Portshell crypto trickery

I re-polished some of my old tools and imported them
to github. This time it was psc.

The port-shell crypter (psc) allows you to 'upgrade'
previously unencrypted sessions, no matter whether
its a multi-hop SSH session, a portshell without a tty,
telnet, rlogin or minicom.
It gives you a full pty with end-to-end encryption.

You can also use it as a kind of two-factor authentication
with SSH, if you add psc-remote as shell inside
/etc/passwd or use OpenSSH's ForcedCommand option.

Tunnel trickery

I just added fraud-bridge to my github. It was worth
coding even if there exist a lot of DNS and ICMP
tunneling tools.

Features:

o tunneling of TCP-connections, keeping TCP-state
o via DNS: on UDP or UDP on IPv6
o via ICMP or ICMPv6
o HMAC (MD5) protecting of tunnel content
o transparently patching announced TCP-MSS to prevent
  fragmentation or DNS packet splitting
o using EDNS0 extension for DNS-tunneling to achieve good
  througput (larger DNS TXT-replies fit into one reply, honouring
  announced MSS)
o cope with bind9 limits/quota and still having good latency
  for interactive sessions and good throughput
o once started as root, continues to run as unprivileged user
  inside a chroot

If you want to know how a fraud-bridge looks like, check
current blog entry picture, taken during one of my lost-places
tours.

OpenSSL PrivSep trickery

During this years hackweek, I implemented a
OpenSSL PrivSep. It's far from complete, but it features most
of the SSL functions you need to run a SSL server
or client. It also features the seccomp sandbox,
so all the dirty SSL handshake and protocol/parsing is done
in a confined process.

I used my research webserver project, lophttpd to
demonstrate on how it works.
Basically you just include two header files,
provide a callback named privsep_init() and tell
the PrivSeped process, which is started at the
time you call any of the OpenSSL init functions,
when to actually drop the privileges with
SSL_privsep_ctrl(PRIVSEP_DROP_PRIV). And thats it.

You can copy the *.c and *.h files from the sslps
git repo to the lophttpd dir and make -f Makefile.sslps
Do not mind the warnings about the redefinitions
of certain OpenSSL macros, they need to be replaced
in order to proxy all the SSL_ functions to the
confined process.

Fear my drawing skills and have a look at the whole picture
so its easier to understand :)

Nirvana trickery

We miss you Kurt, your music is an endless source of
power for creating the 90's exploits.

YEAAAAAAAAAAAAAA\x41\x41\x41\x41\x41\x41\x41YYYYYYY! (at 2:22 !!)

CLONE_NEWUSER trickery: CVE-2013-1858

Recent kernels (3.8+ something) introduced a feature called
user-namespaces (user-ns, CLONE_NEWUSER flag)
in which you can have your own UID 0.
Think of it as a container solution, so you can
set up compartments on a host. A nice thing,
but it has some security implications. In particular
if you mix this feature with CLONE_FS, which means
that the file-system state is shared between the
containers (e.g. processes). You suddenly get this:

The problem here is that parent and child share the
FS info (the chroot in this case), but only the child
has got its own user-ns. Since it has the
capability to do the chroot() in its own user-ns,
it will succeed doing the chroot() syscall but due to
CLONE_FS, it will also affect the parent.
Parent however stays in the init user-ns (the user-ns
that is default upon boot and the namespace where you
want to have root).
Getting a rootshell from inside a user controlled chroot
with help from outside processes is straight forward.

The xSports can be found here.

Update:
A CVE has been assigned (CVE-2013-1858) and a patch was made.

c25k problem solved

Although the c10k problem is not really a problem in
Computer Science anymore, I successfully solved the
c25k problem (and I am not talking about exploit prices)
for myself.

lophttpd can handle even more connections on a commodity PC,
single core, without connection drops. If your network equipment 
is just good enough (GBit patch cable!:)

I added a new -s switch that lets you experiment with different
scheduling strategies if the TCP send buffers start to fill.
Nevertheless, as poll() will not report a POLLOUT revent
if the TCP send buffer is full, the none stragegy should just be fine. 
Other strategies are minimize (reduce chunksize to minimum)
or suspend (temporarily remove client from POLLOUT list, if
TCP send buffer has data from last send). In particular the
suspend strategy may be of interest, as it reduces the
amount of poll events that the kernel needs to check for.
However, I could not measure any real benefit. Probably one
reason more to say that c10k is not a problem anymore since
quite a lot of time.

Interestingly: lophttpd, if under load, can even utilize
more than 100% CPU:

lophttpd caching trickery

I added 404-caching to lophttpd, in the hope that
it will result in overall speedup if a lot of clients
try to fetch non-existing files (favicon.ico etc.)

The key for the cache is the first line that is sent,
so once we see this request again, we dont need to parse the
entire header, decode the pathname and stat() it before we send
the error reply. Good, eh?

Valentine pam_fprintd trickery

Anyone can give your finger by spoofing DBUS signals
to pam_fprintd, effectively bypassing fprintd authentication.
Tested with fprintd 0.41.
darklena is the PoC and the authors have been informed.

Its probably about time to check dbus-glib usage or usage
of DBUS signals in privileged code in general.

[Update:] successfully tested on a vanilla FC16 setup with
fprintd installed from repository and SELinux target config
left as-is:

grep vs. grab

I pushed my experimental grep version to github.
It features only small amount of options, but it speeds
out grep's on large directory trees, in particular if
you have a fast HDD or SSD, where you can be as
twice as fast.

What is a dzug?

I moved the dzug.c from the null directory to xSports,
where it actually belongs to.

What is a D-Zug? Besides being an exploit for CVE-2012-3524,
a D-Zug (german: Durchgangs-Zug) was a fast kind of train
in the 70's and 80's. Nowadays its obsoleted by high speed
trains like ICE (similar to TGV in France).
dzug.c, also kind of a 80's style of living, integrates a lot of
attack vectors to proof CVE-2012-3524 exploitable.
There exist a lot of flavors of dzug.c, so
if this PoC version is not working for you, it means
indeed nothing. Its also not bound to Linux. Theoretically any
UNIX running DBUS is at risk.