Entries Tagged "forgery"

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Forging Australian Driver’s Licenses

The New South Wales digital driver’s license has multiple implementation flaws that allow for easy forgeries.

This file is encrypted using AES-256-CBC encryption combined with Base64 encoding.

A 4-digit application PIN (which gets set during the initial onboarding when a user first instals the application) is the encryption password used to protect or encrypt the licence data.

The problem here is that an attacker who has access to the encrypted licence data (whether that be through accessing a phone backup, direct access to the device or remote compromise) could easily brute-force this 4-digit PIN by using a script that would try all 10,000 combinations….

[…]

The second design flaw that is favourable for attackers is that the Digital Driver Licence data is never validated against the back-end authority which is the Service NSW API/database.

This means that the application has no native method to validate the Digital Driver Licence data that exists on the phone and thus cannot perform further actions such as warn users when this data has been modified.

As the Digital Licence is stored on the client’s device, validation should take place to ensure the local copy of the data actually matches the Digital Driver’s Licence data that was originally downloaded from the Service NSW API.

As this verification does not take place, an attacker is able to display the edited data on the Service NSW application without any preventative factors.

There’s a lot more in the blog post.

Posted on May 23, 2022 at 6:09 AMView Comments

Java Cryptography Implementation Mistake Allows Digital-Signature Forgeries

Interesting implementation mistake:

The vulnerability, which Oracle patched on Tuesday, affects the company’s implementation of the Elliptic Curve Digital Signature Algorithm in Java versions 15 and above. ECDSA is an algorithm that uses the principles of elliptic curve cryptography to authenticate messages digitally.

[…]

ECDSA signatures rely on a pseudo-random number, typically notated as K, that’s used to derive two additional numbers, R and S. To verify a signature as valid, a party must check the equation involving R and S, the signer’s public key, and a cryptographic hash of the message. When both sides of the equation are equal, the signature is valid.

[…]

For the process to work correctly, neither R nor S can ever be a zero. That’s because one side of the equation is R, and the other is multiplied by R and a value from S. If the values are both 0, the verification check translates to 0 = 0 X (other values from the private key and hash), which will be true regardless of the additional values. That means an adversary only needs to submit a blank signature to pass the verification check successfully.

Madden wrote:

Guess which check Java forgot?

That’s right. Java’s implementation of ECDSA signature verification didn’t check if R or S were zero, so you could produce a signature value in which they are both 0 (appropriately encoded) and Java would accept it as a valid signature for any message and for any public key. The digital equivalent of a blank ID card.

More details.

Posted on April 22, 2022 at 7:09 AMView Comments

Hackers Using Fake Police Data Requests against Tech Companies

Brian Krebs has a detailed post about hackers using fake police data requests to trick companies into handing over data.

Virtually all major technology companies serving large numbers of users online have departments that routinely review and process such requests, which are typically granted as long as the proper documents are provided and the request appears to come from an email address connected to an actual police department domain name.

But in certain circumstances ­—such as a case involving imminent harm or death—­ an investigating authority may make what’s known as an Emergency Data Request (EDR), which largely bypasses any official review and does not require the requestor to supply any court-approved documents.

It is now clear that some hackers have figured out there is no quick and easy way for a company that receives one of these EDRs to know whether it is legitimate. Using their illicit access to police email systems, the hackers will send a fake EDR along with an attestation that innocent people will likely suffer greatly or die unless the requested data is provided immediately.

In this scenario, the receiving company finds itself caught between two unsavory outcomes: Failing to immediately comply with an EDR -­- and potentially having someone’s blood on their hands -­- or possibly leaking a customer record to the wrong person.

Another article claims that both Apple and Facebook (or Meta, or whatever they want to be called now) fell for this scam.

We allude to this kind of risk in our 2015 “Keys Under Doormats” paper:

Third, exceptional access would create concentrated targets that could attract bad actors. Security credentials that unlock the data would have to be retained by the platform provider, law enforcement agencies, or some other trusted third party. If law enforcement’s keys guaranteed access to everything, an attacker who gained access to these keys would enjoy the same privilege. Moreover, law enforcement’s stated need for rapid access to data would make it impractical to store keys offline or split keys among multiple keyholders, as security engineers would normally do with extremely high-value credentials.

The “credentials” are even more insecure than we could have imagined: access to an email address. And the data, of course, isn’t very secure. But imagine how this kind of thing could be abused with a law enforcement encryption backdoor.

Posted on April 5, 2022 at 6:04 AMView Comments

Why Vaccine Cards Are So Easily Forged

My proof of COVID-19 vaccination is recorded on an easy-to-forge paper card. With little trouble, I could print a blank form, fill it out, and snap a photo. Small imperfections wouldn’t pose any problem; you can’t see whether the paper’s weight is right in a digital image. When I fly internationally, I have to show a negative COVID-19 test result. That, too, would be easy to fake. I could change the date on an old test, or put my name on someone else’s test, or even just make something up on my computer. After all, there’s no standard format for test results; airlines accept anything that looks plausible.

After a career spent in cybersecurity, this is just how my mind works: I find vulnerabilities in everything I see. When it comes to the measures intended to keep us safe from COVID-19, I don’t even have to look very hard. But I’m not alarmed. The fact that these measures are flawed is precisely why they’re going to be so helpful in getting us past the pandemic.

Back in 2003, at the height of our collective terrorism panic, I coined the term security theater to describe measures that look like they’re doing something but aren’t. We did a lot of security theater back then: ID checks to get into buildings, even though terrorists have IDs; random bag searches in subway stations, forcing terrorists to walk to the next station; airport bans on containers with more than 3.4 ounces of liquid, which can be recombined into larger bottles on the other side of security. At first glance, asking people for photos of easily forged pieces of paper or printouts of readily faked test results might look like the same sort of security theater. There’s an important difference, though, between the most effective strategies for preventing terrorism and those for preventing COVID-19 transmission.

Security measures fail in one of two ways: Either they can’t stop a bad actor from doing a bad thing, or they block an innocent person from doing an innocuous thing. Sometimes one is more important than the other. When it comes to attacks that have catastrophic effects—say, launching nuclear missiles—we want the security to stop all bad actors, even at the expense of usability. But when we’re talking about milder attacks, the balance is less obvious. Sure, banks want credit cards to be impervious to fraud, but if the security measures also regularly prevent us from using our own credit cards, we would rebel and banks would lose money. So banks often put ease of use ahead of security.

That’s how we should think about COVID-19 vaccine cards and test documentation. We’re not looking for perfection. If most everyone follows the rules and doesn’t cheat, we win. Making these systems easy to use is the priority. The alternative just isn’t worth it.

I design computer security systems for a living. Given the challenge, I could design a system of vaccine and test verification that makes cheating very hard. I could issue cards that are as unforgeable as passports, or create phone apps that are linked to highly secure centralized databases. I could build a massive surveillance apparatus and enforce the sorts of strict containment measures used in China’s zero-COVID-19 policy. But the costs—in money, in liberty, in privacy—are too high. We can get most of the benefits with some pieces of paper and broad, but not universal, compliance with the rules.

It also helps that many of the people who break the rules are so very bad at it. Every story of someone getting arrested for faking a vaccine card, or selling a fake, makes it less likely that the next person will cheat. Every traveler arrested for faking a COVID-19 test does the same thing. When a famous athlete such as Novak Djokovic gets caught lying about his past COVID-19 diagnosis when trying to enter Australia, others conclude that they shouldn’t try lying themselves.

Our goal should be to impose the best policies that we can, given the trade-offs. The small number of cheaters isn’t going to be a public-health problem. I don’t even care if they feel smug about cheating the system. The system is resilient; it can withstand some cheating.

Last month, I visited New York City, where restrictions that are now being lifted were then still in effect. Every restaurant and cocktail bar I went to verified the photo of my vaccine card that I keep on my phone, and at least pretended to compare the name on that card with the one on my photo ID. I felt a lot safer in those restaurants because of that security theater, even if a few of my fellow patrons cheated.

This essay previously appeared in the Atlantic.

Posted on March 18, 2022 at 6:12 AMView Comments

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 AMView Comments

Signed Malware

Stuxnet famously used legitimate digital certificates to sign its malware. A research paper from last year found that the practice is much more common than previously thought.

Now, researchers have presented proof that digitally signed malware is much more common than previously believed. What’s more, it predated Stuxnet, with the first known instance occurring in 2003. The researchers said they found 189 malware samples bearing valid digital signatures that were created using compromised certificates issued by recognized certificate authorities and used to sign legitimate software. In total, 109 of those abused certificates remain valid. The researchers, who presented their findings Wednesday at the ACM Conference on Computer and Communications Security, found another 136 malware samples signed by legitimate CA-issued certificates, although the signatures were malformed.

The results are significant because digitally signed software is often able to bypass User Account Control and other Windows measures designed to prevent malicious code from being installed. Forged signatures also represent a significant breach of trust because certificates provide what’s supposed to be an unassailable assurance to end users that the software was developed by the company named in the certificate and hasn’t been modified by anyone else. The forgeries also allow malware to evade antivirus protections. Surprisingly, weaknesses in the majority of available AV programs prevented them from detecting known malware that was digitally signed even though the signatures weren’t valid.

Posted on February 2, 2018 at 6:38 AMView Comments

New Techniques in Fake Reviews

Research paper: “Automated Crowdturfing Attacks and Defenses in Online Review Systems.”

Abstract: Malicious crowdsourcing forums are gaining traction as sources of spreading misinformation online, but are limited by the costs of hiring and managing human workers. In this paper, we identify a new class of attacks that leverage deep learning language models (Recurrent Neural Networks or RNNs) to automate the generation of fake online reviews for products and services. Not only are these attacks cheap and therefore more scalable, but they can control rate of content output to eliminate the signature burstiness that makes crowdsourced campaigns easy to detect.

Using Yelp reviews as an example platform, we show how a two phased review generation and customization attack can produce reviews that are indistinguishable by state-of-the-art statistical detectors. We conduct a survey-based user study to show these reviews not only evade human detection, but also score high on “usefulness” metrics by users. Finally, we develop novel automated defenses against these attacks, by leveraging the lossy transformation introduced by the RNN training and generation cycle. We consider countermeasures against our mechanisms, show that they produce unattractive cost-benefit tradeoffs for attackers, and that they can be further curtailed by simple constraints imposed by online service providers.

Posted on September 4, 2017 at 7:08 AMView Comments

The Future of Forgeries

This article argues that AI technologies will make image, audio, and video forgeries much easier in the future.

Combined, the trajectory of cheap, high-quality media forgeries is worrying. At the current pace of progress, it may be as little as two or three years before realistic audio forgeries are good enough to fool the untrained ear, and only five or 10 years before forgeries can fool at least some types of forensic analysis. When tools for producing fake video perform at higher quality than today’s CGI and are simultaneously available to untrained amateurs, these forgeries might comprise a large part of the information ecosystem. The growth in this technology will transform the meaning of evidence and truth in domains across journalism, government communications, testimony in criminal justice, and, of course, national security.

I am not worried about fooling the “untrained ear,” and more worried about fooling forensic analysis. But there’s an arms race here. Recording technologies will get more sophisticated, too, making their outputs harder to forge. Still, I agree that the advantage will go to the forgers and not the forgery detectors.

Posted on July 10, 2017 at 6:04 AMView Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.