Entries Tagged "impersonation"

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New SHA-1 Attack

There’s a new, practical, collision attack against SHA-1:

In this paper, we report the first practical implementation of this attack, and its impact on real-world security with a PGP/GnuPG impersonation attack. We managed to significantly reduce the complexity of collisions attack against SHA-1: on an Nvidia GTX 970, identical-prefix collisions can now be computed with a complexity of 261.2rather than264.7, and chosen-prefix collisions with a complexity of263.4rather than267.1. When renting cheap GPUs, this translates to a cost of 11k US$ for a collision,and 45k US$ for a chosen-prefix collision, within the means of academic researchers.Our actual attack required two months of computations using 900 Nvidia GTX 1060GPUs (we paid 75k US$ because GPU prices were higher, and we wasted some time preparing the attack).

It has practical applications:

We chose the PGP/GnuPG Web of Trust as demonstration of our chosen-prefix collision attack against SHA-1. The Web of Trust is a trust model used for PGP that relies on users signing each other’s identity certificate, instead of using a central PKI. For compatibility reasons the legacy branch of GnuPG (version 1.4) still uses SHA-1 by default for identity certification.

Using our SHA-1 chosen-prefix collision, we have created two PGP keys with different UserIDs and colliding certificates: key B is a legitimate key for Bob (to be signed by the Web of Trust), but the signature can be transferred to key A which is a forged key with Alice’s ID. The signature will still be valid because of the collision, but Bob controls key A with the name of Alice, and signed by a third party. Therefore, he can impersonate Alice and sign any document in her name.

From a news article:

The new attack is significant. While SHA1 has been slowly phased out over the past five years, it remains far from being fully deprecated. It’s still the default hash function for certifying PGP keys in the legacy 1.4 version branch of GnuPG, the open-source successor to PGP application for encrypting email and files. Those SHA1-generated signatures were accepted by the modern GnuPG branch until recently, and were only rejected after the researchers behind the new collision privately reported their results.

Git, the world’s most widely used system for managing software development among multiple people, still relies on SHA1 to ensure data integrity. And many non-Web applications that rely on HTTPS encryption still accept SHA1 certificates. SHA1 is also still allowed for in-protocol signatures in the Transport Layer Security and Secure Shell protocols.

Posted on January 8, 2020 at 9:38 AM • View Comments

Identity Theft on the Job Market

Identity theft is getting more subtle: “My job application was withdrawn by someone pretending to be me“:

When Mr Fearn applied for a job at the company he didn’t hear back.

He said the recruitment team said they’d get back to him by Friday, but they never did.

At first, he assumed he was unsuccessful, but after emailing his contact there, it turned out someone had created a Gmail account in his name and asked the company to withdraw his application.

Mr Fearn said the talent assistant told him they were confused because he had apparently emailed them to withdraw his application on Wednesday.

“They forwarded the email, which was sent from an account using my name.”

He said he felt “really shocked and violated” to find out that someone had created an email account in his name just to tarnish his chances of getting a role.

This is about as low-tech as it gets. It’s trivially simple for me to open a new Gmail account using a random first and last name. But because people innately trust email, it works.

Posted on July 18, 2019 at 8:21 AM • View Comments

Attacking Soldiers on Social Media

A research group at NATO’s Strategic Communications Center of Excellence catfished soldiers involved in an European military exercise—we don’t know what country they were from—to demonstrate the power of the attack technique.

Over four weeks, the researchers developed fake pages and closed groups on Facebook that looked like they were associated with the military exercise, as well as profiles impersonating service members both real and imagined.

To recruit soldiers to the pages, they used targeted Facebook advertising. Those pages then promoted the closed groups the researchers had created. Inside the groups, the researchers used their phony accounts to ask the real service members questions about their battalions and their work. They also used these accounts to “friend” service members. According to the report, Facebook’s Suggested Friends feature proved helpful in surfacing additional targets.

The researchers also tracked down service members’ Instagram and Twitter accounts and searched for other information available online, some of which a bad actor might be able to exploit. “We managed to find quite a lot of data on individual people, which would include sensitive information,” Biteniece says. “Like a serviceman having a wife and also being on dating apps.”

By the end of the exercise, the researchers identified 150 soldiers, found the locations of several battalions, tracked troop movements, and compelled service members to engage in “undesirable behavior,” including leaving their positions against orders.

“Every person has a button. For somebody there’s a financial issue, for somebody it’s a very appealing date, for somebody it’s a family thing,” Sarts says. “It’s varied, but everybody has a button. The point is, what’s openly available online is sufficient to know what that is.”

This is the future of warfare. It’s one of the reasons China stole all of that data from the Office of Personal Management. If indeed a country’s intelligence service was behind the Equifax attack, this is why they did it.

Go back and read this scenario from the Center for Strategic and International Studies. Why wouldn’t a country intent on starting a war do it that way?

Posted on February 26, 2019 at 6:10 AM • View Comments

Impersonating iOS Password Prompts

This is an interesting security vulnerability: because it is so easy to impersonate iOS password prompts, a malicious app can steal your password just by asking.

Why does this work?

iOS asks the user for their iTunes password for many reasons, the most common ones are recently installed iOS operating system updates, or iOS apps that are stuck during installation.

As a result, users are trained to just enter their Apple ID password whenever iOS prompts you to do so. However, those popups are not only shown on the lock screen, and the home screen, but also inside random apps, e.g. when they want to access iCloud, GameCenter or In-App-Purchases.

This could easily be abused by any app, just by showing an UIAlertController, that looks exactly like the system dialog.

Even users who know a lot about technology have a hard time detecting that those alerts are phishing attacks.

The essay proposes some solutions, but I’m not sure they’ll work. We’re all trained to trust our computers and the applications running on them.

Posted on October 12, 2017 at 6:43 AM • View Comments

Separating the Paranoid from the Hacked

Sad story of someone whose computer became owned by a griefer:

The trouble began last year when he noticed strange things happening: files went missing from his computer; his Facebook picture was changed; and texts from his daughter didn’t reach him or arrived changed.

“Nobody believed me,” says Gary. “My wife and my brother thought I had lost my mind. They scheduled an appointment with a psychiatrist for me.”

But he built up a body of evidence and called in a professional cybersecurity firm. It found that his email addresses had been compromised, his phone records hacked and altered, and an entire virtual internet interface created.

“All my communications were going through a man-in-the-middle unauthorised server,” he explains.

It’s the “psychiatrist” quote that got me. I regularly get e-mails from people explaining in graphic detail how their whole lives have been hacked. Most of them are just paranoid. But a few of them are probably legitimate. And I have no way of telling them apart.

This problem isn’t going away. As computers permeate even more aspects of our lives, it’s going to get even more debilitating. And we don’t have any way, other than hiring a “professional cybersecurity firm,” of telling the paranoids from the victims.

Posted on June 26, 2017 at 12:30 PM • View Comments

New Technique to Hijack Social Media Accounts

Access Now has documented it being used against a Twitter user, but it also works against other social media accounts:

With the Doubleswitch attack, a hijacker takes control of a victim’s account through one of several attack vectors. People who have not enabled an app-based form of multifactor authentication for their accounts are especially vulnerable. For instance, an attacker could trick you into revealing your password through phishing. If you don’t have multifactor authentication, you lack a secondary line of defense. Once in control, the hijacker can then send messages and also subtly change your account information, including your username. The original username for your account is now available, allowing the hijacker to register for an account using that original username, while providing different login credentials.

Three news stories.

Posted on June 19, 2017 at 6:44 AM • View Comments

Forging Voice

LyreBird is a system that can accurately reproduce the voice of someone, given a large amount of sample inputs. It’s pretty good—listen to the demo here—and will only get better over time.

The applications for recorded-voice forgeries are obvious, but I think the larger security risk will be real-time forgery. Imagine the social engineering implications of an attacker on the telephone being able to impersonate someone the victim knows.

I don’t think we’re ready for this. We use people’s voices to authenticate them all the time, in all sorts of different ways.

EDITED TO ADD (5/11): This is from 2003 on the topic.

Posted on May 4, 2017 at 10:31 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.