. -- paul moore www.paul-moore.com

On Thu, Feb 5, 2015 at 10:31 AM, F Rafi <farhanible(a)gmail.com&gt; wrote: > Ahh..thanks Paul! > > Is there a better way to intercept outbound network access calls while > avoiding af_unix? I'm not sure, I'm not overly familiar with the auditd/auditctl filtering capabilities. There are several people on this list that are far more knowledgeable about that than me. > I assume sockaddr_storage is just a different size (I think 128?) The idea behind the sockaddr_storage struct was to create a structure that could be used to represent any address family that the system supports. I don't believe there is a standard size across OSes due to different level of support, padding, etc; in other words, it's probably best not to rely on a specific size of sockaddr_storage. -- paul moore www.paul-moore.com

I did some digging and now I understand the different size variations of sockaddr_storage. I guess I can just filter on a2!=6e then. And we'd have to keep an eye out for x86 systems. I understand that x86_64 does not use socketcall() but, do you know if multiarch support somehow >allows 32bit apps on x86_64 to use / translate these calls? Thanks again! Farhan On Thu, Feb 5, 2015 at 10:38 AM, Paul Moore <paul(a)paul-moore.com&gt; wrote: > On Thu, Feb 5, 2015 at 10:31 AM, F Rafi <farhanible(a)gmail.com&gt; wrote: >> Ahh..thanks Paul! >> >> Is there a better way to intercept outbound network access calls while >> avoiding af_unix? > > I'm not sure, I'm not overly familiar with the auditd/auditctl > filtering capabilities. There are several people on this list that > are far more knowledgeable about that than me. > >>>> I assume sockaddr_storage is just a different size (I think 128?) > > The idea behind the sockaddr_storage struct was to create a structure > that could be used to represent any address family that the system > supports. I don't believe there is a standard size across OSes due to > different level of support, padding, etc; in other words, it's > probably best not to rely on a specific size of sockaddr_storage. > >>> -- > paul moore > www.paul-moore.com