Entries Tagged "browsers"
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A couple of weeks ago Wired reported the discovery of a new, undeletable, web cookie:
Researchers at U.C. Berkeley have discovered that some of the net’s most popular sites are using a tracking service that can’t be evaded — even when users block cookies, turn off storage in Flash, or use browsers’ “incognito” functions.
The Wired article was very short on specifics, so I waited until one of the researchers — Ashkan Soltani — wrote up more details. He finally did, in a quite technical essay:
The German Federal Criminal Police (the “Bundeskriminalamt” or BKA for short) recently warned consumers about a new Windows malware strain that waits until the victim logs in to his bank account. The malware then presents the customer with a message stating that a credit has been made to his account by mistake, and that the account has been frozen until the errant payment is transferred back.
When the unwitting user views his account balance, the malware modifies the amounts displayed in his browser; it appears that he has recently received a large transfer into his account. The victim is told to immediately make a transfer to return the funds and unlock his account. The malicious software presents an already filled-in online transfer form with the account and routing numbers for a bank account the attacker controls.
ShareMeNot is a Firefox add-on for preventing tracking from third-party buttons (like the Facebook “Like” button or the Google “+1” button) until the user actually chooses to interact with them. That is, ShareMeNot doesn’t disable/remove these buttons completely. Rather, it allows them to render on the page, but prevents the cookies from being sent until the user actually clicks on them, at which point ShareMeNot releases the cookies and the user gets the desired behavior (i.e., they can Like or +1 the page).
The U.S. Federal Trade Commission released its privacy report: “Protecting Consumer Privacy in an Era of Rapid Change.”
From the press release:
One method of simplified choice the FTC staff recommends is a “Do Not Track” mechanism governing the collection of information about consumer’s Internet activity to deliver targeted advertisements and for other purposes. Consumers and industry both support increased transparency and choice for this largely invisible practice. The Commission recommends a simple, easy to use choice mechanism for consumers to opt out of the collection of information about their Internet behavior for targeted ads. The most practical method would probably involve the placement of a persistent setting, similar to a cookie, on the consumer’s browser signaling the consumer’s choices about being tracked and receiving targeted ads.
Firesheep is a new Firefox plugin that makes it easy for you to hijack other people’s social network connections. Basically, Facebook authenticates clients with cookies. If someone is using a public WiFi connection, the cookies are sniffable. Firesheep uses wincap to capture and display the authentication information for accounts it sees, allowing you to hijack the connection.
Slides from the Toorcon talk.
Protect yourself by forcing the authentication to happen over TLS. Or stop logging in to Facebook from public networks.
EDITED TO ADD (10/27): To protect against this attack, you have to encrypt the entire session — not just the initial authentication.
EDITED TO ADD (11/17): Blacksheep detects Firesheep.
evercookie accomplishes this by storing the cookie data in several types of storage mechanisms that are available on the local browser. Additionally, if evercookie has found the user has removed any of the types of cookies in question, it recreates them using each mechanism available.
Specifically, when creating a new cookie, it uses the following storage mechanisms when available:
- Standard HTTP Cookies
- Local Shared Objects (Flash Cookies)
- Storing cookies in RGB values of auto-generated, force-cached PNGs using HTML5 Canvas tag to read pixels (cookies) back out
- Storing cookies in Web History (seriously. see FAQ)
- HTML5 Session Storage
- HTML5 Local Storage
- HTML5 Global Storage
- HTML5 Database Storage via SQLite
And the arms race continues….
EDITED TO ADD (9/24): WARNING — When you visit this site, it stores an evercookie on your machine.
Who are these certificate authorities? At the beginning of Web history, there were only a handful of companies, like Verisign, Equifax, and Thawte, that made near-monopoly profits from being the only providers trusted by Internet Explorer or Netscape Navigator. But over time, browsers have trusted more and more organizations to verify Web sites. Safari and Firefox now trust more than 60 separate certificate authorities by default. Microsoft’s software trusts more than 100 private and government institutions.
Disturbingly, some of these trusted certificate authorities have decided to delegate their powers to yet more organizations, which aren’t tracked or audited by browser companies. By scouring the Net for certificates, security researchers have uncovered more than 600 groups who, through such delegation, are now also automatically trusted by most browsers, including the Department of Homeland Security, Google, and Ford Motorsand a UAE mobile phone company called Etisalat.
In 2005, a company called CyberTrust—which has since been purchased by Verizon—gave Etisalat, the government-connected mobile company in the UAE, the right to verify that a site is valid. Here’s why this is trouble: Since browsers now automatically trust Etisalat to confirm a site’s identity, the company has the potential ability to fake a secure connection to any site Etisalat subscribers might visit using a man-in-the-middle scheme.
EDITED TO ADD (9/14): EFF has gotten involved.
- We analyzed the results from over a quarter of a million people who ran our tests in the last few months, and found that we can detect browsing histories for over 76% of them. All major browsers allow their users’ history to be detected, but it seems that users of the more modern browsers such as Safari and Chrome are more affected; we detected visited sites for 82% of Safari users and 94% of Chrome users.
- While our tests were quite limited, for our test of 5000 most popular websites, we detected an average of 63 visited locations (13 sites and 50 subpages on those sites); the medians were 8 and 17 respectively.
- Almost 10% of our visitors had over 30 visited sites and 120 subpages detected — heavy Internet users who don’t protect themselves are more affected than others.
- The ability to detect visitors’ browsing history requires just a few lines of code. Armed with a list of websites to check for, a malicious webmaster can scan over 25 thousand links per second (1.5 million links per minute) in almost every recent browser.
- Most websites and pages you view in your browser can be detected as long as they are kept in your history. Almost every address that was in your browser’s address bar can be detected (this includes most pages, including those retrieved using https and some forms with potentialy private information such as your zipcode or search query). Pages won’t be detected when they expire from your history (usually after a month or two), or if you manually clear it.
For now, the only way to fix the issue is to constantly clear browsing history or use private browsing modes. The first browser to prevent this trick in a default installation (Firefox 4.0) is supposed to come out in October.
Here’s a link to the paper.
How unique is your browser? Can you be tracked simply by its characteristics? The EFF is trying to find out. Their site Panopticlick will measure the characteristics of your browser setup and tell you how unique it is.
I just ran the test on myself, and my browser is unique amongst the 120,000 browsers tested so far. It’s my browser plugin details; no one else has the exact configuration I do. My list of system fonts is almost unique; only one other person has the exact configuration I do. (This seems odd to me, I have a week old Sony laptop running Windows 7, and I haven’t done anything with the fonts.)
EDITED TO ADD (1/29): There’s a lot in the comments leading me to question the accuracy of this test. I’ll post more when I know more.
EDITED TO ADD (2/12): Comments from one of the project developers.
Sidebar photo of Bruce Schneier by Joe MacInnis.