Even iPhones were vulnerable to the surveillance software, which appears to have been used against activists, journalists, and others.
An international group of journalists this month detailed extensive new evidence that spyware made by Israeli company NSO Group was used against activists, business executives, journalists, and lawyers around the world. Even Apple’s iPhone, frequently lauded for its tight security, was found to be “no match” for the surveillance software, leading Johns Hopkins cryptographer Matthew Green to fret that the NSO revelations had led some hacking experts to descend into a posture of “security nihilism.”
Security nihilism is the idea that digital attacks have grown so sophisticated that there’s nothing to be done to prevent them from happening or to blunt their impact. That sort of conclusion would be a mistake. For one thing, it plays into the hands of malicious hackers, who would love nothing more than for targets to stop trying to defend themselves. It’s also mistaken factually: You can defend yourself against NSO’s spyware — for example, by following operational security techniques like not clicking unknown links, practicing device compartmentalization (such as using separate devices for separate apps), and having a virtual private network, or VPN, on mobile devices. Such techniques are effective against any number of digital attacks and thus useful even if NSO Group turns out to be correct in its claim that the purported evidence against the company is not valid.
There may be no such thing as perfect security, as one classic adage in the field states, but that’s no excuse for passivity. Here, then, are practical steps you can take to reduce your “attack surface” and protect yourself against spyware like NSO’s.
Pegasus Offers “Unlimited Access to Target’s Mobile Devices”
The recent revelations concern a specific NSO spyware product known as Pegasus. They follow extensive prior studies of the company’s software from entities like the Citizen Lab, Amnesty International, Article 19, R3D, and SocialTIC. Here’s what we know about Pegasus specifically.
The software’s capabilities were outlined in what appears to be a promotional brochure from NSO Group dating to 2014 or earlier and made available when WikiLeaks published a trove of emails related to a different spyware firm, Italy’s Hacking Team. The brochure’s authenticity cannot be confirmed, and NSO has said it is not commenting further on Pegasus. But the document markets Pegasus aggressively, saying it provides “unlimited access to target’s mobile devices” and allows clients to “remotely and covertly collect information about your target’s relationships, location, phone calls, plans and activities — whenever and wherever they are.” The brochure also states the Pegasus can:
- Monitor voice and VoIP calls in real-time.
- Siphon contacts, passwords, files, and encrypted content from the phone.
- Operate as an “environmental wiretap,” listening through the microphone.
- Monitor communications through apps like WhatsApp, Facebook, Skype, Blackberry Messenger, and Viber.
- Track the phone’s location via GPS.
For all the hype, Pegasus is, however, just a glorified version of an old type of malware known as a Remote Access Trojan, or RAT: a program that allows an unauthorized party full access over a target device. In other words, while Pegasus may be potent, the security community knows well how to defend against this type of threat.
Let’s look at the different ways Pegasus can potentially infect phones — its various “agent installation vectors,” in the brochure’s own vernacular — and how to defend against each one.
Dodging Social Engineering Clickbait
There are numerous examples in reports of Pegasus attacks of journalists and human rights defenders receiving SMS and WhatsApp bait messages enjoining them to click malicious links. The links download spyware that lodges into devices through security holes in browsers and operating systems. This attack vector is called an Enhanced Social Engineer Message, or ESEM, in the leaked brochure. It states that “the chances that the target will click the link are totally dependent on the level of content credibility. The Pegasus solution provides a wide range of tools to compose a tailored and innocent message to lure the target to open the message.”“The chances that the target will click the link are totally dependent on the level of content credibility.”
As the Committee to Protect Journalists has detailed, ESEM bait messages linked to Pegasus fall into various categories. Some claim to be from established organizations like banks, embassies, news agencies, or parcel delivery services. Others relate to personal matters, like work or alleged evidence of infidelity, or claim that the targeted person is facing some immediate security risk.
Future ESEM attacks may use different types of bait messages, which is why it’s important to treat any correspondence that tries to convince you to perform a digital action with caution. Here are some examples of what that means in practice:
- If you receive a message with a link, particularly if it includes a sense of urgency (stating a package is about to arrive or that your credit card is going to be charged), avoid the impulse to immediately click on it.
- If you trust the linked site, type out the link’s web address manually.
- If going to a website you frequently visit, save that website in a bookmark folder and only access the site from the link in your folder.
- If you decide you’re going to click a link rather than typing it out or visiting the site via bookmark, at least scrutinize the link to confirm that it is pointing to a website you are familiar with. And remember that it’s possible you will still be fooled: Some phishing links use similar-looking letters from a non-English character set, in what is known as a homograph attack. For example, a Cyrillic “О” might be used to mimic the usual Latin “O” we see in English.
- If the link appears to be a shortened URL, use a URL expander service such as URL Expander or ExpandURL to reveal the actual, long link it points to before clicking.
- Before you click a link apparently sent by someone you know, confirm that the person really did send it; their account may have been hacked or their phone number spoofed. Confirm with them using a different communication channel from the one on which you received the message. For instance, if the link came via a text or email message, give the sender a call. This is known as out-of-band verification or authentication.
- Practice device compartmentalization, using a secondary device without any sensitive information on it to open untrusted links. Keep in mind that if the secondary device is infected, it may still be used to monitor you via the microphone or camera, so keep it in a Faraday bag when not in use — or at least away from where you have sensitive conversations (a good idea even if it’s in a Faraday bag).
- Use nondefault browsers. According to a section titled “Installation Failure” in the leaked Pegasus brochure, installation may fail if the target is running an unsupported browser and in particular a browser other than “the default browser of the device.” But the document is now several years old, and it is possible that Pegasus today supports all kinds of browsers.
- If there is ever any doubt about a given link, the safest operational security measure is to avoid opening the link.
Thwarting Network Injection Attacks
Another way Pegasus infected devices in multiple cases was by intercepting a phone’s network traffic using what’s known as a man-in-the-middle, or MITM, attack, in which Pegasus intercepted unencrypted network traffic, like HTTP web requests, and redirected it toward malicious payloads. Pulling this off entailed either tricking the phone into connecting to a rogue portable device which pretends to be a cell tower nearby or gaining access to the target’s cellular carrier (plausible if the target is in a repressive regime where the government provides telecommunication services). This attack worked even if the phone was in mobile data-only mode, and not connected to Wi-Fi.
When Maati Monjib, the co-founder of the Freedom Now NGO and the Moroccan Association for Investigative Journalism, opened the iPhone Safari browser and typed yahoo.fr, Safari first tried going to http://yahoo.fr. Normally this would have redirected to https://fr.yahoo.com, an encrypted connection. But since Monjib’s connection was being intercepted, it instead redirected to a malicious third-party site which ultimately hacked his phone.Typing just the website domain into a browser opens you to attacks, because your browser will attempt an unencrypted connection to the site.
Typing just the website domain (such as yahoo.fr) into a browser address bar without specifying a protocol (such as https://) opens the possibility for MITM attacks, because your browser by default will attempt an unencrypted HTTP connection to the site. Usually, you reach the genuine site, which immediately redirects you to a safe HTTPS connection. But if someone is tracking to hack your device, that first HTTP connection is enough of an opening to hijack your connection.
Some websites protect against this using a complicated security feature known as HTTP Strict Transport Security, which prevents your browser from ever making an unencrypted request to them, but you can’t always count on this, even for some websites that implement it correctly.
Here are some things you can do to prevent these kinds of attacks:
- Always type out https:// when going to websites.
- Bookmark secure (HTTPS) URLs for your favorite sites, and use those instead of typing the domain name directly.
- Alternately, use a VPN on both your desktop and mobile devices. A VPN tunnels all connections securely to the VPN server, which then accesses websites on your behalf and relays them back to you. This means that an attacker monitoring your network will likely not be able to perform a successful MITM attack as your connection is encrypted to the VPN — even if you type a domain directly into your browser without the “https://” part.
Unlike infection attempts which require that the target perform some action like clicking a link or opening an attachment, zero-click exploits are so called because they require no interaction from the target. All that is required is for the targeted person to have a particular vulnerable app or operating system installed. Amnesty International’s forensic report on the recently revealed Pegasus evidence states that some infections were transmitted through zero-click attacks leveraging the Apple Music and iMessage apps.Your device should have the bare minimum of apps that you need.
This is not the first time NSO Group’s tools have been linked to zero-click attacks. A 2017 complaint against Panama’s former President Ricardo Martinelli states that journalists, political figures, union activists, and civic association leaders were targeted with Pegasus and rogue push notifications delivered to their devices, while in 2019 WhatsApp and Facebook filed a complaint claiming NSO Group developed malware capable of exploiting a zero-click vulnerability in WhatsApp.
As zero-click vulnerabilities by definition do not require any user interaction, they are the hardest to defend against. But users can reduce their chances of succumbing to these exploits by reducing what is known as their “attack surface” and by practicing device compartmentalization. Reducing your attack surface simply means minimizing the possible ways that your device may be infected. Device compartmentalization means spreading your data and apps across multiple devices.
Specifically, users can:
- Reduce the number of apps on your phone. The fewer unlocked doors your home has, the fewer opportunities a burglar has to enter; similarly, fewer apps means fewer virtual doors on your phone for an adversary to exploit. Your device should have the bare minimum apps that you need to perform day-to-day function. There are some apps you cannot remove, such as iMessage; in those cases you can often disable them, though doing so will also make text messages no longer work on your iPhone.
- Regularly audit your installed apps (and their permissions), and remove any that you no longer need. It is safer to remove a seldom-used app and download it again when you actually need it than to let it remain on your phone.
- Regularly update both your phone’s operating system and individual apps, since updates close vulnerabilities, sometimes even unintentionally.
- Compartmentalize your remaining apps. If a phone only has WhatsApp installed and is compromised, the hacker will get WhatsApp data, but not other sensitive information like email, calendar, photos, or Signal messages.
- Even a compartmentalized phone can still be used as a wiretap and a tracking device, so keep devices physically compartmentalized — that is, leave them in another room, ideally in a tamper bag.
A final way an attacker can infect your phone is by physically interacting with it. According to the brochure, “when physical access to the device is an option, the Pegasus agent can be manually injected and installed in less than five minutes” — though it is unclear if the phone needs to be unlocked or if attackers are able to infect even a PIN-protected phone.
There seem to be no known cases of physically launched Pegasus attacks, though such exploits may be difficult to spot and distinguish from online attacks. Here’s how you can mitigate them:
- Always maintain a line of sight to your devices. Losing sight of your devices opens the possibility of physical compromise. Obviously there is a difference between a customs agent taking your phone at the airport versus you leaving your laptop behind in a room in your residence when you go to the bathroom, but all involve some risk, and you will have to calibrate your own risk tolerance.
- Put your device in a tamper bag when it needs to be left unattended, particularly in riskier locations like hotel rooms. This will not prevent the device from being manipulated but will at the least provide a ready alert that the device has been taken out of the bag and might have been tampered with, at which point the device should no longer be used.
- Use burner phones and other compartmented devices when entering potentially hostile environments such as government buildings, including embassies and consulates, or when going through border checkpoints.
- Use Amnesty International’s Mobile Verification Toolkit if you suspect your phone is infected with Pegasus.
- Regularly back up important files.
- And finally, there’s no harm in regularly resetting your phone.
Although Pegasus is a sophisticated piece of spyware, there are tangible steps you can take to minimize the chance that your devices will be infected. There’s no foolproof method to eliminate your risk entirely, but there are definitely things you can do to lower that risk, and there’s certainly no need to resort to the defeatist view that we’re “no match” for Pegasus.
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