Facebook Is Using Your Two-Factor Authentication Phone Number to Target Advertising

From Kashmir Hill: Facebook is not content to use the contact information you willingly put into your Facebook profile for advertising. It is also using contact information you handed over for security purposes and contact information you didn’t hand over at all, but that was collected from other people’s contact books, a hidden layer of details Facebook has about you…

From Kashmir Hill:

Facebook is not content to use the contact information you willingly put into your Facebook profile for advertising. It is also using contact information you handed over for security purposes and contact information you didn't hand over at all, but that was collected from other people's contact books, a hidden layer of details Facebook has about you that I've come to call "shadow contact information." I managed to place an ad in front of Alan Mislove by targeting his shadow profile. This means that the junk email address that you hand over for discounts or for shady online shopping is likely associated with your account and being used to target you with ads.

Here's the research paper. Hill again:

They found that when a user gives Facebook a phone number for two-factor authentication or in order to receive alerts about new log-ins to a user's account, that phone number became targetable by an advertiser within a couple of weeks. So users who want their accounts to be more secure are forced to make a privacy trade-off and allow advertisers to more easily find them on the social network.

from https://www.schneier.com/blog/

E-Mail Vulnerabilities and Disclosure

Last week, researchers disclosed vulnerabilities in a large number of encrypted e-mail clients: specifically, those that use OpenPGP and S/MIME, including Thunderbird and AppleMail. These are serious vulnerabilities: An attacker who can alter mail sent to a vulnerable client can trick that client into sending a copy of the plaintext to a web server controlled by that attacker. The story…

Last week, researchers disclosed vulnerabilities in a large number of encrypted e-mail clients: specifically, those that use OpenPGP and S/MIME, including Thunderbird and AppleMail. These are serious vulnerabilities: An attacker who can alter mail sent to a vulnerable client can trick that client into sending a copy of the plaintext to a web server controlled by that attacker. The story of these vulnerabilities and the tale of how they were disclosed illustrate some important lessons about security vulnerabilities in general and e-mail security in particular.

But first, if you use PGP or S/MIME to encrypt e-mail, you need to check the list on this page and see if you are vulnerable. If you are, check with the vendor to see if they've fixed the vulnerability. (Note that some early patches turned out not to fix the vulnerability.) If not, stop using the encrypted e-mail program entirely until it's fixed. Or, if you know how to do it, turn off your e-mail client's ability to process HTML e-mail or -- even better -- stop decrypting e-mails from within the client. There's even more complex advice for more sophisticated users, but if you're one of those, you don't need me to explain this to you.

Consider your encrypted e-mail insecure until this is fixed.

All software contains security vulnerabilities, and one of the primary ways we all improve our security is by researchers discovering those vulnerabilities and vendors patching them. It's a weird system: Corporate researchers are motivated by publicity, academic researchers by publication credentials, and just about everyone by individual fame and the small bug-bounties paid by some vendors.

Software vendors, on the other hand, are motivated to fix vulnerabilities by the threat of public disclosure. Without the threat of eventual publication, vendors are likely to ignore researchers and delay patching. This happened a lot in the 1990s, and even today, vendors often use legal tactics to try to block publication. It makes sense; they look bad when their products are pronounced insecure.

Over the past few years, researchers have started to choreograph vulnerability announcements to make a big press splash. Clever names -- the e-mail vulnerability is called "Efail" -- websites, and cute logos are now common. Key reporters are given advance information about the vulnerabilities. Sometimes advance teasers are released. Vendors are now part of this process, trying to announce their patches at the same time the vulnerabilities are announced.

This simultaneous announcement is best for security. While it's always possible that some organization -- either government or criminal -- has independently discovered and is using the vulnerability before the researchers go public, use of the vulnerability is essentially guaranteed after the announcement. The time period between announcement and patching is the most dangerous, and everyone except would-be attackers wants to minimize it.

Things get much more complicated when multiple vendors are involved. In this case, Efail isn't a vulnerability in a particular product; it's a vulnerability in a standard that is used in dozens of different products. As such, the researchers had to ensure both that everyone knew about the vulnerability in time to fix it and that no one leaked the vulnerability to the public during that time. As you can imagine, that's close to impossible.

Efail was discovered sometime last year, and the researchers alerted dozens of different companies between last October and March. Some companies took the news more seriously than others. Most patched. Amazingly, news about the vulnerability didn't leak until the day before the scheduled announcement date. Two days before the scheduled release, the researchers unveiled a teaser -- honestly, a really bad idea -- which resulted in details leaking.

After the leak, the Electronic Frontier Foundation posted a notice about the vulnerability without details. The organization has been criticized for its announcement, but I am hard-pressed to find fault with its advice. (Note: I am a board member at EFF.) Then, the researchers published -- and lots of press followed.

All of this speaks to the difficulty of coordinating vulnerability disclosure when it involves a large number of companies or -- even more problematic -- communities without clear ownership. And that's what we have with OpenPGP. It's even worse when the bug involves the interaction between different parts of a system. In this case, there's nothing wrong with PGP or S/MIME in and of themselves. Rather, the vulnerability occurs because of the way many e-mail programs handle encrypted e-mail. GnuPG, an implementation of OpenPGP, decided that the bug wasn't its fault and did nothing about it. This is arguably true, but irrelevant. They should fix it.

Expect more of these kinds of problems in the future. The Internet is shifting from a set of systems we deliberately use -- our phones and computers -- to a fully immersive Internet-of-things world that we live in 24/7. And like this e-mail vulnerability, vulnerabilities will emerge through the interactions of different systems. Sometimes it will be obvious who should fix the problem. Sometimes it won't be. Sometimes it'll be two secure systems that, when they interact in a particular way, cause an insecurity. In April, I wrote about a vulnerability that arose because Google and Netflix make different assumptions about e-mail addresses. I don't even know who to blame for that one.

It gets even worse. Our system of disclosure and patching assumes that vendors have the expertise and ability to patch their systems, but that simply isn't true for many of the embedded and low-cost Internet of things software packages. They're designed at a much lower cost, often by offshore teams that come together, create the software, and then disband; as a result, there simply isn't anyone left around to receive vulnerability alerts from researchers and write patches. Even worse, many of these devices aren't patchable at all. Right now, if you own a digital video recorder that's vulnerable to being recruited for a botnet -- remember Mirai from 2016? -- the only way to patch it is to throw it away and buy a new one.

Patching is starting to fail, which means that we're losing the best mechanism we have for improving software security at exactly the same time that software is gaining autonomy and physical agency. Many researchers and organizations, including myself, have proposed government regulations enforcing minimal security standards for Internet-of-things devices, including standards around vulnerability disclosure and patching. This would be expensive, but it's hard to see any other viable alternative.

Getting back to e-mail, the truth is that it's incredibly difficult to secure well. Not because the cryptography is hard, but because we expect e-mail to do so many things. We use it for correspondence, for conversations, for scheduling, and for record-keeping. I regularly search my 20-year e-mail archive. The PGP and S/MIME security protocols are outdated, needlessly complicated and have been difficult to properly use the whole time. If we could start again, we would design something better and more user friendly­but the huge number of legacy applications that use the existing standards mean that we can't. I tell people that if they want to communicate securely with someone, to use one of the secure messaging systems: Signal, Off-the-Record, or -- if having one of those two on your system is itself suspicious -- WhatsApp. Of course they're not perfect, as last week's announcement of a vulnerability (patched within hours) in Signal illustrates. And they're not as flexible as e-mail, but that makes them easier to secure.

This essay previously appeared on Lawfare.com.

from https://www.schneier.com/blog/

Details on a New PGP Vulnerability

A new PGP vulnerability was announced today. Basically, the vulnerability makes use of the fact that modern e-mail programs allow for embedded HTML objects. Essentially, if an attacker can intercept and modify a message in transit, he can insert code that sends the plaintext in a URL to a remote website. Very clever. The EFAIL attacks exploit vulnerabilities in the…

A new PGP vulnerability was announced today. Basically, the vulnerability makes use of the fact that modern e-mail programs allow for embedded HTML objects. Essentially, if an attacker can intercept and modify a message in transit, he can insert code that sends the plaintext in a URL to a remote website. Very clever.

The EFAIL attacks exploit vulnerabilities in the OpenPGP and S/MIME standards to reveal the plaintext of encrypted emails. In a nutshell, EFAIL abuses active content of HTML emails, for example externally loaded images or styles, to exfiltrate plaintext through requested URLs. To create these exfiltration channels, the attacker first needs access to the encrypted emails, for example, by eavesdropping on network traffic, compromising email accounts, email servers, backup systems or client computers. The emails could even have been collected years ago.

The attacker changes an encrypted email in a particular way and sends this changed encrypted email to the victim. The victim's email client decrypts the email and loads any external content, thus exfiltrating the plaintext to the attacker.

A few initial comments:

1. Being able to intercept and modify e-mails in transit is the sort of thing the NSA can do, but is hard for the average hacker. That being said, there are circumstances where someone can modify e-mails. I don't mean to minimize the seriousness of this attack, but that is a consideration.

2. The vulnerability isn't with PGP or S/MIME itself, but in the way they interact with modern e-mail programs. You can see this in the two suggested short-term mitigations: "No decryption in the e-mail client," and "disable HTML rendering."

3. I've been getting some weird press calls from reporters wanting to know if this demonstrates that e-mail encryption is impossible. No, this just demonstrates that programmers are human and vulnerabilities are inevitable. PGP almost certainly has fewer bugs than your average piece of software, but it's not bug free.

3. Why is anyone using encrypted e-mail anymore, anyway? Reliably and easily encrypting e-mail is an insurmountably hard problem for reasons having nothing to do with today's announcement. If you need to communicate securely, use Signal. If having Signal on your phone will arouse suspicion, use WhatsApp.

I'll post other commentaries and analyses as I find them.

from https://www.schneier.com/blog/

Critical PGP Vulnerability

EFF is reporting that a critical vulnerability has been discovered in PGP and S/MIME. No details have been published yet, but one of the researchers wrote: We’ll publish critical vulnerabilities in PGP/GPG and S/MIME email encryption on 2018-05-15 07:00 UTC. They might reveal the plaintext of encrypted emails, including encrypted emails sent in the past. There are currently no reliable…

EFF is reporting that a critical vulnerability has been discovered in PGP and S/MIME. No details have been published yet, but one of the researchers wrote:

We'll publish critical vulnerabilities in PGP/GPG and S/MIME email encryption on 2018-05-15 07:00 UTC. They might reveal the plaintext of encrypted emails, including encrypted emails sent in the past. There are currently no reliable fixes for the vulnerability. If you use PGP/GPG or S/MIME for very sensitive communication, you should disable it in your email client for now.

This sounds like a protocol vulnerability, but we'll learn more tomorrow.

News articles.

from https://www.schneier.com/blog/

Obscure E-Mail Vulnerability

This vulnerability is a result of an interaction between two different ways of handling e-mail addresses. Gmail ignores dots in addresses, so bruce.schneier@gmail.com is the same as bruceschneier@gmail.com is the same as b.r.u.c.e.schneier@gmail.com. (Note: I do not own any of those email addresses — if they’re even valid.) Netflix doesn’t ignore dots, so those are all unique e-mail addresses and…

This vulnerability is a result of an interaction between two different ways of handling e-mail addresses. Gmail ignores dots in addresses, so bruce.schneier@gmail.com is the same as bruceschneier@gmail.com is the same as b.r.u.c.e.schneier@gmail.com. (Note: I do not own any of those email addresses -- if they're even valid.) Netflix doesn't ignore dots, so those are all unique e-mail addresses and can each be used to register an account. This difference can be exploited.

I was almost fooled into perpetually paying for Eve's Netflix access, and only paused because I didn't recognize the declined card. More generally, the phishing scam here is:

  1. Hammer the Netflix signup form until you find a gmail.com address which is "already registered". Let's say you find the victim jameshfisher.
  2. Create a Netflix account with address james.hfisher.
  3. Sign up for free trial with a throwaway card number.
  4. After Netflix applies the "active card check", cancel the card.
  5. Wait for Netflix to bill the cancelled card. Then Netflix emails james.hfisher asking for a valid card.
  6. Hope Jim reads the email to james.hfisher, assumes it's for his Netflix account backed by jameshfisher, then enters his card **** 1234.
  7. Change the email for the Netflix account to eve@gmail.com, kicking Jim's access to this account.
  8. Use Netflix free forever with Jim's card **** 1234!

Obscure, yes? A problem, yes?

James Fisher, who wrote the post, argues that it's Google's fault. Ignoring dots might give people an enormous number of different email addresses, but it's not a feature that people actually want. And as long as other sites don't follow Google's lead, these sorts of problems are possible.

I think the problem is more subtle. It's an example of two systems without a security vulnerability coming together to create a security vulnerability. As we connect more systems directly to each other, we're going to see a lot more of these. And like this Google/Netflix interaction, it's going to be hard to figure out who to blame and who -- if anyone -- has the responsibility of fixing it.

from https://www.schneier.com/blog/

E-Mailing Private HTTPS Keys

I don’t know what to make of this story: The email was sent on Tuesday by the CEO of Trustico, a UK-based reseller of TLS certificates issued by the browser-trusted certificate authorities Comodo and, until recently, Symantec. It was sent to Jeremy Rowley, an executive vice president at DigiCert, a certificate authority that acquired Symantec’s certificate issuance business after Symantec…

I don't know what to make of this story:

The email was sent on Tuesday by the CEO of Trustico, a UK-based reseller of TLS certificates issued by the browser-trusted certificate authorities Comodo and, until recently, Symantec. It was sent to Jeremy Rowley, an executive vice president at DigiCert, a certificate authority that acquired Symantec's certificate issuance business after Symantec was caught flouting binding industry rules, prompting Google to distrust Symantec certificates in its Chrome browser. In communications earlier this month, Trustico notified DigiCert that 50,000 Symantec-issued certificates Trustico had resold should be mass revoked because of security concerns.

When Rowley asked for proof the certificates were compromised, the Trustico CEO emailed the private keys of 23,000 certificates, according to an account posted to a Mozilla security policy forum. The report produced a collective gasp among many security practitioners who said it demonstrated a shockingly cavalier treatment of the digital certificates that form one of the most basic foundations of website security.

Generally speaking, private keys for TLS certificates should never be archived by resellers, and, even in the rare cases where such storage is permissible, they should be tightly safeguarded. A CEO being able to attach the keys for 23,000 certificates to an email raises troubling concerns that those types of best practices weren't followed.

I am croggled by the multiple layers of insecurity here.

BoingBoing post.

from https://www.schneier.com/blog/

E-Mail Tracking

Good article on the history and practice of e-mail tracking: The tech is pretty simple. Tracking clients embed a line of code in the body of an email­ — usually in a 1×1 pixel image, so tiny it’s invisible, but also in elements like hyperlinks and custom fonts. When a recipient opens the email, the tracking client recognizes that pixel…

Good article on the history and practice of e-mail tracking:

The tech is pretty simple. Tracking clients embed a line of code in the body of an email­ -- usually in a 1x1 pixel image, so tiny it's invisible, but also in elements like hyperlinks and custom fonts. When a recipient opens the email, the tracking client recognizes that pixel has been downloaded, as well as where and on what device. Newsletter services, marketers, and advertisers have used the technique for years, to collect data about their open rates; major tech companies like Facebook and Twitter followed suit in their ongoing quest to profile and predict our behavior online.

But lately, a surprising­ -- and growing­ -- number of tracked emails are being sent not from corporations, but acquaintances. "We have been in touch with users that were tracked by their spouses, business partners, competitors," says Florian Seroussi, the founder of OMC. "It's the wild, wild west out there."

According to OMC's data, a full 19 percent of all "conversational" email is now tracked. That's one in five of the emails you get from your friends. And you probably never noticed.

I admit it's enticing. I would very much like the statistics that adding trackers to Crypto-Gram would give me. But I still don't do it.

from https://www.schneier.com/blog/

Cybercriminals Infiltrating E-Mail Networks to Divert Large Customer Payments

There’s a new criminal tactic involving hacking an e-mail account of a company that handles high-value transactions and diverting payments. Here it is in real estate: The scam generally works like this: Hackers find an opening into a title company’s or realty agent’s email account, track upcoming home purchases scheduled for settlements — the pricier the better — then assume…

There's a new criminal tactic involving hacking an e-mail account of a company that handles high-value transactions and diverting payments. Here it is in real estate:

The scam generally works like this: Hackers find an opening into a title company's or realty agent's email account, track upcoming home purchases scheduled for settlements -- the pricier the better -- then assume the identity of the title agency person handling the transaction.

Days or sometimes weeks before the settlement, the scammer poses as the title or escrow agent whose email accounts they've hijacked and instructs the home buyer to wire the funds needed to close -- often hundreds of thousands of dollars, sometimes far more -- to the criminals' own bank accounts, not the title or escrow company's legitimate accounts. The criminals then withdraw the money and vanish.

Here it is in fine art:

The fraud is relatively simple. Criminals hack into an art dealer's email account and monitor incoming and outgoing correspondence. When the gallery sends a PDF invoice to a client via email following a sale, the conversation is hijacked. Posing as the gallery, hackers send a duplicate, fraudulent invoice from the same gallery email address, with an accompanying message instructing the client to disregard the first invoice and instead wire payment to the account listed in the fraudulent document.

Once money has been transferred to the criminals' account, the hackers move the money to avoid detection and then disappear. The same technique is used to intercept payments made by galleries to their artists and others. Because the hackers gain access to the gallery's email contacts, the scam can spread quickly, with fraudulent emails appearing to come from known sources.

I'm sure it's happening in other industries as well, probably even with business-to-business commerce.

EDITED TO ADD (11/14): Brian Krebs wrote about this in 2014.

from https://www.schneier.com/blog/

Journalists Generally Do Not Use Secure Communication

This should come as no surprise: Alas, our findings suggest that secure communications haven’t yet attracted mass adoption among journalists. We looked at 2,515 Washington journalists with permanent credentials to cover Congress, and we found only 2.5 percent of them solicit end-to-end encrypted communication via their Twitter bios. That’s just 62 out of all the broadcast, newspaper, wire service, and…

This should come as no surprise:

Alas, our findings suggest that secure communications haven't yet attracted mass adoption among journalists. We looked at 2,515 Washington journalists with permanent credentials to cover Congress, and we found only 2.5 percent of them solicit end-to-end encrypted communication via their Twitter bios. That's just 62 out of all the broadcast, newspaper, wire service, and digital reporters. Just 28 list a way to reach them via Signal or another secure messaging app. Only 22 provide a PGP public key, a method that allows sources to send encrypted messages. A paltry seven advertise a secure email address. In an era when anything that can be hacked will be and when the president has declared outright war on the media, this should serve as a frightening wake-up call.

[...]

When journalists don't step up, sources with sensitive information face the burden of using riskier modes of communication to initiate contact­ -- and possibly conduct all of their exchanges­ -- with reporters. It increases their chances of getting caught, putting them in danger of losing their job or facing prosecution. It's burden enough to make them think twice about whistleblowing.

I forgive them for not using secure e-mail. It's hard to use and confusing. But secure messaging is easy.

from https://www.schneier.com/blog/