Are you using Zoom yet? It seems that everyone in America who’s been forced to work, or do schoolwork, from home during the coronavirus lockdown is using the video-conferencing platform for meetings, classes and even social gatherings.
There are good reasons Zoom has taken off and other platforms haven’t. Zoom is easy to set up, easy to use and lets up to 100 people join a meeting for free. It just works.
But there’s a downside. Zoom’s ease of use makes it easy for troublemakers to “bomb” open Zoom meetings, and for hackers to inject malware into a machine running Zoom.
The backlash has already begun. As of April 6, New York City public schools were moving to ban Zoom meetings, and other school systems were reported to be doing the same. (We disagree with that decision, because we think Zoom is safe to use for meetings that aren’t highly sensitive.)
Given the soaring usage of the Zoom platform during the coronavirus lockdown, and the near-doubling of its stock price since the beginning of February, Zoom has come under intense scrutiny from security professionals and privacy advocates. And boy, have they found stuff.
Zoom pledges to fix flaws
In a blog post April 1, Zoom CEO and founder Eric S. Yuan acknowledged Zoom’s growing pains and pledged that all regular development of the Zoom platform would be put on hold while the company worked to fix security and privacy issues.
“We recognize that we have fallen short of the community’s — and our own — privacy and security expectations,” Yuan wrote, explaining that Zoom was developed for large businesses with in-house IT staffers who could set up and run the software.
“We now have a much broader set of users who are utilizing our product in a myriad of unexpected ways, presenting us with challenges we did not anticipate when the platform was conceived,” he said. “These new, mostly consumer use cases have helped us uncover unforeseen issues with our platform. Dedicated journalists and security researchers have also helped to identify pre-existing ones.”
To deal with these issues, Yuan wrote, Zoom would be “enacting a feature freeze, effectively immediately, and shifting all our engineering resources to focus on our biggest trust, safety, and privacy issues.”
Among other things, Zoom would also be “conducting a comprehensive review with third-party experts and representative users to understand and ensure the security of all of our new consumer use cases.”
Zoom is still safe to use in most cases
Does all this mean that Zoom is unsafe to use? No.
You just need to be aware that the Zoom software creates a huge “attack surface,” as security professionals like to say, and that hackers are going to try to come at it every way they can. They’re already registering lots of Zoom-related phony domains and developing Zoom-themed malware.
The upside is that if lots of flaws in Zoom are found now and fixed soon, then Zoom will be the better — and safer — for it.
“Zoom will soon be the most secure conferencing tool out there,” wrote tech journalist Kim Zetter on Twitter April 1. “But too bad they didn’t save themselves some grief and engage in some security assessments of their own to avoid this trial by fire.”
Contrarian view: Zoom will soon be the most secure conferencing tool out there. (But too bad they didn’t save themselves some grief and engage in some security assessments of their own to avoid this trial by fire) https://t.co/8BLeNJiV7VApril 1, 2020
Unless you’re discussing state or corporate secrets, or disclosing personal health information to a patient, Zoom should be fine to use. Just require that meeting participants sign in with a password.
Everything that’s gone wrong with Zoom lately
To keep ourselves (and you) sane, we’re putting the most recent Zoom privacy and security issues up top and separating the problems into those that are open or unresolved, those that have been resolved and those that don’t fit into either category.
The latest: Monday, April 6
Zoom installer bundled with malware
Researchers at Trend Micro discovered a version of the Zoom installer that has been bundled with cryptocurrency-mining malware, i.e. a coin-miner.
The Zoom installer will put Zoom version 22.214.171.124 on your Windows PC, but it comes with a coin-miner that Trend Micro has given the catchy name Trojan.Win32.MOOZ.THCCABO. (By the way, the latest Zoom client software for Windows is up to version 4.6.9, and you should get it only from here.)
The coin-miner will ramp up your PC’s central processor unit, and its graphics card if there is one, to solve mathematical problems in order to generate new units of cryptocurrency. You’ll notice this if you fans suddenly speed up or if Windows Task Manager (hit Ctrl + Shift + Esc) shows unexpectedly heavy CPU/GPU use.
To avoid getting hit with this malware, make sure you’re running one of the best antivirus programs, and don’t click on any links in emails, social media posts or pop-up messages that promise to install Zoom on your machine.
STATUS: Open, but this isn’t Zoom’s problem to fix. It can’t stop other people from copying and redistributing its installation software.
Zoom encryption isn’t what it’s cracked up to be
Not only does Zoom mislead users about its “end-to-end encryption” (see further down), but its seems to be flat-out, um, not telling the truth about the quality of its encryption algorithm.
Zoom says it use AES-256 encryption to encode video and audio data traveling between Zoom servers and Zoom clients (i.e., you and me). But researchers at the Citizen Lab at the University of Toronto, in a report posted April 3, found that Zoom actually uses the somewhat weaker AES-128 algorithm.
Even worse, Zoom uses an in-house implementation of encryption algorithm that preserves patterns from the original file. It’s as if someone drew a red circle on a gray wall, and then a censor painted over the red circle with a while circle. You’re not seeing the original message, but the shape is still there.
“We discourage the use of Zoom at this time for use cases that require strong privacy and confidentiality,” the Citizen Lab report says, such as “governments worried about espionage, businesses concerned about cybercrime and industrial espionage, healthcare providers handling sensitive patient information” and “activists, lawyers, and journalists working on sensitive topics.”
STATUS: Unresolved. In a blog post April 3, Zoom CEO Eric S. Yuan acknowledged the encryption issue but said only that “we recognize that we can do better with our encryption design” and “we expect to have more to share on this front in the coming days.”
Zoom cryptographic keys issued by Chinese servers
Those AES128 encryption keys are issued to Zoom clients by Zoom servers, which is all well and good, except that the Citizen Lab found several Zoom servers in China issuing keys to Zoom users even when all participants in a meeting were in North America.
Since Zoom servers can decrypt Zoom meetings, and Chinese authorities can compel operators of Chinese servers to hand over data, the implication is that the Chinese government might be able to see your Zoom meetings.
That’s got to be bad news for the British government, which has held at least one Cabinet meeting over Zoom.
STATUS: Apparently fixed. In a blog post April 3, Zoom CEO Eric S. Yuan responded to the Citizen Lab report by saying that “it is possible certain meetings were allowed to connect to systems in China, where they should not have been able to connect. We have since corrected this.”
Security flaw with Zoom meeting waiting rooms
Zoom advises meeting hosts to set up “waiting rooms” to avoid “Zoom bombing.” A waiting room essentially keeps participants on hold until a host lets them in, either all at once or one at a time.
The Citizen Lab said it found a serious security issue with Zoom waiting rooms, and advised hosts and participants to not use them for now. The Citizen Lab is not disclosing the details yet, but has told Zoom of the flaw.
“We advise Zoom users who desire confidentiality to not use Zoom Waiting Rooms,” the Citizen Lab said in its report. “Instead, we encourage users to use Zoom’s password feature.”
STATUS: Unknown. Yuan did not mention this issue in his April 3 blog post.
Zoom software can be easily corrupted
Good software has built-in anti-tampering mechanisms to make sure that applications don’t run code that’s been altered by a third party.
Zoom has such anti-tampering mechanisms in place, which is good. But those anti-tampering mechanisms themselves are not protected from tampering, said a British computer student who calls himself “Lloyd” in a blog post April 3.
Needless to say, that’s bad. Lloyd showed how Zoom’s anti-tampering mechanism can easily be disabled, or even replaced with a malicious version that hijacks the application.
If you’re reading this with a working knowledge of how Windows software works, this is a pretty damning passage: “This DLL can be trivially unloaded, rendering the anti-tampering mechanism null and void. The DLL is not pinned, meaning an attacker from a 3rd party process could simply inject a remote thread.”
In other words, malware already present on a computer could use Zoom’s own anti-tampering mechanism to tamper with Zoom. Criminals could also create fully working versions of Zoom that have been altered to perform malicious acts.
Anyone can “bomb” a public Zoom meeting if they know the meeting number, and then use the file-share photo to post shocking images, or make annoying sounds in the audio. The FBI even warned about it a few days ago.
The host of the Zoom meeting can mute or even kick out troublemakers, but they can come right back with new user IDs. The best way to avoid Zoom bombing is to not share Zoom meeting numbers with anyone but the intended participants. You can also require participants to use a password to log into the meeting.
On April 3, the U.S. Attorney’s Office for the Eastern District of Michigan said that “anyone who hacks into a teleconference can be charged with state or federal crimes.” It’s not clear whether that applies only to eastern Michigan.
STATUS: There are easy ways to avoid Zoom bombing, which we go through here.
Leaks of email addresses and profile photos
Zoom automatically puts everyone sharing the same email domain into a “company” folder where they can see each other’s information.
Exceptions are made for people using large webmail clients such as Gmail, Yahoo, Hotmail or Outlook.com, but not apparently for smaller webmail providers that Zoom might not know about.
Several Dutch Zoom users who use ISP-provided email addresses suddenly found that they were in the same “company” with dozens of strangers — and could see their email addresses, user names and user photos.
Sharing of personal data with advertisers
STATUS: Unknown. We don’t know the details of Zoom’s business dealings with third-party advertisers.
You can ‘war drive’ to find open Zoom meetings
You can find open Zoom meetings by rapidly cycling through possible Zoom meeting IDs, a security researcher told independent security blogger Brian Krebs.
The researcher got past Zoom’s meeting-scan blocker by running queries through Tor, which randomized his IP address. It’s a variation on “war driving” by randomly dialing telephone numbers to find open modems in the dial-up days.
The researcher told Krebs that he could find about 100 open Zoom meetings every hour with the tool, and that “having a password enabled on the [Zoom] meeting is the only thing that defeats it.”
Zoom meeting chats don’t stay private
Two Twitter users pointed out that if you’re in a Zoom meeting and use a private window in the meeting’s chat app to communicate privately with another person in the meeting, that conversation will be visible in the end-of-meeting transcript the host receives.
Windows password stealing
Zoom meetings have side chats in which participants can sent text-based messages and post web links.
But according to Twitter user @_g0dmode and Anglo-American cybersecurity training firm Hacker House, Zoom until the end of March made no distinction between regular web addresses and a different kind of remote networking link called a Universal Naming Convention (UNC) path. That left Zoom chats vulnerable to attack.
If a malicious Zoom bomber slipped a UNC path to a remote server that he controlled into a Zoom meeting chat, an unwitting participant could click on it.
The participant’s Windows computer would then try to reach out to the hacker’s remote server specified in the path and automatically try to log into it using the user’s Windows username and password.
The hacker could capture the password “hash” and decrypt it, giving him access to the Zoom user’s Windows account.
STATUS: Yuan’s blog post says Zoom has now fixed this problem.
Windows malware injection
Mohamed A. Baset of security firm Seekurity said on Twitter that the same filepath flaw also would let a hacker insert a UNC path to a remote executable file into a Zoom meeting chatroom.
If a Zoom user running Windows clicked on it, a video posted by Baset showed, the user’s computer would try to load and run the software. The victim would be prompted to authorize the software to run, which will stop some hacking attempts but not all.
STATUS: If the UNC filepath issue is fixed, then this should be as well.
iOS profile sharing
Until late March, Zoom sent iOS user profiles to Facebook as part of the “log in with Facebook” feature in the iPhone and iPad Zoom apps. After Vice News exposed the practice, Zoom said it hadn’t been aware of the profile-sharing and updated the iOS apps to fix this.
Malware-like behavior on Macs
We learned last summer that Zoom used hacker-like methods to bypass normal macOS security precautions. We thought that problem had been fixed then, along with the security flaw it created.
But a series of tweets March 30 from security researcher Felix Seele, who noticed that Zoom installed itself on his Mac without the usual user authorizations, revealed that there was still an issue.
Ever wondered how the @zoom_us macOS installer does it’s job without you ever clicking install? Turns out they (ab)use preinstallation scripts, manually unpack the app using a bundled 7zip and install it to /Applications if the current user is in the admin group (no root needed). pic.twitter.com/qgQ1XdU11MMarch 30, 2020
“They (ab)use preinstallation scripts, manually unpack the app using a bundled 7zip and install it to /Applications if the current user is in the admin group (no root needed),” Seele wrote.
“The application is installed without the user giving his final consent and a highly misleading prompt is used to gain root privileges. The same tricks that are being used by macOS malware.” (Seele elaborated in a more user-friendly blog post here.)
Zoom founder and CEO Eric S. Yuan tweeted a friendly response.
“To join a meeting from a Mac is not easy, that is why this method is used by Zoom and others,” Yuan wrote. “Your point is well taken and we will continue to improve.”
UPDATE: In a new tweet April 2, Seele said Zoom had released a new version of the Zoom client for macOS that “completely removes the questionable ‘preinstall’-technique and the faked password prompt.”
“I must say that I am impressed. That was a swift and comprehensive reaction. Good work, @zoom_us!” Seele added.
Zoom just released an update for the macOS installer which completely removes the questionable “preinstall”-technique and the faked password prompt.I must say that I am impressed. That was a swift and comprehensive reaction. Good work, @zoom_us! pic.twitter.com/vau556TyAaApril 2, 2020
A backdoor for Mac malware
Other people could use Zoom’s dodgy Mac installation methods, renowned Mac hacker Patrick Wardle said in a blog post March 30.
Wardle demonstrated how a local attacker — such as a malicious human or already-installed malware — could use Zoom’s formerly magical powers of unauthorized installation to “escalate privileges” and gain total control over the machine without knowing the administrator password.
Wardle also showed that a malicious script installed into the Zoom Mac client could give any piece of malware Zoom’s webcam and microphone privileges, which do not prompt the user for authorization and could turn any Mac with Zoom installed into a potential spying device.
“This affords malware the ability to record all Zoom meetings, or simply spawn Zoom in the background to access the mic and webcam at arbitrary times,” Wardle wrote.
STATUS: Yuan’s blog post says Zoom has fixed these flaws.
Phony end-to-end encryption
Zoom claims its meetings use “end-to-end encryption” if every participant calls in from a computer or a Zoom mobile app instead of over the phone. But under pressure from The Intercept, a Zoom representative admitted that Zoom’s definitions of “end-to-end” and “endpoint” are not the same as everyone else’s.
“When we use the phrase ‘End to End’,” a Zoom spokeperson told The Intercept, “it is in reference to the connection being encrypted from Zoom end point to Zoom end point.”
Sound good, but the spokesperson clarified that he counted a Zoom server as an endpoint.
Every other company considers an endpoint to be a user device — a desktop, laptop, smartphone or tablet — but not a server. And every other company takes “end-to-end encryption” to mean that servers that relay messages from one endpoint to another can’t decrypt the messages.
When you send an Apple Message from your iPhone to another iPhone user, Apple’s servers help the message get from one place to another, but they can’t read the content.
Not so with Zoom. It can see whatever is going on in its meetings, and sometimes it may have to in order to make sure everything works properly. Just don’t believe the implication that it can’t.
UPDATE: In a blog post April 1, Zoom Chief Product Officer Oded Gal wrote that “we want to start by apologizing for the confusion we have caused by incorrectly suggesting that Zoom meetings were capable of using end-to-end encryption. “
“We recognize that there is a discrepancy between the commonly accepted definition of end-to-end encryption and how we were using it,” he wrote.
Gal assured users that all data sent and received by Zoom client applications (but not regular phone lines, business conferencing systems or, presumably, browser interfaces) is indeed encrypted and that Zoom servers or staffers “do not decrypt it at any point before it reaches the receiving clients.”
However, Gal added, “Zoom currently maintains the key management system for these systems in the cloud” but has “implemented robust and validated internal controls to prevent unauthorized access to any content that users share during meetings.”
The implication is that Zoom doesn’t decrypt user transmissions by choice. But because it holds the encryption keys, Zoom could if it had to, such as if it were presented with a warrant or a U.S. National Security Letter (essentially a secret warrant).
For those worried about government snooping, Gal wrote that “Zoom has never built a mechanism to decrypt live meetings for lawful intercept purposes, nor do we have means to insert our employees or others into meetings without being reflected in the participant list.”
He added that companies and other enterprises would soon be able to handle their own encryption process.
“A solution will be available later this year to allow organizations to leverage Zoom’s cloud infrastructure but host the key management system within their environment.”
STATUS: This is an issue of misleading advertising rather than an actual software flaw. We hope Zoom stops using the term “end-to-end encryption” incorrectly, but just keep in mind that you may not be getting the real thing with Zoom.
Zoom meeting recordings can be found online
Privacy researcher Patrick Jackson noticed that Zoom meeting recordings saved to the host’s computer generally get a certain type of file name.
So he searched unprotected cloud servers to see if anyone had uploaded Zoom recordings and found more than 15,000 unprotected examples, according to The Washington Post. Jackson also found some recorded Zoom meetings on YouTube and Vimeo.
This isn’t really Zoom’s fault. It’s up to the host to decide whether to record a meeting, and Zoom gives paying customers the option to store recordings on Zoom’s own servers. It’s also up to the host to decide to change the recording’s file name.
If you host a Zoom meeting and decide to record it, then make sure you change the default file name after you’re done.
STATUS: This is not really Zoom’s problem, to be honest.