Entries Tagged "phishing"

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Second SHB Workshop Liveblogging (4)

Session three was titled “Usability.” (For the record, the Stata Center is one ugly building.)

Andrew Patrick, NRC Canada until he was laid off four days ago (suggested reading: Fingerprint Concerns: Performance, Usability, and Acceptance of Fingerprint Biometric Systems), talked about biometric systems and human behavior. Biometrics are used everywhere: for gym membership, at Disneyworld, at international borders. The government of Canada is evaluating using iris recognition at a distance for events like the 2010 Olympics. There are two different usability issues: with respect to the end user, and with respect to the authenticator. People’s acceptance of biometrics is very much dependent on the context. And of course, biometrics are not secret. Patrick suggested that to defend ourselves against this proliferation of using biometrics for authentication, the individual should publish them. The rationale is that we’re publishing them anyway, so we might as well do it knowingly.

Luke Church, Cambridge University (suggested reading: SHB Position Paper; Usability and the Common Criteria), talked about what he called “user-centered design.” There’s a economy of usability: “in order to make some things easier, we have to make some things harder”—so it makes sense to make the commonly done things easier at the expense of the rarely done things. This has a lot of parallels with security. The result is “appliancisation” (with a prize for anyone who come up with a better name): the culmination of security behaviors and what the system can do embedded in a series of user choices. Basically, giving users meaningful control over their security. Luke discussed several benefits and problems with the approach.

Diana Smetters, Palo Alto Research Center (suggested reading: Breaking out of the browser to defend against phishing attacks; Building secure mashups; Ad-hoc guesting: when exceptions are the rule), started with these premises: you can teach users, but you can’t teach them very much, so you’d better carefully design systems so that you 1) minimize what they have to learn, 2) make it easier for them to learn it, and 3) maximize the benefit from what they learn. Too often, security is at odds with getting the job done. “As long as configuration errors (false alarms) are common, any technology that requires users to observe security indicators and react to them will fail as attacks can simply masquerade as errors, and users will rationally ignore them.” She recommends meeting the user halfway by building new security models that actually fit the users’ needs. (For example: Phishing is a mismatch problem, between what’s in the user’s head and where the URL is actually going. SSL doesn’t work, but how should websites authenticate themselves to users? Her solution is protected links: a set of secure bookmarks in protected browsers. She went on to describe a prototype and tests run with user subjects.

Jon Callas, PGP Corporation (suggested reading: Improving Message Security with a Self-Assembling PKI), used the metaphor of the “security cliff”: you have to keep climbing until you get to the top and that’s hard, so it’s easier to just stay at the bottom. He wants more of a “security ramp,” so people can reasonably stop somewhere in the middle. His idea is to have a few policies—e-mail encryption, rules about USB drives—and enforce them. This works well in organizations, where IT has dictatorial control over user configuration. If we can’t teach users much, we need to enforce policies on users.

Rob Reeder, Microsoft (suggested reading: Expanding Grids for Visualizing and Authoring Computer Security Policies), presented a possible solution to the secret questions problem: social authentication. The idea is to use people you know (trustees) to authenticate who you are, and have them attest to the fact that you lost your password. He went on to describe how the protocol works, as well as several potential attacks against the protocol and defenses, and experiments that tested the protocol. In the question session he talked about people designating themselves as trustees, and how that isn’t really a problem.

Lorrie Cranor, Carnegie Mellon University (suggested reading: A Framework for Reasoning about the Human in the Loop; Timing Is Everything? The Effects of Timing and Placement of Online Privacy Indicators; School of Phish: A Real-Word Evaluation of Anti-Phishing Training; You’ve Been Warned: An Empirical Study of the Effectiveness of Web Browser Phishing Warnings), talked about security warnings. The best option is to fix the hazard; the second best is to guard against it—but far too often we just warn people about it. But since hazards are generally not very hazardous, most people just ignore them. “Often, software asks the user and provides little or no information to help user make this decision.” Better is to use some sort of automated analysis to assist the user in responding to warnings. For websites, for example, the system should block sites with a high probability of danger, not bother users if there is a low probably of danger, and help the user make the decision in the grey area. She went on to describe a prototype and user studies done with the prototype; her paper will be presented at USENIX Security in August.

Much of the discussion centered on how bad the problem really is, and how much security is good enough. The group also talked about economic incentives companies have to either fix or ignore security problems, and whether market approaches (or, as Jean Camp called it, “the happy Libertarian market pony”) are sufficient. Some companies have incentives to convince users to do the wrong thing, or at the very least to do nothing. For example, social networking sites are more valuable if people share their information widely.

Further discussion was about whitelisting, and whether it worked or not. There’s the problem of the bad guys getting on the whitelist, and the risk that organizations like the RIAA will use the whitelist to enforce copyright, or that large banks will use the whitelist as a tool to block smaller start-up banks. Another problem is that the user might not understand what a whitelist signifies.

Dave Clark from the audience: “It’s not hard to put a seat belt on, and if you need a lesson, take a plane.”

Kind of a one-note session. We definitely need to invite more psych people.

Adam Shostack’s liveblogging is here. Ross Anderson’s liveblogging is in his blog post’s comments. Matt Blaze’s audio is here.

Posted on June 11, 2009 at 2:56 PM • View Comments

Second SHB Workshop Liveblogging (3)

The second session was about fraud. (These session subjects are only general. We tried to stick related people together, but there was the occasional oddball—and scheduling constraint—to deal with.)

Julie Downs, Carnegie Mellon University (suggested reading: Behavioral Response to Phishing Risk; Parents’ vaccination comprehension and decisions; The Psychology of Food Consumption), is a psychologist who studies how people make decisions, and talked about phishing. To determine how people respond to phishing attempts—what e-mails they open and when they click on links—she watched as people interacted with their e-mail. She found that most people’s strategies to deal with phishing attacks might have been effective 5-10 years ago, but are no longer sufficient now that phishers have adapted. She also found that educating people about phishing didn’t make them more effective at spotting phishing attempts, but made them more likely to be afraid of doing anything on line. She found this same overreaction among people who were recently the victims of phishing attacks, but again people were no better separating real e-mail from phishing attempts. What does make a difference is contextual understanding: how to parse a URL, how and why the scams happen, what SSL does and doesn’t do.

Jean Camp, Indiana University (suggested reading: Experimental Evaluation of Expert and Non-expert Computer Users’ Mental Models of Security Risks), studies people taking risks online. Four points: 1) “people create mental models from internal narratives about risk,” 2) “risk mitigating action is taken only if the risk is perceived as relevant,” 3) “contextualizing risk can show risks as relevant,” and 4) “narrative can increase desire and capacity to use security tools.” Stories matter: “people are willing to wash out their cat food cans and sweep up their sweet gum balls to be a good neighbor, but allow their computers to join zombie networks” because there’s a good story in the former and none in the latter. She presented two experiments to demonstrate this. One was a video experiment watching business majors try to install PGP. No one was successful: there was no narrative, and the mixed metaphor of physical and cryptographic “key” confused people.

Matt Blaze, University of Pennsylvania (his blog), talked about electronic voting machines and fraud. He related this anecdote about actual electronic voting machine vote fraud in Kentucky. In the question session, he speculated about the difficulty of having a security model that would have captured the problem, and how to know whether that model was complete enough.

Jeffrey Friedberg, Microsoft (suggested reading: Internet Fraud Battlefield; End to End Trust and the Trust User Experience; Testimony on “spyware”), discussed research at Microsoft around the Trust User Experience (TUX). He talked about the difficulty of verifying SSL certificates. Then he talked about how Microsoft added a “green bar” to signify trusted sites, and how people who learned to trust the green bar were fooled by “picture in picture attacks”: where a hostile site embedded a green-bar browser window in its page. Most people don’t understand that the information inside the browser window is arbitrary, but that the stuff around it is not. The user interface, user experience, mental models all matter. Designing and evaluating TUX is hard. From the questions: training doesn’t help much, because given a plausible story, people will do things counter to their training.

Stuart Schechter, Microsoft, presented this research on secret questions. Basically, secret questions don’t work. They’re easily guessable based on the most common answers; friends and relatives of people can easily predict unique answers; and people forget their answers. Even worse, the more memorable the question/answers are, the easier they are to guess. Having people write their own questions is no better: “What’s my blood type?” “How tall am I?”

Tyler Moore, Harvard University (suggested reading: The Consequences of Non-Cooperation in the Fight against Phishing; Information Security Economics—and Beyond), discussed his empirical studies on online crime and defense. Fraudsters are good at duping users, but they’re also effective at exploiting failures among IT professionals to perpetuate the infrastructure necessary to carry out these exploits on a large scale (hosting fake web pages, sending spam, laundering the profits via money mules, and so on). There is widespread refusal among the defenders to cooperate with each other, and attackers exploit these limitations. We are better at removing phishing websites than we are at defending against the money mules. Defenders tend to fix immediate problems, but not underlying problems.

In the discussion phase, there was a lot of talk about the relationships between websites, like banks, and users—and how that affects security for both good and bad. Jean Camp doesn’t want a relationship with her bank, because that unduly invests her in the bank. (Someone from the audience pointed out that, as a U.S. taxpayer, she is already invested in her bank.) Angela Sasse said that the correct metaphor is “rules of engagement,” rather than relationships.

Adam Shostack’s liveblogging. Ross Anderson’s liveblogging is in his blog post’s comments.

Matt Blaze is taping the sessions—except for the couple of presenters who would rather not be taped—I’ll post his links as soon as the files are online.

EDITED TO ADD (6/11): Audio of the session is here.

Posted on June 11, 2009 at 11:42 AM • View Comments

NSA Patent on Network Tampering Detection

The NSA has patented a technique to detect network tampering:

The NSA’s software does this by measuring the amount of time the network takes to send different types of data from one computer to another and raising a red flag if something takes too long, according to the patent filing.

Other researchers have looked into this problem in the past and proposed a technique called distance bounding, but the NSA patent takes a different tack, comparing different types of data travelling across the network. “The neat thing about this particular patent is that they look at the differences between the network layers,” said Tadayoshi Kohno, an assistant professor of computer science at the University of Washington.

The technique could be used for purposes such as detecting a fake phishing Web site that was intercepting data between users and their legitimate banking sites, he said. “This whole problem space has a lot of potential, [although] I don’t know if this is going to be the final solution that people end up using.”

Posted on December 30, 2008 at 12:07 PM • View Comments

News from the Rock Phish Gang

Definitely interesting:

Based in Europe, the Rock Phish group is a criminal collective that has been targeting banks and other financial institutions since 2004. According to RSA, they are responsible for half of the worldwide phishing attacks and have siphoned tens of millions of dollars from individuals’ bank accounts. The group got its name from a now discontinued quirk in which the phishers used directory paths that contained the word “rock.”

The first sign the group was expanding operations came in April, when it introduced a trojan known alternately as Zeus or WSNPOEM, which steals sensitive financial information in transit from a victim’s machine to a bank. Shortly afterward, the gang added more crimeware, including a custom-made botnet client that was spread, among other means, using the Neosploit infection kit.

[…]

Soon, additional signs appeared pointing to a partnership between Rock Phishers and Asprox. Most notably, the command and control server for the custom Rock Phish crimeware had exactly the same directory structure of many of the Asprox servers, leading RSA researchers to believe Rock Phish and Asprox attacks were using at least one common server. (Researchers from Damballa were able to confirm this finding after observing malware samples from each of the respective botnets establish HTTP proxy server connections to a common set of destination IPs.)

Posted on September 10, 2008 at 7:47 AM • View Comments

Man-in-the-Middle Attacks

Last week’s dramatic rescue of 15 hostages held by the guerrilla organization FARC was the result of months of intricate deception on the part of the Colombian government. At the center was a classic man-in-the-middle attack.

In a man-in-the-middle attack, the attacker inserts himself between two communicating parties. Both believe they’re talking to each other, and the attacker can delete or modify the communications at will.

The Wall Street Journal reported how this gambit played out in Colombia:

“The plan had a chance of working because, for months, in an operation one army officer likened to a ‘broken telephone,’ military intelligence had been able to convince Ms. Betancourt’s captor, Gerardo Aguilar, a guerrilla known as ‘Cesar,’ that he was communicating with his top bosses in the guerrillas’ seven-man secretariat. Army intelligence convinced top guerrilla leaders that they were talking to Cesar. In reality, both were talking to army intelligence.”

This ploy worked because Cesar and his guerrilla bosses didn’t know one another well. They didn’t recognize one anothers’ voices, and didn’t have a friendship or shared history that could have tipped them off about the ruse. Man-in-the-middle is defeated by context, and the FARC guerrillas didn’t have any.

And that’s why man-in-the-middle, abbreviated MITM in the computer-security community, is such a problem online: Internet communication is often stripped of any context. There’s no way to recognize someone’s face. There’s no way to recognize someone’s voice. When you receive an e-mail purporting to come from a person or organization, you have no idea who actually sent it. When you visit a website, you have no idea if you’re really visiting that website. We all like to pretend that we know who we’re communicating with—and for the most part, of course, there isn’t any attacker inserting himself into our communications—but in reality, we don’t. And there are lots of hacker tools that exploit this unjustified trust, and implement MITM attacks.

Even with context, it’s still possible for MITM to fool both sides—because electronic communications are often intermittent. Imagine that one of the FARC guerrillas became suspicious about who he was talking to. So he asks a question about their shared history as a test: “What did we have for dinner that time last year?” or something like that. On the telephone, the attacker wouldn’t be able to answer quickly, so his ruse would be discovered. But e-mail conversation isn’t synchronous. The attacker could simply pass that question through to the other end of the communications, and when he got the answer back, he would be able to reply.

This is the way MITM attacks work against web-based financial systems. A bank demands authentication from the user: a password, a one-time code from a token or whatever. The attacker sitting in the middle receives the request from the bank and passes it to the user. The user responds to the attacker, who passes that response to the bank. Now the bank assumes it is talking to the legitimate user, and the attacker is free to send transactions directly to the bank. This kind of attack completely bypasses any two-factor authentication mechanisms, and is becoming a more popular identity-theft tactic.

There are cryptographic solutions to MITM attacks, and there are secure web protocols that implement them. Many of them require shared secrets, though, making them useful only in situations where people already know and trust one another.

The NSA-designed STU-III and STE secure telephones solve the MITM problem by embedding the identity of each phone together with its key. (The NSA creates all keys and is trusted by everyone, so this works.) When two phones talk to each other securely, they exchange keys and display the other phone’s identity on a screen. Because the phone is in a secure location, the user now knows who he is talking to, and if the phone displays another organization—as it would if there were a MITM attack in progress—he should hang up.

Zfone, a secure VoIP system, protects against MITM attacks with a short authentication string. After two Zfone terminals exchange keys, both computers display a four-character string. The users are supposed to manually verify that both strings are the same—”my screen says 5C19; what does yours say?”—to ensure that the phones are communicating directly with each other and not with an MITM. The AT&T TSD-3600 worked similarly.

This sort of protection is embedded in SSL, although no one uses it. As it is normally used, SSL provides an encrypted communications link to whoever is at the other end: bank and phishing site alike. And the better phishing sites create valid SSL connections, so as to more effectively fool users. But if the user wanted to, he could manually check the SSL certificate to see if it was issued to “National Bank of Trustworthiness” or “Two Guys With a Computer in Nigeria.”

No one does, though, because you have to both remember and be willing to do the work. (The browsers could make this easier if they wanted to, but they don’t seem to want to.) In the real world, you can easily tell a branch of your bank from a money changer on a street corner. But on the internet, a phishing site can be easily made to look like your bank’s legitimate website. Any method of telling the two apart takes work. And that’s the first step to fooling you with a MITM attack.

Man-in-the-middle isn’t new, and it doesn’t have to be technological. But the internet makes the attacks easier and more powerful, and that’s not going to change anytime soon.

This essay originally appeared on Wired.com.

Posted on July 15, 2008 at 6:47 AM • View Comments

Hacking ISP Error Pages

This is a big deal:

At issue is a growing trend in which ISPs subvert the Domain Name System, or DNS, which translates website names into numeric addresses.

When users visit a website like Wired.com, the DNS system maps the domain name into an IP address such as 72.246.49.48. But if a particular site does not exist, the DNS server tells the browser that there’s no such listing and a simple error message should be displayed.

But starting in August 2006, Earthlink instead intercepts that Non-Existent Domain (NXDOMAIN) response and sends the IP address of ad-partner Barefruit’s server as the answer. When the browser visits that page, the user sees a list of suggestions for what site the user might have actually wanted, along with a search box and Yahoo ads.

The rub comes when a user is asking for a nonexistent subdomain of a real website, such as http://webmale.google.com, where the subdomain webmale doesn’t exist (unlike, say, mail in mail.google.com). In this case, the Earthlink/Barefruit ads appear in the browser, while the title bar suggests that it’s the official Google site.

As a result, all those subdomains are only as secure as Barefruit’s servers, which turned out to be not very secure at all. Barefruit neglected basic web programming techniques, making its servers vulnerable to a malicious JavaScript attack. That meant hackers could have crafted special links to unused subdomains of legitimate websites that, when visited, would serve any content the attacker wanted.

The hacker could, for example, send spam e-mails to Earthlink subscribers with a link to a webpage on money.paypal.com. Visiting that link would take the victim to the hacker’s site, and it would look as though they were on a real PayPal page.

Kaminsky demonstrated the vulnerability by finding a way to insert a YouTube video from 80s pop star Rick Astley into Facebook and PayPal domains. But a black hat hacker could instead embed a password-stealing Trojan. The attack might also allow hackers to pretend to be a logged-in user, or to send e-mails and add friends to a Facebook account.

Earthlink isn’t alone in substituting ad pages for error messages, according to Kaminsky, who has seen similar behavior from other major ISPs including Verizon, Time Warner, Comcast and Qwest.

Another article.

Posted on April 24, 2008 at 6:43 AM • View Comments

Targeted Phishing from Salesforce.com Leak

From Slashdot:

Salesforce.com has finally acknowledged what security experts have suspected for weeks: that a Salesforce.com employee had his company credentials stolen
in a phishing scam, and criminals have been using names and e-mail addresses from Salesforce’s customer list to conduct other highly targeted phishing attacks, including the recent round of fake e-mails apparently from the Federal Trade Commission.” In such hightly targeted attacks, the AV companies are at a loss—they have little chance of quickly developing signatures for threats that only reach a few thousand victims.

Posted on November 8, 2007 at 7:33 AM • View Comments

Understanding the Black Market in Internet Crime

Here’s a interesting paper from Carnegie Mellon University: “An Inquiry into the Nature and Causes of the Wealth of Internet Miscreants.”

The paper focuses on the large illicit market that specializes in the commoditization of activities in support of Internet-based crime. The main goal of the paper was to understand and measure how these markets function, and discuss the incentives of the various market entities. Using a dataset collected over seven months and comprising over 13 million messages, they were able to categorize the market’s participants, the goods and services advertised, and the asking prices for selected interesting goods.

Really cool stuff.

Unfortunately, the data is extremely noisy and so far the authors have no way to cross-validate it, so it is difficult to make any strong conclusions.

The press focused on just one thing: a discussion of general ways to disrupt the market. Contrary to the claims of the article, the authors have not built any tools to disrupt the markets.

Related blog posts: Gozi and Storm.

Posted on October 29, 2007 at 2:23 PM • View Comments

Security Risks of Online Political Contributing

Security researcher Christopher Soghoian gave a presentation this month warning of the potential phishing risk caused by online political donation sites. The Threat Level blog reported:

The presidential campaigns’ tactic of relying on impulsive giving spurred by controversial news events and hyped-up deadlines, combined with a number of other factors such as inconsistent Web addresses and a muddle of payment mechanisms creates a conducive environment for fraud, says Soghoian.

“Basically, the problem here is that banks are doing their best to promote safe online behavior, but the political campaigns are taking advantage of the exact opposite,” he says. “They send out one million e-mails to people designed to encourage impulsive behavior.”

He characterizes the current state of security of the presidential campaigns’ online payment systems as a “mess.”

“It’s a disaster waiting to happen,” he says.

Fraudsters could easily send out e-mails and establish Web sites that mimic the official campaigns’ sites and similarly send out such e-mails that would encourage people to “donate” money without checking for the authenticity of the site.

He has a point, but it’s not new to online contributions. Fake charities and political organizations have long been problems. When you get a solicitation in the mail for “Concerned Citizens for a More Perfect Country”—insert whatever personal definition you have for “more perfect” and “country”—you don’t know if the money is going to your cause or into someone’s pocket. When you give money on the street to someone soliciting contributions for this cause or that one, you have no idea what will happen to the money at the end of the day.

In the end, contributing money requires trust. While the Internet certainly makes frauds like this easier—anyone can set up a webpage that accepts PayPal and send out a zillion e-mails—it’s nothing new.

Posted on October 16, 2007 at 12:20 PM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.