ABSTRACT: We examine the security requirements for creating a Deniable File System (DFS), and the efficacy with which the TrueCrypt disk-encryption software meets those requirements. We find that the Windows Vista operating system itself, Microsoft Word, and Google Desktop all compromise the deniability of a TrueCrypt DFS. While staged in the context of TrueCrypt, our research highlights several fundamental challenges to the creation and use of any DFS: even when the file system may be deniable in the pure, mathematical sense, we find that the environment surrounding that file system can undermine its deniability, as well as its contents. Finally, we suggest approaches for overcoming these challenges on modern operating systems like Windows.

There are several threat models against which a DFS could potentially be secure:

• One-Time Access. The attacker has a single snapshot of the disk image. An example would be when the secret police seize Alice’s computer.
• Intermittent Access. The attacker has several snapshots of the disk image, taken at different times. An example would be border guards who make a copy of Alice’s hard drive every time she enters or leaves the country.
• Regular Access. The attacker has many snapshots of the disk image, taken in short intervals. An example would be if the secret police break into Alice’s apartment every day when she is away, and make a copy of the disk each time.

We analyzed the most current version of TrueCrypt available at the writing of the paper, version 5.1a. We shared a draft of our paper with the TrueCrypt development team in May 2008. TrueCrypt version 6.0 was released in July 2008. We have not analyzed version 6.0, but observe that TrueCrypt v6.0 does take new steps to improve TrueCrypt’s deniability properties (e.g., via the creation of deniable operating systems, which we also recommend in Section 5). We suggest that the breadth of our results for TrueCrypt v5.1a highlight the challenges to creating deniable file systems. Given these potential challenges, we encourage the users not to blindly trust the deniability of such systems. Rather, we encourage further research evaluating the deniability of such systems, as well as research on new yet light-weight methods for improving deniability.

By the way, you may notice that I'm making fewer posts over the next month or so. I'll be busy studying for the GRE, wish me luck.

Enjoy.]]> Mon, 19 May 2008 02:36:31 +0000 nemesis nemesis-ip nemesis-rip nemesis-igmp nemesis-icmp nemesis-arp nemesis-tcp ettercap plugins ettercap BackTrack Beta 3 Man Pages http://securityratty.com/article/40186d92f5cac8291c8e4722ba6916a4 http://securityratty.com/article/40186d92f5cac8291c8e4722ba6916a4 aircrack-ng, airdecap-ng, airdriver-ng, aireplay-ng, airmon-ng, airodump-ng, airolib-ng, airpwn, airsev-ng, airsnort, airtun-ng, amap, ascii-xfr, atftp, bison, bsqldb, buddy-ng, cabextract, catdoc, catppt, datacopy, dcfldd, decrypt, defncopy, dhcpdump, dmitry, dos2unix, dupemap, easside-ng, etherape, flex, foremost, freebcp, gencases, getattach.pl, hexedit, httpcapture, ike-scan, ivstools, kstats, mac2unix, macchanger, magicrescue, magicsort, makeivs-ng, mboxgrep, minicom, nemesis-arp, nemesis-dns, nemesis-ethernet, nemesis-icmp, nemesis-igmp, nemesis-ip, nemesis-ospf, nemesis-rip, nemesis-tcp, nemesis-udp, nemesis, netcat, nmap, nmapfe, obexftp, obexftpd, p0f, packetforge-ng, psk-crack, rain, runscript, scrollkeeper-config, scrollkeeper-gen-seriesid, sipsak, socat, tcptraceroute, truecrypt, tsql, unicornscan, vomit, wesside-ng, wordview, xls2csv, xminicom, xnmap, gdbm, etter.conf, scrollkeeper.conf, sudoers, scrollkeeper,  80211debug, 80211stats, arpspoof, atftpd, athchans, athctrl, athdebug, athkey, athstats, ath_info, dnsspoof, dnstracer, dsniff, ettercap, ettercap_curses, ettercap_plugins, etterfilter, etterlog, filesnarf, fping, fragroute, fragtest, hping2, hping3, in.tftpd, macof, mailsnarf, msgsnarf, netdiscover, packit, scrollkeeper-preinstall, scrollkeeper-rebuilddb, scrollkeeper-update, sing, sshmitm, sshow, sudo, sudoedit, tcpick, tcpick_italian, tcpkill, tcpnice, tinyproxy, urlsnarf, visudo, webmitm, webspy, wlanconfig

Enjoy.

Enjoy.]]> Mon, 19 May 2008 02:36:31 +0000 nemesis nemesis-ip nemesis-rip nemesis-igmp nemesis-icmp nemesis-arp nemesis-tcp ettercap plugins ettercap BackTrack Beta 3 Man Pages http://securityratty.com/article/4bfe48e0614be15ff2d956bdb791a209 http://securityratty.com/article/4bfe48e0614be15ff2d956bdb791a209 Last month a US court ruled that border agents can search your laptop, or any other electronic device, when you're entering the country. They can take your computer and download its entire contents, or keep it for several days. Customs and Border Patrol has not published any rules regarding this practice, and I and others have written a letter to Congress urging it to investigate and regulate this practice.

But the US is not alone. British customs agents search laptops for pornography. And there are reports on the internet of this sort of thing happening at other borders, too. You might not like it, but it's a fact. So how do you protect yourself?

Encrypting your entire hard drive, something you should certainly do for security in case your computer is lost or stolen, won't work here. The border agent is likely to start this whole process with a "please type in your password". Of course you can refuse, but the agent can search you further, detain you longer, refuse you entry into the country and otherwise ruin your day.

You're going to have to hide your data. Set a portion of your hard drive to be encrypted with a different key - even if you also encrypt your entire hard drive - and keep your sensitive data there. Lots of programs allow you to do this. I use PGP Disk . TrueCrypt is also good, and free.

While customs agents might poke around on your laptop, they're unlikely to find the encrypted partition. (You can make the icon invisible, for some added protection.) And if they download the contents of your hard drive to examine later, you won't care.

Be sure to choose a strong encryption password. Details are too complicated for a quick tip, but basically anything easy to remember is easy to guess. (My advice is here.) Unfortunately, this isn't a perfect solution. Your computer might have left a copy of the password on the disk somewhere, and (as I also describe at the above link) smart forensic software will find it.

So your best defence is to clean up your laptop. A customs agent can't read what you don't have. You don't need five years' worth of email and client data. You don't need your old love letters and those photos (you know the ones I'm talking about). Delete everything you don't absolutely need. And use a secure file erasure program to do it. While you're at it, delete your browser's cookies, cache and browsing history. It's nobody's business what websites you've visited. And turn your computer off - don't just put it to sleep - before you go through customs; that deletes other things. Think of all this as the last thing to do before you stow your electronic devices for landing. Some companies now give their employees forensically clean laptops for travel, and have them download any sensitive data over a virtual private network once they've entered the country. They send any work back the same way, and delete everything again before crossing the border to go home. This is a good idea if you can do it.

If you can't, consider putting your sensitive data on a USB drive or even a camera memory card: even 16GB cards are reasonably priced these days. Encrypt it, of course, because it's easy to lose something that small. Slip it in your pocket, and it's likely to remain unnoticed even if the customs agent pokes through your laptop. If someone does discover it, you can try saying: "I don't know what's on there. My boss told me to give it to the head of the New York office." If you've chosen a strong encryption password, you won't care if he confiscates it.

Lastly, don't forget your phone and PDA. Customs agents can search those too: emails, your phone book, your calendar. Unfortunately, there's nothing you can do here except delete things.

I know this all sounds like work, and that it's easier to just ignore everything here and hope you don't get searched. Today, the odds are in your favour. But new forensic tools are making automatic searches easier and easier, and the recent US court ruling is likely to embolden other countries. It's better to be safe than sorry.

This essay originally appeared in The Guardian.

Some other advice here.