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WhatsApp Vulnerability Fixed

WhatsApp fixed a devastating vulnerability that allowed someone to remotely hack a phone by initiating a WhatsApp voice call. The recipient didn’t even have to answer the call.

The Israeli cyber-arms manufacturer NSO Group is believed to be behind the exploit, but of course there is no definitive proof.

If you use WhatsApp, update your app immediately.

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Judging Facebook’s Privacy Shift

Facebook is making a new and stronger commitment to privacy. Last month, the company hired three of its most vociferous critics and installed them in senior technical positions. And on Wednesday, Mark Zuckerberg wrote that the company will pivot to focus on private conversations over the public sharing that has long defined the platform, even while conceding that “frankly we don’t currently have a strong reputation for building privacy protective services.”

There is ample reason to question Zuckerberg’s pronouncement: The company has made — and broken — many privacy promises over the years. And if you read his 3,000-word post carefully, Zuckerberg says nothing about changing Facebook’s surveillance capitalism business model. All the post discusses is making private chats more central to the company, which seems to be a play for increased market dominance and to counter the Chinese company WeChat.

In security and privacy, the devil is always in the details — and Zuckerberg’s post provides none. But we’ll take him at his word and try to fill in some of the details here. What follows is a list of changes we should expect if Facebook is serious about changing its business model and improving user privacy.

How Facebook treats people on its platform

Increased transparency over advertiser and app accesses to user data. Today, Facebook users can download and view much of the data the company has about them. This is important, but it doesn’t go far enough. The company could be more transparent about what data it shares with advertisers and others and how it allows advertisers to select users they show ads to. Facebook could use its substantial skills in usability testing to help people understand the mechanisms advertisers use to show them ads or the reasoning behind what it chooses to show in user timelines. It could deliver on promises in this area.

Better — and more usable — privacy options. Facebook users have limited control over how their data is shared with other Facebook users and almost no control over how it is shared with Facebook’s advertisers, which are the company’s real customers. Moreover, the controls are buried deep behind complex and confusing menu options. To be fair, some of this is because privacy is complex, and it’s hard to understand the results of different options. But much of this is deliberate; Facebook doesn’t want its users to make their data private from other users.

The company could give people better control over how — and whether — their data is used, shared, and sold. For example, it could allow users to turn off individually targeted news and advertising. By this, we don’t mean simply making those advertisements invisible; we mean turning off the data flows into those tailoring systems. Finally, since most users stick to the default options when it comes to configuring their apps, a changing Facebook could tilt those defaults toward more privacy, requiring less tailoring most of the time.

More user protection from stalking. “Facebook stalking” is often thought of as “stalking light,” or “harmless.” But stalkers are rarely harmless. Facebook should acknowledge this class of misuse and work with experts to build tools that protect all of its users, especially its most vulnerable ones. Such tools should guide normal people away from creepiness and give victims power and flexibility to enlist aid from sources ranging from advocates to police.

Fully ending real-name enforcement. Facebook’s real-names policy, requiring people to use their actual legal names on the platform, hurts people such as activists, victims of intimate partner violence, police officers whose work makes them targets, and anyone with a public persona who wishes to have control over how they identify to the public. There are many ways Facebook can improve on this, from ending enforcement to allowing verifying pseudonyms for everyone­ — not just celebrities like Lady Gaga. Doing so would mark a clear shift.

How Facebook runs its platform

Increased transparency of Facebook’s business practices. One of the hard things about evaluating Facebook is the effort needed to get good information about its business practices. When violations are exposed by the media, as they regularly are, we are all surprised at the different ways Facebook violates user privacy. Most recently, the company used phone numbers provided for two-factor authentication for advertising and networking purposes. Facebook needs to be both explicit and detailed about how and when it shares user data. In fact, a move from discussing “sharing” to discussing “transfers,” “access to raw information,” and “access to derived information” would be a visible improvement.

Increased transparency regarding censorship rules. Facebook makes choices about what content is acceptable on its site. Those choices are controversial, implemented by thousands of low-paid workers quickly implementing unclear rules. These are tremendously hard problems without clear solutions. Even obvious rules like banning hateful words run into challenges when people try to legitimately discuss certain important topics. Whatever Facebook does in this regard, the company needs be more transparent about its processes. It should allow regulators and the public to audit the company’s practices. Moreover, Facebook should share any innovative engineering solutions with the world, much as it currently shares its data center engineering.

Better security for collected user data. There have been numerous examples of attackers targeting cloud service platforms to gain access to user data. Facebook has a large and skilled product security team that says some of the right things. That team needs to be involved in the design trade-offs for features and not just review the near-final designs for flaws. Shutting down a feature based on internal security analysis would be a clear message.

Better data security so Facebook sees less. Facebook eavesdrops on almost every aspect of its users’ lives. On the other hand, WhatsApp — purchased by Facebook in 2014 — provides users with end-to-end encrypted messaging. While Facebook knows who is messaging whom and how often, Facebook has no way of learning the contents of those messages. Recently, Facebook announced plans to combine WhatsApp, Facebook Messenger, and Instagram, extending WhatsApp’s security to the consolidated system. Changing course here would be a dramatic and negative signal.

Collecting less data from outside of Facebook. Facebook doesn’t just collect data about you when you’re on the platform. Because its “like” button is on so many other pages, the company can collect data about you when you’re not on Facebook. It even collects what it calls “shadow profiles” — data about you even if you’re not a Facebook user. This data is combined with other surveillance data the company buys, including health and financial data. Collecting and saving less of this data would be a strong indicator of a new direction for the company.

Better use of Facebook data to prevent violence. There is a trade-off between Facebook seeing less and Facebook doing more to prevent hateful and inflammatory speech. Dozens of people have been killed by mob violence because of fake news spread on WhatsApp. If Facebook were doing a convincing job of controlling fake news without end-to-end encryption, then we would expect to hear how it could use patterns in metadata to handle encrypted fake news.

How Facebook manages for privacy

Create a team measured on privacy and trust. Where companies spend their money tells you what matters to them. Facebook has a large and important growth team, but what team, if any, is responsible for privacy, not as a matter of compliance or pushing the rules, but for engineering? Transparency in how it is staffed relative to other teams would be telling.

Hire a senior executive responsible for trust. Facebook’s current team has been focused on growth and revenue. Its one chief security officer, Alex Stamos, was not replaced when he left in 2018, which may indicate that having an advocate for security on the leadership team led to debate and disagreement. Retaining a voice for security and privacy issues at the executive level, before those issues affected users, was a good thing. Now that responsibility is diffuse. It’s unclear how Facebook measures and assesses its own progress and who might be held accountable for failings. Facebook can begin the process of fixing this by designating a senior executive who is responsible for trust.

Engage with regulators. Much of Facebook’s posturing seems to be an attempt to forestall regulation. Facebook sends lobbyists to Washington and other capitals, and until recently the company sent support staff to politician’s offices. It has secret lobbying campaigns against privacy laws. And Facebook has repeatedly violated a 2011 Federal Trade Commission consent order regarding user privacy. Regulating big technical projects is not easy. Most of the people who understand how these systems work understand them because they build them. Societies will regulate Facebook, and the quality of that regulation requires real education of legislators and their staffs. While businesses often want to avoid regulation, any focus on privacy will require strong government oversight. If Facebook is serious about privacy being a real interest, it will accept both government regulation and community input.

User privacy is traditionally against Facebook’s core business interests. Advertising is its business model, and targeted ads sell better and more profitably — and that requires users to engage with the platform as much as possible. Increased pressure on Facebook to manage propaganda and hate speech could easily lead to more surveillance. But there is pressure in the other direction as well, as users equate privacy with increased control over how they present themselves on the platform.

We don’t expect Facebook to abandon its advertising business model, relent in its push for monopolistic dominance, or fundamentally alter its social networking platforms. But the company can give users important privacy protections and controls without abandoning surveillance capitalism. While some of these changes will reduce profits in the short term, we hope Facebook’s leadership realizes that they are in the best long-term interest of the company.

Facebook talks about community and bringing people together. These are admirable goals, and there’s plenty of value (and profit) in having a sustainable platform for connecting people. But as long as the most important measure of success is short-term profit, doing things that help strengthen communities will fall by the wayside. Surveillance, which allows individually targeted advertising, will be prioritized over user privacy. Outrage, which drives engagement, will be prioritized over feelings of belonging. And corporate secrecy, which allows Facebook to evade both regulators and its users, will be prioritized over societal oversight. If Facebook now truly believes that these latter options are critical to its long-term success as a company, we welcome the changes that are forthcoming.

This essay was co-authored with Adam Shostack, and originally appeared on Medium OneZero. We wrote a similar essay in 2002 about judging Microsoft’s then newfound commitment to security.

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Russian Censorship of Telegram

Internet censors have a new strategy in their bid to block applications and websites: pressuring the large cloud providers that host them. These providers have concerns that are much broader than the targets of censorship efforts, so they have the choice of either standing up to the censors or capitulating in order to maximize their business. Today’s Internet largely reflects the dominance of a handful of companies behind the cloud services, search engines and mobile platforms that underpin the technology landscape. This new centralization radically tips the balance between those who want to censor parts of the Internet and those trying to evade censorship. When the profitable answer is for a software giant to acquiesce to censors’ demands, how long can Internet freedom last?

The recent battle between the Russian government and the Telegram messaging app illustrates one way this might play out. Russia has been trying to block Telegram since April, when a Moscow court banned it after the company refused to give Russian authorities access to user messages. Telegram, which is widely used in Russia, works on both iPhone and Android, and there are Windows and Mac desktop versions available. The app offers optional end-to-end encryption, meaning that all messages are encrypted on the sender’s phone and decrypted on the receiver’s phone; no part of the network can eavesdrop on the messages.

Since then, Telegram has been playing cat-and-mouse with the Russian telecom regulator Roskomnadzor by varying the IP address the app uses to communicate. Because Telegram isn’t a fixed website, it doesn’t need a fixed IP address. Telegram bought tens of thousands of IP addresses and has been quickly rotating through them, staying a step ahead of censors. Cleverly, this tactic is invisible to users. The app never sees the change, or the entire list of IP addresses, and the censor has no clear way to block them all.

A week after the court ban, Roskomnadzor countered with an unprecedented move of its own: blocking 19 million IP addresses, many on Amazon Web Services and Google Cloud. The collateral damage was widespread: The action inadvertently broke many other web services that use those platforms, and Roskomnadzor scaled back after it became clear that its action had affected services critical for Russian business. Even so, the censor is still blocking millions of IP addresses.

More recently, Russia has been pressuring Apple not to offer the Telegram app in its iPhone App Store. As of this writing, Apple has not complied, and the company has allowed Telegram to download a critical software update to iPhone users (after what the app’s founder called a delay last month). Roskomnadzor could further pressure Apple, though, including by threatening to turn off its entire iPhone app business in Russia.

Telegram might seem a weird app for Russia to focus on. Those of us who work in security don’t recommend the program, primarily because of the nature of its cryptographic protocols. In general, proprietary cryptography has numerous fatal security flaws. We generally recommend Signal for secure SMS messaging, or, if having that program on your computer is somehow incriminating, WhatsApp. (More than 1.5 billion people worldwide use WhatsApp.) What Telegram has going for it is that it works really well on lousy networks. That’s why it is so popular in places like Iran and Afghanistan. (Iran is also trying to ban the app.)

What the Russian government doesn’t like about Telegram is its anonymous broadcast feature­ — channel capability and chats — ­which makes it an effective platform for political debate and citizen journalism. The Russians might not like that Telegram is encrypted, but odds are good that they can simply break the encryption. Telegram’s role in facilitating uncontrolled journalism is the real issue.

Iran attempts to block Telegram have been more successful than Russia’s, less because Iran’s censorship technology is more sophisticated but because Telegram is not willing to go as far to defend Iranian users. The reasons are not rooted in business decisions. Simply put, Telegram is a Russian product and the designers are more motivated to poke Russia in the eye. Pavel Durov, Telegram’s founder, has pledged millions of dollars to help fight Russian censorship.

For the moment, Russia has lost. But this battle is far from over. Russia could easily come back with more targeted pressure on Google, Amazon and Apple. A year earlier, Zello used the same trick Telegram is using to evade Russian censors. Then, Roskomnadzor threatened to block all of Amazon Web Services and Google Cloud; and in that instance, both companies forced Zello to stop its IP-hopping censorship-evasion tactic.

Russia could also further develop its censorship infrastructure. If its capabilities were as finely honed as China’s, it would be able to more effectively block Telegram from operating. Right now, Russia can block only specific IP addresses, which is too coarse a tool for this issue. Telegram’s voice capabilities in Russia are significantly degraded, however, probably because high-capacity IP addresses are easier to block.

Whatever its current frustrations, Russia might well win in the long term. By demonstrating its willingness to suffer the temporary collateral damage of blocking major cloud providers, it prompted cloud providers to block another and more effective anti-censorship tactic, or at least accelerated the process. In April, Google and Amazon banned­ — and technically blocked­ — the practice of “domain fronting,” a trick anti-censorship tools use to get around Internet censors by pretending to be other kinds of traffic. Developers would use popular websites as a proxy, routing traffic to their own servers through another website­ — in this case Google.com­ — to fool censors into believing the traffic was intended for Google.com. The anonymous web-browsing tool Tor has used domain fronting since 2014. Signal, since 2016. Eliminating the capability is a boon to censors worldwide.

Tech giants have gotten embroiled in censorship battles for years. Sometimes they fight and sometimes they fold, but until now there have always been options. What this particular fight highlights is that Internet freedom is increasingly in the hands of the world’s largest Internet companies. And while freedom may have its advocates — ­the American Civil Liberties Union has tweeted its support for those companies, and some 12,000 people in Moscow protested against the Telegram ban­ — actions such as disallowing domain fronting illustrate that getting the big tech companies to sacrifice their near-term commercial interests will be an uphill battle. Apple has already removed anti-censorship apps from its Chinese app store.

In 1993, John Gilmore famously said that “The Internet interprets censorship as damage and routes around it.” That was technically true when he said it but only because the routing structure of the Internet was so distributed. As centralization increases, the Internet loses that robustness, and censorship by governments and companies becomes easier.

This essay previously appeared on Lawfare.com.

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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 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.

EDITED TO ADD (5/14): News articles.

Slashdot thread.

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WhatsApp Vulnerability

A new vulnerability in WhatsApp has been discovered:

…the researchers unearthed far more significant gaps in WhatsApp’s security: They say that anyone who controls WhatsApp’s servers could effortlessly insert new people into an otherwise private group, even without the permission of the administrator who ostensibly controls access to that conversation.

Matthew Green has a good description:

If all you want is the TL;DR, here’s the headline finding: due to flaws in both Signal and WhatsApp (which I single out because I use them), it’s theoretically possible for strangers to add themselves to an encrypted group chat. However, the caveat is that these attacks are extremely difficult to pull off in practice, so nobody needs to panic. But both issues are very avoidable, and tend to undermine the logic of having an end-to-end encryption protocol in the first place.

Here’s the research paper.

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Daphne Caruana Galizia’s Murder and the Security of WhatsApp

Daphne Caruana Galizia was a Maltese journalist whose anti-corruption investigations exposed powerful people. She was murdered in October by a car bomb.

Galizia used WhatsApp to communicate securely with her sources. Now that she is dead, the Maltese police want to break into her phone or the app, and find out who those sources were.

One journalist reports:

Part of Daphne’s destroyed smart phone was elevated from the scene.

Investigators say that Caruana Galizia had not taken her laptop with her on that particular trip. If she had done so, the forensic experts would have found evidence on the ground.

Her mobile phone is also being examined, as can be seen from her WhatsApp profile, which has registered activity since the murder. But it is understood that the data is safe.

Sources close to the newsroom said that as part of the investigation her sim card has been cloned. This is done with the help of mobile service providers in similar cases. Asked if her WhatsApp messages or any other messages that were stored in her phone will be retrieved, the source said that since the messaging application is encrypted, the messages cannot be seen. Therefore it is unlikely that any data can be retrieved.

I am less optimistic than that reporter. The FBI is providing “specific assistance.” The article doesn’t explain that, but I would not be surprised if they were helping crack the phone.

It will be interesting to see if WhatsApp’s security survives this. My guess is that it depends on how much of the phone was recovered from the bombed car.

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WhatsApp Security Vulnerability

Back in March, Rolf Weber wrote about a potential vulnerability in the WhatsApp protocol that would allow Facebook to defeat perfect forward secrecy by forcibly change users’ keys, allowing it — or more likely, the government — to eavesdrop on encrypted messages.

It seems that this vulnerability is real:

WhatsApp has the ability to force the generation of new encryption keys for offline users, unbeknown to the sender and recipient of the messages, and to make the sender re-encrypt messages with new keys and send them again for any messages that have not been marked as delivered.

The recipient is not made aware of this change in encryption, while the sender is only notified if they have opted-in to encryption warnings in settings, and only after the messages have been re-sent. This re-encryption and rebroadcasting effectively allows WhatsApp to intercept and read users’ messages.

The security loophole was discovered by Tobias Boelter, a cryptography and security researcher at the University of California, Berkeley. He told the Guardian: “If WhatsApp is asked by a government agency to disclose its messaging records, it can effectively grant access due to the change in keys.”

The vulnerability is not inherent to the Signal protocol. Open Whisper Systems’ messaging app, Signal, the app used and recommended by whistleblower Edward Snowden, does not suffer from the same vulnerability. If a recipient changes the security key while offline, for instance, a sent message will fail to be delivered and the sender will be notified of the change in security keys without automatically resending the message.

WhatsApp’s implementation automatically resends an undelivered message with a new key without warning the user in advance or giving them the ability to prevent it.

Note that it’s an attack against current and future messages, and not something that would allow the government to reach into the past. In that way, it is no more troubling than the government hacking your mobile phone and reading your WhatsApp conversations that way.

An unnamed “WhatsApp spokesperson” said that they implemented the encryption this way for usability:

In WhatsApp’s implementation of the Signal protocol, we have a “Show Security Notifications” setting (option under Settings > Account > Security) that notifies you when a contact’s security code has changed. We know the most common reasons this happens are because someone has switched phones or reinstalled WhatsApp. This is because in many parts of the world, people frequently change devices and Sim cards. In these situations, we want to make sure people’s messages are delivered, not lost in transit.

He’s technically correct. This is not a backdoor. This really isn’t even a flaw. It’s a design decision that put usability ahead of security in this particular instance. Moxie Marlinspike, creator of Signal and the code base underlying WhatsApp’s encryption, said as much:

Under normal circumstances, when communicating with a contact who has recently changed devices or reinstalled WhatsApp, it might be possible to send a message before the sending client discovers that the receiving client has new keys. The recipient’s device immediately responds, and asks the sender to reencrypt the message with the recipient’s new identity key pair. The sender displays the “safety number has changed” notification, reencrypts the message, and delivers it.

The WhatsApp clients have been carefully designed so that they will not re-encrypt messages that have already been delivered. Once the sending client displays a “double check mark,” it can no longer be asked to re-send that message. This prevents anyone who compromises the server from being able to selectively target previously delivered messages for re-encryption.

The fact that WhatsApp handles key changes is not a “backdoor,” it is how cryptography works. Any attempt to intercept messages in transmit by the server is detectable by the sender, just like with Signal, PGP, or any other end-to-end encrypted communication system.

The only question it might be reasonable to ask is whether these safety number change notifications should be “blocking” or “non-blocking.” In other words, when a contact’s key changes, should WhatsApp require the user to manually verify the new key before continuing, or should WhatsApp display an advisory notification and continue without blocking the user.

Given the size and scope of WhatsApp’s user base, we feel that their choice to display a non-blocking notification is appropriate. It provides transparent and cryptographically guaranteed confidence in the privacy of a user’s communication, along with a simple user experience. The choice to make these notifications “blocking” would in some ways make things worse. That would leak information to the server about who has enabled safety number change notifications and who hasn’t, effectively telling the server who it could MITM transparently and who it couldn’t; something that WhatsApp considered very carefully.

How serious this is depends on your threat model. If you are worried about the US government — or any other government that can pressure Facebook — snooping on your messages, then this is a small vulnerability. If not, then it’s nothing to worry about.

Slashdot thread. Hacker News thread. BoingBoing post. More here.

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Is WhatsApp Hacked?

Forbes is reporting that the Israeli cyberweapons arms manufacturer Wintego has a man-in-the-middle exploit against WhatsApp.

It’s a weird story. I’m not sure how they do it, but something doesn’t sound right.

Another possibility is that CatchApp is malware thrust onto a device over Wi-Fi that specifically targets WhatsApp. But it’s almost certain the product cannot crack the latest standard of WhatsApp cryptography, said Matthew Green, a cryptography expert and assistant professor at the Johns Hopkins Information Security Institute. Green, who has been impressed by the quality of the Signal code, added: “They would have to defeat both the encryption to and from the server and the end-to-end Signal encryption. That does not seem feasible at all, even with a Wi-Fi access point.

“I would bet mundanely the password stuff is just plain phishing. You go to some site, it asks for your Google account, you type it in without looking closely at the address bar.

“But the WhatsApp stuff manifestly should not be vulnerable like that. Interesting.”

Neither WhatsApp nor the crypto whizz behind Signal, Moxie Marlinspike, were happy to comment unless more specific details were revealed about the tool’s capability. Either Wintego is embellishing what its real capability is, or it has a set of exploits that the rest of the world doesn’t yet know about.

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