Posts Tagged ‘linux’

prads-0.3.2: ya skipped that one

Monday, November 5th, 2012

Ever since HACK.LU (where we spoke about VSF), Ebf0 and I have had quite some activity on PRADS, wonder why?

We really enjoyed the design of POM-NG, we find this little program quite inspiring and will keep in touch with GMsoft.

This might be the right time to announce PRADS-me! at prads.delta9.pl, a service to actively fingerprint your own self. Real useful even just for an IP check, geolocation or to see what types of fingerprints you are matching at any given time.

Some of you might recall that PRADS was the subject of a Masters thesis in 2011: “Investigating Passive Operating System Detection” by Petter Bjerke Falch from UiO. Well, it’s happened again.

Jostein Haukeli at the University of Oslo Department of Informatics has written a paper on “False positive reduction through IDS network awareness”. We are excited about the prospect that our work is being used in data correlation, and we would like to see more event correlation stuff done in a scalable context.

Last year PRADS was a featured ip6-ready tool at the ISC.
Furthermore, in July this year PRADS was included in OSSIM, the Open Source SIEM

In other news, PRADS is about to be baked into the next release of the Security Onion network monitoring linux distro. Version 12.04 beta already comes with PRADS included (replacing old-timers sancp and pads) but it did require some bug-squashing from our end. You know what that means? 0.3.2-rc1 was tagged in the tree recently. That’s right: a new PRADS release is coming up Real Soon Now.

the paranoid console viewer

Tuesday, June 19th, 2012

Hi all,
I know it’s been a while since my last post.
There is lots to talk about, but let’s start afresh with something short and sweet.

Let me paint a picture for you:
There is something broken in the most holy and secure part of your network. You need to call support to have them look at it. The support rep wants console access, but you can’t give them axx to your holiest cream pie.
They offer to take over your desktop with a java rootkit app like TeamViewer, GoToMeeting or WebEx.
You decline. You need to stay in control, but show them what they need to see, that and only that.
How?

Let me be clear on the problem statement:
Read-only shell access to the most secure host, which is not available over the wire, viewed by multiple parties at the same time.

Here’s how to do that with SSH, screen(1) and some foo,
with ssh->chroot->rbash->readonly multiuser screen->reverse ssh->openvpn:

You will need a linux server in an “unsafe” zone which is exposed to your support rep on the internet or thru VPN.

  1. Create the user to be contained on your unsafe box, with the restricted bash shell:
    unsafe# export user=rep; adduser $user; chage -s /usr/bin/rbash $user
  2. (Bonus:) chroot/contain the user within sshd_config
  3. Setup multiuser screen on the unsafe box. There are lots of guides for it, but the short and sweet of it is: unsafe# chmod +s `which screen`; chmod 755 /var/run/screen Indeed, this increases the attack surface, and therefore we call this box the unsafe one.
  4. ssh from secure zone to unsafe server:
    secure# ssh -R 2222:localhost:22 screen
  5. Run screen from YOUR account and do :addacl $user :chacl $user -w "#" :chacl $user -x "?" Replace $user with whatever from step 1. Then, still in your screen: :multiuser on
  6. Win! Now you can reverse ssh back to the secure zone and let $user on the unsafe box read the terminal without being able to access anything but what you show her.
  7. Bonus: Add `screen -r $youraccount` in $user/.profile and $user will drop straight into locked screen, and remember that multiuser screen is read-write-execute for all accounts that are addacl’d
    so you might want to chacl before enabling the $user account login.

    And there you have it, superparanoid reverese secure-unsecure remote shell viewer.

    0k

pixie dust

Thursday, February 2nd, 2012

we’ve booted backtrack off usb before, now that’s kinda
boring and installing backtrack onto the usb with unetbootin
is painfully slow and not the same as bootin strait off the
usb which is what we want in this case; not an install
but a fresh copy every boot

there is someone disagreeing in the back of the room, now
wouldn’t this be a lot more complicated? No sir. on the contrary
booting fresh every time makes work a lot simpler; you gain a
direct relationship to what you store where, and where you
access your data from

but there is another one in the front;you sir, you feel that
one would have to sacrifice many of the comforts such as all
any tools of the trade at hand and permanent local storage -
but at best this is a lazy roadblock to salvation; by booting
off of local storage we have local storage at hand in a more
practical format, be that even a microscopic carrier can be
removed and replaced with sufficient storage for everything
and then some

the medium can be embedded, destroyed or ingested, so
the impermiableness of accidentally recorded data and the
robustness, accessability and portability of removable storage
comes very much in hand upon situations that either require
inconspiciousness, anonymity, covertness, plausible deniability
or a high degree of reliability in day-to-day computing

the totalality of the system given to remaining only in memory
causes it to be independent of other storage for operations, and when
operations cease from loss of any exterior preconditions, the
system simply ceases. when preconditions reoccur – by powering on
and executing the first block – the system can be relied upon to
simply starts afresh, completely unperturbed by any previous history

should the need arise to patch the system; say some new app or
capability is called for where there is no time to rebuild,
a patch should be scripted always when there is certanity that
the capability will require a repeat performance. It is advised
to devise a patch which includes all dependencies.

thus the fresh system becomes more capable and more accessible
over time, just like an install. patches can then easily be
rolled into the system should they proove useful to others.

But how does one do it? Well, it’s easy but unfortunately
not as easy as overwriting the boot device; it’s just not
practical because partitioning is always an individual consideration

  • . there are often other files on the block device
  • . choice of filesystem and memory technology has much bearing
  • . the block device is larger or smaller than expected
  • instead, we allow any bootable partition scheme and any
    filesystem and memory technology, as long as the storage
    requirements of the system are met;

    here’s to clone how:

    cp -a boot/ apt/ casper/ gone/ preseed/ syslinux/ 
    syslinux /dev/partition
    mbr /dev/device
    

    but that’s fine, it’s been done and all, but even the ability to
    boot the system with precisely zilch local storage comes in
    handy, and for that we have pixie dust.

    pixie daemon and tiny ftp should be pointing a path
    exactly matching the dhcp-provided patch.. otherwise
    you will have worries!

    /etc/pxe.conf:

    interface=eth1
    service=X86PC,0,0,local,Local boot
    service=X86PC,0,0,pxelinux,PXELinux
    tftpdbase=/var/lib/tftpboot
    domain=truly.yours
    

    /etc/default/tftpd-hpa:
    TFTP_DIRECTORY=”/var/lib/tftpboot/”

    /etc/dnsmasq.conf:

    dhcp-boot=/var/lib/tftpboot/pxelinux,vulcano,10.10.10.86
    

    “high speed” tftp daemons and multicast can be found but it is
    advised to stick to tftpd-hpa and dnsmasq with no esoterics due
    to the sheer amount of variables introduced.

    /var/lib/tftpboot/pxelinux.cfg/default:

    # not strictly necessary but makes the menu pretty
    menu hshift 13
    menu width 49
    menu margin 8
    
    menu title BackTrackBoot
    default vesamenu.c32
    display f.txt
    timeout 600
    
    label local
    menu label Local Harddisk
    localboot 0
    
    menu begin bt
    menu title BackTrack 5
    # ok here comes the real shit
    label backtrack5
    menu label BackTrack R1
    kernel bt5/vmlinuz
    append boot=casper netboot=nfs nfsroot=vulcano:/mnt/bt5 initrd=bt5/initrd.gz text splash vga=791 file=/cdrom/preseed/custom.seed --
    menu end
    

    you’ll need to copy to tftpboot/bt5 the initrd.gz and vmlinuz from the backtrack ISO /casper folder (which you can mount -o loop -t iso9660 bt5.iso /mnt/bt5

    the rest of the files you provide to the bootee over NFS

    /etc/exports:

    /mnt/bt5 10.10.3.0/24(rw,sync,no_subtree_check) 10.10.10.0/24(rw,sync,no_subtree_check)
    mount -t iso9660 -o loop BT5R1-GNOME-32.iso /mnt/bt5
    

    add a http server with kickstart / preseed files for an ever more powerful setup,
    in which case you replace the file= stanza in the append line with
    url=http://host/path/to/preseed

    more on preseeds… maybe later.

    Now restart all dependent services:

    /etc/init.d/nfs-kernel-server restart
    /etc/init.d/tftpd-hpa restart
    /etc/init.d/apache2 restart
    /etc/init.d/pxe restart
    

    debugging this setup usually requires tracing the process that is failing, so:
    - dhcp options tracing (dnsmasq verbose and tcpdump / wireshark)
    - verbose pxe
    - verbose foreground tftpd-hpa : in.tftpd -v -v -L /var/lib/tftpboot

    ip6 DNS wildcards considered harmful

    Friday, September 23rd, 2011

    I discovered something yesterday that might be of consequence:
    If you have ip6 connectivity the domain name resolver will prefer an ip6 wildcard domain over a ip4 A or CNAME record. This breaks things like ssh. You’d expect the resolver to choose the response that is most specific, the same way ip4 wildcards work, and not to blindly prefer ip6 wildcards.

    Consider the case of Mary, who’s been around and has lots of domains:

    hail.mary.com
    naked.mary.com
    see.mary.com
    

    and she’s also wildcarding all the other *.mary.com to her vanity host me.mary.com… you get the idea, it’s fairly typical. Those hosts only have ip4 connectivity. Now she adds a new address ip6.mary.com and puts a wildcard ip6 record *.mary.com, expecting that people accessing foo.mary.com on ip6 get the wildcard address – and they do! But she gets alot more than the doctor ordered, her ip6 clients will also get the ip6 wildcard address for all her other domains! hail.mary.com, naked.mary.com and see.mary.com will all land on ip6.mary.com instead of the ip4 A records. What happened here?
    Effectively, Mary’s ip6 wildcard broke all ip6 to ip4 connectivity for Mary’s existing subdomains!

    Yep, you can fix it on your machine, but this is a client problem and you can’t fix everybody else’s resolvers, so what you have to do is avoid ip6 wildcard domains ENTIRELY. Thanks a bunch.

    On a completly different node:

    “debug This option is recognized by pam_ldap but is presently ignored.”

    I mean wow. What did they do, write the whole module flawlessly on the first try? I wish.

    consolekit is evil

    Wednesday, December 1st, 2010

    … and hates me

    I should really tell you about the DLD seminar three weeks ago, or the PARANOIA security conference, or even just that Adobe should be considered harmful but things have been crazy and between this and electromagnetism I haven’t had the mind space. After the 6th of december, I promise I’l come back with pictures and relations and maybe even sounds (I have notes, don’t worry I’ll remember).

    On the other hand here’s a nasty hack to kill console-kit-daemon, which has a really nasty way of polluting the PID-space… and annoys me enough to warrant a public humiliation as well. What does it do, and why? Who cares what it does, it’s doing it poorly enough to catch attention to itself! So here’s how to kill it:

    root@wasp:/usr/sbin# dpkg -S console-kit-daemon
    consolekit: /usr/sbin/console-kit-daemon
    

    DON’T try to purge the package because that’s just one end of a really big ugly yarn of unneccessary dependency pain that I’d like to spare you…

    DON’T try to replace /usr/sbin/console-kit-daemon with your own stub… turns out dbus autostarts this “service”, and that approach will make dbus block your (ssh) session when you log in… not forever, but that’s even more annoying than the pid pollution.

    Instead, debian bug #544147 and #544483 clewed me in to the following hack:

    cp /usr/share/dbus-1/system-services/org.freedesktop.ConsoleKit.service \
      /usr/local/share/dbus-1/system-services/
    echo Exec=/bin/false >> /usr/local/share/dbus-1/system-services/org.freedesktop.ConsoleKit.service
    

    which is a two-liner, and would have been less ugly and easier to debug if it hadn’t been for the fine hubris of the freedesktop dudes…

    CPM 0.25 :: new packages

    Wednesday, September 15th, 2010

    sup peeps,
    your favorite password managment program, CPM, now has updated packages.
    What’s new in these packages is a working create-cpmdb. A fix for setting the SUID bit is also included, and that will allow CPM to store passwords securely in memory as well as on disk.

    Ubuntu and Debian users:
    Get cpm_0.25~beta-2debian3_amd64.deb directly from github.

    I have also taken the opportunity to update the documentation, which will allow you to roll your own CPM should you be running something other than debian.

    Quick start:

    me@mine:~# apt-get install libcdk5 libcrack2 libdotconf1.0 libgpg-error0 libgpgme11 libncursesw5 libxml2 libxml2-utils zlib1g
    me@mine:~# dpkg -i cpm_0.25~beta-2debian3_amd64.deb
    

    You need: a GPG key and 3 minutes of your time. Create the password database (only once):

    me@mine:~$ create-cpmdb
    

    Use your GPG key to encrypt the database. This puts a .cpmdb file in your home folder.

    Run CPM and add your passwords! Exit by hitting ESC to save the keys.

    me@mine:~$ cpm
    

    and you have a working CPM install.

    Furthermore, I have devised a way for many people to share the same passoword database through a revision control system. Take a look at CPM::revision control.

    backtrack to install a backtrack

    Thursday, September 9th, 2010

    BackTrack is your daddy.
    BackTrack accepts no compromises, yet it is all compromising.
    Because really, when is the last time you *didn’t* need those auditing tools? That penetration suite? Total privacy to break other people’s privacy? All that and a packet of crisps wrapped with razor sharp menus – it’s the kind of stuff you can only dream of on core. And I hear Fedora Core is the shitzitz now, adopting new [1] and exciting[2] features. Oh hey debian doesn’t have binary deltas for packages *yet* [3], but we’ve been talking about it way longer than those dudes have.

    Anecdtotally, I spilled a glass of water on my laptop the other day. Naturally, the glass went half empty in an instant: my poor lovely x41, I screamed. As it turns out the laptop casing made sure all the water was rather cleverly funneled into the x41′s only 1.8″ harddrive, which proceeded to go completely bananas (due presumably to rust, because clean water doesn’t conduct, right?). The data? I believe trusty old dd_rescue did rescue at least part of it, but I then misplaced the image file somewhere.

    The system?
    It was a thrifty, untrusted yet trusty Windows XP install that I’d been keeping on there on the mercy of actually booting every time since I bought the machine despite having been licked by more than its fair share of virii, malignant updates and accidental hard resets. Most of the programs I ran were portable[4] versions so all I lost were some documents and lots of music[5].

    The hardware?
    I disassembled and metricuously dried every little component, and in the end only the disk drive was bust. The 1.8″ IDE drive that is impossibly ridiculously expensive to replace (5$ per GB? What the foo? Shut up!). Still, I needed the laptop so I exploded booting from USB. Despite (misguided?) efforts I haven’t bloody well been able to boot windows off USB, so I bootstrapped BackTrack 3 instead and bob is your uncle.

    I mean really, I think I had that thing running like that for three months before I started missing stuff like apt. Didn’t really mind starting fresh every boot, I even invented a whole little schpiel for getting online as fast as possible, none of that Network Manager madness.
    Persistent settings are all right in BT3 but booting into RAM is a lot more fun. After the first 3 seconds of boot you can pull the USB plug, everything goes zippety fast and your footprint is nada. Only thing that can get your ass is a cold boot attack.

    BT3 is real cool and still a good recommend if you want to wardrive and do proper wifi phreaking due to the embedded injection drivers, but in the end I wanted new libs, a decent compiler and window dressing, and so I rolled BackTrack 4.

    Granted, kde sucks, but if I cared enough I’d switch to openbox or something awesome in like 4 minutes. These days all I need is a shell and a browser.

    For those of you fortunate enough to have a harddrive, BT4 ships with an install script to turn your system into a permanent BackTrack fixture. It’s based off Ubiquity, but dd’ing off the USB and onto your disk drive might be better if you’re interested in being able to boot your system into RAM, well I dunno because you want to do some advanced powersaving[6], or want to kill your system without worrying about unclean shutdowns, or want to maximise the life span of your solid-state device by nearly never writing to it.

    For my own part there was a happy ending on DealExtreme, as they ship IDE44 to CompactFlash interfaces that fit in the x41 1.8″ bay… which leads to a whole slew of unexplored possibilities thaaat (drum rolls) I will explore in the next installment of how to break your machine.

    BackTrack 4 R1 has released :-) [6]. Anyone know where I can score the BlackHat Edition?

    [1] http://fedoraproject.org/wiki/Releases/FeaturePresto
    [2] http://fedoraproject.org/wiki/Features/systemd
    [3] http://samba.anu.edu.au/rsync/rsync-and-debian/rsync-and-debian.html
    [4] http://portableapps.com/
    [5] http://drownedinsound.com/community/boards/music/4179554
    [6] http://kacper.blog.linpro.no/archives/13
    [7] http://www.backtrack-linux.org/

    pulse audio: an experiment in social engineering

    Tuesday, September 7th, 2010

    The title about sums up the sentiments on the topic in my department.
    What’s the use case for pulse audio?

    Apparently, pulse audio is:
    * configurationless consumer audio
    * something that sits between you and your sound
    * a replacement for ESD
    * necessary for normal printer(!) operation
    * cross-platform and works on windows
    * really really complex
    * the shit when you want less usability
    * the bomb when you want less security
    * not really competing with jack
    * really good at marketing itself
    * on by default in most current distros.

    The cure:
    apt-get remove –purge pulseaudio\*
    yum remove pulseaudio

    tune2fs and green disks

    Thursday, August 5th, 2010

    Hey folks,
    old news I’m sure, but if you get tempted into buying the new WD Caviar “Green Power” disks there is something you need to know about them: they fake 512-byte blocksizes while in reality having 4096-byte blocks! The move to 4K blocks is reasonable considering we just busted the 2 terabyte barrier, but the disk firmware is faking 512-byte blocks in the name of compatibility (read: so windows xp won’t shit itself).

    Unfortunately, running in bs512 mode makes the disk exactly 3x slower than it should be!
    The fix: line up your partitions at 4k boundries, so start partition one at block 64, 1024 or even 2048 (the win7 start block) not the default, 63, in most partitioning software. Start fdisk with the -u parameter and carefully specify the start block. In gparted you’ll have to unhook the “snap to cylinder boundries” checkbox, and then I suppose you could even move a partition to the right block, but expect this to take an inordinate amount of time!

    On a related note, fsck’ing an ext filesystem on boot is a drag, and fsck’ing 2TB file systems is a huge drag. Sure you should be running the fsck but it has a nasty tendency to happen on your workstation precisely when you can’t afford the extra 5 minute delay!

    I bump the default 10 mounts count to 0 (disabling mount count fscking) and auto-fsck my disks every 99 days, staggered so not all disks get checked on the same day. Do this with the tune2fs command:

    wasp:~# tune2fs -c 0 -i 99d /dev/sda1
    tune2fs 1.41.12 (17-May-2010)
    Setting maximal mount count to -1
    Setting interval between checks to 8553600 seconds
    

    out.

    PS I recently managed to achieve sustained throughputs of 110MB/s with these WD disks and properly aligned partitions:

    7516192768 bytes (7.5 GB) copied, 68.4392 s, 110 MB/s
    115+0 records in
    114+0 records out
    

    yes that’s disk-to-disk with ext4 and one large file, no fragmentation.

    PPS the defaults have nowadays changed to 120 days and 39 mounts, to which I say -1 mounts is better anyway!

    edit: Now that your files are aligned, you can specify a block size to mkfs as well, which might avoid unaligned fragments: mkfs.ext4 -b 4096 -L gigantor -O sparse_super /dev/sdb1

    CPM: Reliable multiuser password management

    Monday, August 2nd, 2010

    Sup all,
    summer is drawing to a close and vacation is definitely over, but I for one welcome the chance to think and act again. Some time ago our managed services department started complaining about various shoddy password management solutions. Truth be told we already had a good solution, CPM (“Console Password Management”) but the software had fallen into disrepair due to seldom and untidy updates from its author. A new maintainer was desired and a project to fix the software was decreed and the result fell into my lap so to speak.

    What sets CPM apart from other password management solutions is that it supports multiple users and goes to great lengths to keep your passwords secure while at the same time being very simple in its design: CPM locks its XML-formatted hierarchical password database in non-swappable private memory (so your passwords don’t get written in cleartext to disk while swapping), and encrypts the database with an arbitrary amount of GnuPG public keys.

    All this makes CPM quite nice for storing and sharing secrets in a nice curses-based searchable console interface.

    For the longest time I’ve been keeping the hundred-odd passwords I can’t remember on notepads and in random text files, thinking that surely I should start employing some sort of password management before I go crazy or my passwords leak. The congruence of my wishes with the scope of this project, so I picked up CPM and gave it a little love, and the result can be found at

    GitHub CPM with CPM packages for debian in the downloads section.

    CPM crash course

    Requirements: Gnu Privacy Guard, and a GPG keypair.

    First, install CPM:

    dpkg -i cpm_0.25~beta-2debian2_amd64.deb
    

    Then, create a password database, adding your key to the recipient list when prompted.

    create-cpmdb
    

    Then, use CPM from the console:

    cpm

    CPM should now ask you for you GPG key password and display an empty database.

    CPM is controlled with the arrow keys, Enter and some control keys.
    Hitting Control-H will bring you to the Help screen which explains the control keys.

    By default CPM organises your passwords in a structure of hosts that have several services which may have one or more users. Hosts, services, users and passwords are nodes in the tree and a node is added by hitting Control-A and given an appropriate name.

    For instance, if I were to add a password ch1ckens0up to user lolarun on the wiki service of host fragglepop.info, I would create the following node structure:

      host:fragglepop.info
          \-->service:wiki
                  \-->user:lolarun
                          \-->password:ch1ckens0up
    

    Of course there is no need to follow this anal layout, and you may even change the node structure by editing the template names in CPM by hitting Control-N or modifying the /etc/cpmrc config file.

    To have CPM generate a random password for you, hit Control-P.
    Your changes are not saved unless you hit Control-W or quit the program by hitting ESC enough times. Quitting through Control-C will not save the database.

    Future work includes pushing the package into Debian.

    What you don’t get (yet) is a GTK-based GUI, or a wrapper to pull the password database out of GIT and commit it again after modification nor integration with gpg-agent, probably (?) due to a bug in gpgme.

    Enjoy this lovely piece of software and leave a comment after testing it!