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War on General Purpose Computing auf Deutsch

Christian Wöhrl has produced a German translation of my 28C3 talk, The Coming War on General Purpose Computing. Thanks, Christian! Cory

Printer malware: print a malicious document, expose your whole LAN

One of the most mind-blowing presentations at this year's Chaos Communications Congress (28C3) was Ang Cui's Print Me If You Dare, in which he explained how he reverse-engineered the firmware-update process for HPs hundreds of millions of printers. Cui discovered that he could load arbitrary software into any printer by embedding it in a malicious document or by connecting to the printer online. As part of his presentation, he performed two demonstrations: in the first, he sent a document to a printer that contained a malicious version of the OS that caused it to copy the documents it printed and post them to an IP address on the Internet; in the second, he took over a remote printer with a malicious document, caused that printer to scan the LAN for vulnerable PCs, compromise a PC, and turn it into a proxy that gave him access through the firewall (I got shivers).

Cui gave HP a month to issue patches for the vulnerabilities he discovered, and HP now has new firmware available that fixes this (his initial disclosure was misreported in the press as making printers vulnerable to being overheated and turning into "flaming death bombs" -- he showed a lightly singed sheet of paper that represented the closest he could come to this claim). He urges anyone with an HP printer to apply the latest patch, because malware could be crafted to take over your printer and then falsely report that it has accepted the patch while discarding it.

Cui's tale of reverse-engineering is a fantastic look at the craft and practice of exploring security vulnerabilities. The cases he imagined for getting malware into printers were very good: send a resume to HR, wait for them to print it, take over the network and pwn the company.

Cui believes that these vulnerabilities are likely present on non-HP printers (a related talk on PostScript hacking lent support to his belief) and his main area of research is a generalized anti-malware solution for all embedded systems, including printers and routers.

Just in case this has scared the hell out of you (as it did me), be assured that there are many lulz to be had, especially when Cui described his interactions with HP, who actually had a firmware flag called "super-secret bypass of crypto-key enabled."

Print Me If You Dare

State of Adversarial Stylometry: can you change your prose-style?

Today at the Chaos Computer Congress in Berlin (28C3), Sadia Afroz and Michael Brennan presented a talk called "Deceiving Authorship Detection," about research from Drexel College on "Adversarial Stylometry," the practice of identifying the authors of texts who don't want to be identified, and the process of evading detection. Stylometry has made great and well-publicized advances in recent years (and it made the news with scandals like "Gay Girl in Damascus"), but typically this has been against authors who have not taken active, computer-assisted countermeasures at disguising their distinctive "voice" in prose.

As part of the presentation, the Drexel Team released Anonymouth, a free/open tool that partially automates the process of evading authorship detection. The tool is still a rough alpha, and it requires human intervention to oversee the texts it produces, but it is still an exciting move in adversarial stylometry tools. Accompanying the release are large corpuses of test data of deceptive and non-deceptive texts.

Stylometry has been cited by knowledgeable critics as proof of the pointlessness of the Nym Wars: why argue for the right to be anonymous or pseudonymous on Google Plus or Facebook when stylometry will de-anonymize you anyway? I've been suspect of these critiques because they assume that only de-anonymizers will have access to computer-assisted tools, but as Anonymouth shows, there are many opportunities to use automation tools to improve anonymity.

Stylometry matters in many ways: its state of the art changes the balance of power between trolls and moderators, between dissidents and dictators, between employers and whistleblowers, between astroturfers and commenters, and between spammers and filters.

During the Q&A, a questioner asked whether Anonymouth's methods could be used by, say, fanfic authors to make their writing style match the author whose universe they're dabbling in; the researchers thought this would be so. I instantly wondered if avid fans might make a JK-Rowlingifier that could be used by dissidents to anonymize their speech, homogenizing it to pitch-perfect Potterian English so that stylometry fails. And of course, this makes me wonder whether stylometry could be used to falsely identify a block of prose with a third party (making a terrorist rant stylometrically match an innocent's prose-style) -- the researchers doubt this, and suggest that when deception is a possibility, prose-style shouldn't be considered as identifying evidence.

As an aside, the Anonymouth team is part of a lab at Drexel seeking grad-students and postdocs.

Privacy, Security and Automation Lab