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Router Security

This report is six months old, and I don’t know anything about the organization that produced it, but it has some alarming data about router security.

Conclusion: Our analysis showed that Linux is the most used OS running on more than 90% of the devices. However, many routers are powered by very old versions of Linux. Most devices are still powered with a 2.6 Linux kernel, which is no longer maintained for many years. This leads to a high number of critical and high severity CVEs affecting these devices.

Since Linux is the most used OS, exploit mitigation techniques could be enabled very easily. Anyhow, they are used quite rarely by most vendors except the NX feature.

A published private key provides no security at all. Nonetheless, all but one vendor spread several private keys in almost all firmware images.

Mirai used hard-coded login credentials to infect thousands of embedded devices in the last years. However, hard-coded credentials can be found in many of the devices and some of them are well known or at least easy crackable.

However, we can tell for sure that the vendors prioritize security differently. AVM does better job than the other vendors regarding most aspects. ASUS and Netgear do a better job in some aspects than D-Link, Linksys, TP-Link and Zyxel.

Additionally, our evaluation showed that large scale automated security analysis of embedded devices is possible today utilizing just open source software. To sum it up, our analysis shows that there is no router without flaws and there is no vendor who does a perfect job regarding all security aspects. Much more effort is needed to make home routers as secure as current desktop of server systems.

One comment on the report:

One-third ship with Linux kernel version 2.6.36 was released in October 2010. You can walk into a store today and buy a brand new router powered by software that’s almost 10 years out of date! This outdated version of the Linux kernel has 233 known security vulnerabilities registered in the Common Vulnerability and Exposures (CVE) database. The average router contains 26 critically-rated security vulnerabilities, according to the study.

We know the reasons for this. Most routers are designed offshore, by third parties, and then private labeled and sold by the vendors you’ve heard of. Engineering teams come together, design and build the router, and then disperse. There’s often no one around to write patches, and most of the time router firmware isn’t even patchable. The way to update your home router is to throw it away and buy a new one.

And this paper demonstrates that even the new ones aren’t likely to be secure.

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Posted on February 19, 2021 at 6:00 AM • View Comments

Browser Tracking Using Favicons

Interesting research on persistent web tracking using favicons. (For those who don’t know, favicons are those tiny icons that appear in browser tabs next to the page name.)

Abstract: The privacy threats of online tracking have garnered considerable attention in recent years from researchers and practitioners alike. This has resulted in users becoming more privacy-cautious and browser vendors gradually adopting countermeasures to mitigate certain forms of cookie-based and cookie-less tracking. Nonetheless, the complexity and feature-rich nature of modern browsers often lead to the deployment of seemingly innocuous functionality that can be readily abused by adversaries. In this paper we introduce a novel tracking mechanism that misuses a simple yet ubiquitous browser feature: favicons. In more detail, a website can track users across browsing sessions by storing a tracking identifier as a set of entries in the browser’s dedicated favicon cache, where each entry corresponds to a specific subdomain. In subsequent user visits the website can reconstruct the identifier by observing which favicons are requested by the browser while the user is automatically and rapidly redirected through a series of subdomains. More importantly, the caching of favicons in modern browsers exhibits several unique characteristics that render this tracking vector particularly powerful, as it is persistent (not affected by users clearing their browser data), non-destructive (reconstructing the identifier in subsequent visits does not alter the existing combination of cached entries), and even crosses the isolation of the incognito mode. We experimentally evaluate several aspects of our attack, and present a series of optimization techniques that render our attack practical. We find that combining our favicon-based tracking technique with immutable browser-fingerprinting attributes that do not change over time allows a website to reconstruct a 32-bit tracking identifier in 2 seconds. Furthermore,our attack works in all major browsers that use a favicon cache, including Chrome and Safari. Due to the severity of our attack we propose changes to browsers’ favicon caching behavior that can prevent this form of tracking, and have disclosed our findings to browser vendors who are currently exploring appropriate mitigation strategies.

Another researcher has implemented this proof of concept:

Strehle has set up a website that demonstrates how easy it is to track a user online using a favicon. He said it’s for research purposes, has released his source code online, and detailed a lengthy explanation of how supercookies work on his website.

The scariest part of the favicon vulnerability is how easily it bypasses traditional methods people use to keep themselves private online. According to Strehle, the supercookie bypasses the “private” mode of Chrome, Safari, Edge, and Firefox. Clearing your cache, surfing behind a VPN, or using an ad-blocker won’t stop a malicious favicon from tracking you.

EDITED TO ADD (3/12): There was an issue about whether this paper was inappropriately disclosed, and it was briefly deleted from the NDSS website. It was later put back with a prefatory note from the NDSS.

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Posted on February 17, 2021 at 6:05 AM • View Comments

Malicious Barcode Scanner App

Interesting story about a barcode scanner app that has been pushing malware on to Android phones. The app is called Barcode Scanner. It’s been around since 2017 and is owned by the Ukrainian company Lavabird Ldt. But a December 2020 update included some new features:

However, a rash of malicious activity was recently traced back to the app. Users began noticing something weird going on with their phones: their default browsers kept getting hijacked and redirected to random advertisements, seemingly out of nowhere.

Generally, when this sort of thing happens it’s because the app was recently sold. That’s not the case here.

It is frightening that with one update an app can turn malicious while going under the radar of Google Play Protect. It is baffling to me that an app developer with a popular app would turn it into malware. Was this the scheme all along, to have an app lie dormant, waiting to strike after it reaches popularity? I guess we will never know.

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Posted on February 16, 2021 at 6:13 AM • View Comments

Deliberately Playing Copyrighted Music to Avoid Being Live-Streamed

Vice is reporting on a new police hack: playing copyrighted music when being filmed by citizens, trying to provoke social media sites into taking the videos down and maybe even banning the filmers:

In a separate part of the video, which Devermont says was filmed later that same afternoon, Devermont approaches [BHPD Sgt. Billy] Fair outside. The interaction plays out almost exactly like it did in the department—when Devermont starts asking questions, Fair turns on the music.

Devermont backs away, and asks him to stop playing music. Fair says “I can’t hear you”—again, despite holding a phone that is blasting tunes.

Later, Fair starts berating Devermont’s livestreaming account, saying “I read the comments [on your account], they talk about how fake you are.” He then holds out his phone, which is still on full blast, and walks toward Devermont, saying “Listen to the music”.

In a statement emailed to VICE News, Beverly Hills PD said that “the playing of music while accepting a complaint or answering questions is not a procedure that has been recommended by Beverly Hills Police command staff,” and that the videos of Fair were “currently under review.”

However, this is not the first time that a Beverly Hills police officer has done this, nor is Fair the only one.

In an archived clip from a livestream shared privately to VICE Media that Devermont has not publicly reposted but he says was taken weeks ago, another officer can be seen quickly swiping through his phone as Devermont approaches. By the time Devermont is close enough to speak to him, the officer’s phone is already blasting “In My Life” by the Beatles—a group whose rightsholders have notoriously sued Apple numerous times. If you want to get someone in trouble for copyright infringement, the Beatles are quite possibly your best bet.

As Devermont asks about the music, the officer points the phone at him, asking, “Do you like it?”

Clever, really, and an illustration of the problem with context-free copyright enforcement.

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Posted on February 15, 2021 at 1:11 PM • View Comments

On Vulnerability-Adjacent Vulnerabilities

At the virtual Enigma Conference, Google’s Project Zero’s Maggie Stone gave a talk about zero-day exploits in the wild. In it, she talked about how often vendors fix vulnerabilities only to have the attackers tweak their exploits to work again. From a MIT Technology Review article:

Soon after they were spotted, the researchers saw one exploit being used in the wild. Microsoft issued a patch and fixed the flaw, sort of. In September 2019, another similar vulnerability was found being exploited by the same hacking group.

More discoveries in November 2019, January 2020, and April 2020 added up to at least five zero-day vulnerabilities being exploited from the same bug class in short order. Microsoft issued multiple security updates: some failed to actually fix the vulnerability being targeted, while others required only slight changes that required just a line or two to change in the hacker’s code to make the exploit work again.

[…]

“What we saw cuts across the industry: Incomplete patches are making it easier for attackers to exploit users with zero-days,” Stone said on Tuesday at the security conference Enigma. “We’re not requiring attackers to come up with all new bug classes, develop brand new exploitation, look at code that has never been researched before. We’re allowing the reuse of lots of different vulnerabilities that we previously knew about.”

[…]

Why aren’t they being fixed? Most of the security teams working at software companies have limited time and resources, she suggests—and if their priorities and incentives are flawed, they only check that they’ve fixed the very specific vulnerability in front of them instead of addressing the bigger problems at the root of many vulnerabilities.

Another article on the talk.

This is an important insight. It’s not enough to patch existing vulnerabilities. We need to make it harder for attackers to find new vulnerabilities to exploit. Closing entire families of vulnerabilities, rather than individual vulnerabilities one at a time, is a good way to do that.

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Posted on February 15, 2021 at 6:14 AM • View Comments

Chinese Supply-Chain Attack on Computer Systems

Bloomberg News has a major story about the Chinese hacking computer motherboards made by Supermicro, Levono, and others. It’s been going on since at least 2008. The US government has known about it for almost as long, and has tried to keep the attack secret:

China’s exploitation of products made by Supermicro, as the U.S. company is known, has been under federal scrutiny for much of the past decade, according to 14 former law enforcement and intelligence officials familiar with the matter. That included an FBI counterintelligence investigation that began around 2012, when agents started monitoring the communications of a small group of Supermicro workers, using warrants obtained under the Foreign Intelligence Surveillance Act, or FISA, according to five of the officials.

There’s lots of detail in the article, and I recommend that you read it through.

This is a follow on, with a lot more detail, to a story Bloomberg reported on in fall 2018. I didn’t believe the story back then, writing:

I don’t think it’s real. Yes, it’s plausible. But first of all, if someone actually surreptitiously put malicious chips onto motherboards en masse, we would have seen a photo of the alleged chip already. And second, there are easier, more effective, and less obvious ways of adding backdoors to networking equipment.

I seem to have been wrong. From the current Bloomberg story:

Mike Quinn, a cybersecurity executive who served in senior roles at Cisco Systems Inc. and Microsoft Corp., said he was briefed about added chips on Supermicro motherboards by officials from the U.S. Air Force. Quinn was working for a company that was a potential bidder for Air Force contracts, and the officials wanted to ensure that any work would not include Supermicro equipment, he said. Bloomberg agreed not to specify when Quinn received the briefing or identify the company he was working for at the time.

“This wasn’t a case of a guy stealing a board and soldering a chip on in his hotel room; it was architected onto the final device,” Quinn said, recalling details provided by Air Force officials. The chip “was blended into the trace on a multilayered board,” he said.

“The attackers knew how that board was designed so it would pass” quality assurance tests, Quinn said.

Supply-chain attacks are the flavor of the moment, it seems. But they’re serious, and very hard to defend against in our deeply international IT industry. (I have repeatedly called this an “insurmountable problem.”) Here’s me in 2018:

Supply-chain security is an incredibly complex problem. US-only design and manufacturing isn’t an option; the tech world is far too internationally interdependent for that. We can’t trust anyone, yet we have no choice but to trust everyone. Our phones, computers, software and cloud systems are touched by citizens of dozens of different countries, any one of whom could subvert them at the demand of their government.

We need some fundamental security research here. I wrote this in 2019:

The other solution is to build a secure system, even though any of its parts can be subverted. This is what the former Deputy Director of National Intelligence Sue Gordon meant in April when she said about 5G, “You have to presume a dirty network.” Or more precisely, can we solve this by building trustworthy systems out of untrustworthy parts?

It sounds ridiculous on its face, but the Internet itself was a solution to a similar problem: a reliable network built out of unreliable parts. This was the result of decades of research. That research continues today, and it’s how we can have highly resilient distributed systems like Google’s network even though none of the individual components are particularly good. It’s also the philosophy behind much of the cybersecurity industry today: systems watching one another, looking for vulnerabilities and signs of attack.

It seems that supply-chain attacks are constantly in the news right now. That’s good. They’ve been a serious problem for a long time, and we need to take the threat seriously. For further reading, I strongly recommend this Atlantic Council report from last summer: “Breaking trust: Shades of crisis across an insecure software supply chain.“

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Posted on February 13, 2021 at 9:41 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.