Entries Tagged "hacking"

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Backdoor in XZ Utils That Almost Happened

Last week, the Internet dodged a major nation-state attack that would have had catastrophic cybersecurity repercussions worldwide. It’s a catastrophe that didn’t happen, so it won’t get much attention—but it should. There’s an important moral to the story of the attack and its discovery: The security of the global Internet depends on countless obscure pieces of software written and maintained by even more obscure unpaid, distractible, and sometimes vulnerable volunteers. It’s an untenable situation, and one that is being exploited by malicious actors. Yet precious little is being done to remedy it.

Programmers dislike doing extra work. If they can find already-written code that does what they want, they’re going to use it rather than recreate the functionality. These code repositories, called libraries, are hosted on sites like GitHub. There are libraries for everything: displaying objects in 3D, spell-checking, performing complex mathematics, managing an e-commerce shopping cart, moving files around the Internet—everything. Libraries are essential to modern programming; they’re the building blocks of complex software. The modularity they provide makes software projects tractable. Everything you use contains dozens of these libraries: some commercial, some open source and freely available. They are essential to the functionality of the finished software. And to its security.

You’ve likely never heard of an open-source library called XZ Utils, but it’s on hundreds of millions of computers. It’s probably on yours. It’s certainly in whatever corporate or organizational network you use. It’s a freely available library that does data compression. It’s important, in the same way that hundreds of other similar obscure libraries are important.

Many open-source libraries, like XZ Utils, are maintained by volunteers. In the case of XZ Utils, it’s one person, named Lasse Collin. He has been in charge of XZ Utils since he wrote it in 2009. And, at least in 2022, he’s had some “longterm mental health issues.” (To be clear, he is not to blame in this story. This is a systems problem.)

Beginning in at least 2021, Collin was personally targeted. We don’t know by whom, but we have account names: Jia Tan, Jigar Kumar, Dennis Ens. They’re not real names. They pressured Collin to transfer control over XZ Utils. In early 2023, they succeeded. Tan spent the year slowly incorporating a backdoor into XZ Utils: disabling systems that might discover his actions, laying the groundwork, and finally adding the complete backdoor earlier this year. On March 25, Hans Jansen—another fake name—tried to push the various Unix systems to upgrade to the new version of XZ Utils.

And everyone was poised to do so. It’s a routine update. In the span of a few weeks, it would have been part of both Debian and Red Hat Linux, which run on the vast majority of servers on the Internet. But on March 29, another unpaid volunteer, Andres Freund—a real person who works for Microsoft but who was doing this in his spare time—noticed something weird about how much processing the new version of XZ Utils was doing. It’s the sort of thing that could be easily overlooked, and even more easily ignored. But for whatever reason, Freund tracked down the weirdness and discovered the backdoor.

It’s a masterful piece of work. It affects the SSH remote login protocol, basically by adding a hidden piece of functionality that requires a specific key to enable. Someone with that key can use the backdoored SSH to upload and execute an arbitrary piece of code on the target machine. SSH runs as root, so that code could have done anything. Let your imagination run wild.

This isn’t something a hacker just whips up. This backdoor is the result of a years-long engineering effort. The ways the code evades detection in source form, how it lies dormant and undetectable until activated, and its immense power and flexibility give credence to the widely held assumption that a major nation-state is behind this.

If it hadn’t been discovered, it probably would have eventually ended up on every computer and server on the Internet. Though it’s unclear whether the backdoor would have affected Windows and macOS, it would have worked on Linux. Remember in 2020, when Russia planted a backdoor into SolarWinds that affected 14,000 networks? That seemed like a lot, but this would have been orders of magnitude more damaging. And again, the catastrophe was averted only because a volunteer stumbled on it. And it was possible in the first place only because the first unpaid volunteer, someone who turned out to be a national security single point of failure, was personally targeted and exploited by a foreign actor.

This is no way to run critical national infrastructure. And yet, here we are. This was an attack on our software supply chain. This attack subverted software dependencies. The SolarWinds attack targeted the update process. Other attacks target system design, development, and deployment. Such attacks are becoming increasingly common and effective, and also are increasingly the weapon of choice of nation-states.

It’s impossible to count how many of these single points of failure are in our computer systems. And there’s no way to know how many of the unpaid and unappreciated maintainers of critical software libraries are vulnerable to pressure. (Again, don’t blame them. Blame the industry that is happy to exploit their unpaid labor.) Or how many more have accidentally created exploitable vulnerabilities. How many other coercion attempts are ongoing? A dozen? A hundred? It seems impossible that the XZ Utils operation was a unique instance.

Solutions are hard. Banning open source won’t work; it’s precisely because XZ Utils is open source that an engineer discovered the problem in time. Banning software libraries won’t work, either; modern software can’t function without them. For years, security engineers have been pushing something called a “software bill of materials”: an ingredients list of sorts so that when one of these packages is compromised, network owners at least know if they’re vulnerable. The industry hates this idea and has been fighting it for years, but perhaps the tide is turning.

The fundamental problem is that tech companies dislike spending extra money even more than programmers dislike doing extra work. If there’s free software out there, they are going to use it—and they’re not going to do much in-house security testing. Easier software development equals lower costs equals more profits. The market economy rewards this sort of insecurity.

We need some sustainable ways to fund open-source projects that become de facto critical infrastructure. Public shaming can help here. The Open Source Security Foundation (OSSF), founded in 2022 after another critical vulnerability in an open-source library—Log4j—was discovered, addresses this problem. The big tech companies pledged $30 million in funding after the critical Log4j supply chain vulnerability, but they never delivered. And they are still happy to make use of all this free labor and free resources, as a recent Microsoft anecdote indicates. The companies benefiting from these freely available libraries need to actually step up, and the government can force them to.

There’s a lot of tech that could be applied to this problem, if corporations were willing to spend the money. Liabilities will help. The Cybersecurity and Infrastructure Security Agency’s (CISA’s) “secure by design” initiative will help, and CISA is finally partnering with OSSF on this problem. Certainly the security of these libraries needs to be part of any broad government cybersecurity initiative.

We got extraordinarily lucky this time, but maybe we can learn from the catastrophe that didn’t happen. Like the power grid, communications network, and transportation systems, the software supply chain is critical infrastructure, part of national security, and vulnerable to foreign attack. The US government needs to recognize this as a national security problem and start treating it as such.

This essay originally appeared in Lawfare.

Posted on April 11, 2024 at 7:01 AM • View Comments

US Cyber Safety Review Board on the 2023 Microsoft Exchange Hack

The US Cyber Safety Review Board released a report on the summer 2023 hack of Microsoft Exchange by China. It was a serious attack by the Chinese government that accessed the emails of senior US government officials.

From the executive summary:

The Board finds that this intrusion was preventable and should never have occurred. The Board also concludes that Microsoft’s security culture was inadequate and requires an overhaul, particularly in light of the company’s centrality in the technology ecosystem and the level of trust customers place in the company to protect their data and operations. The Board reaches this conclusion based on:

  1. the cascade of Microsoft’s avoidable errors that allowed this intrusion to succeed;
  2. Microsoft’s failure to detect the compromise of its cryptographic crown jewels on its own, relying instead on a customer to reach out to identify anomalies the customer had observed;
  3. the Board’s assessment of security practices at other cloud service providers, which maintained security controls that Microsoft did not;
  4. Microsoft’s failure to detect a compromise of an employee’s laptop from a recently acquired company prior to allowing it to connect to Microsoft’s corporate network in 2021;
  5. Microsoft’s decision not to correct, in a timely manner, its inaccurate public statements about this incident, including a corporate statement that Microsoft believed it had determined the likely root cause of the intrusion when in fact, it still has not; even though Microsoft acknowledged to the Board in November 2023 that its September 6, 2023 blog post about the root cause was inaccurate, it did not update that post until March 12, 2024, as the Board was concluding its review and only after the Board’s repeated questioning about Microsoft’s plans to issue a correction;
  6. the Board’s observation of a separate incident, disclosed by Microsoft in January 2024, the investigation of which was not in the purview of the Board’s review, which revealed a compromise that allowed a different nation-state actor to access highly-sensitive Microsoft corporate email accounts, source code repositories, and internal systems; and
  7. how Microsoft’s ubiquitous and critical products, which underpin essential services that support national security, the foundations of our economy, and public health and safety, require the company to demonstrate the highest standards of security, accountability, and transparency.

The report includes a bunch of recommendations. It’s worth reading in its entirety.

The board was established in early 2022, modeled in spirit after the National Transportation Safety Board. This is their third report.

Here are a few news articles.

EDITED TO ADD (4/15): Adam Shostack has some good commentary.

Posted on April 9, 2024 at 9:56 AM • View Comments

XZ Utils Backdoor

The cybersecurity world got really lucky last week. An intentionally placed backdoor in XZ Utils, an open-source compression utility, was pretty much accidentally discovered by a Microsoft engineer—weeks before it would have been incorporated into both Debian and Red Hat Linux. From ArsTehnica:

Malicious code added to XZ Utils versions 5.6.0 and 5.6.1 modified the way the software functions. The backdoor manipulated sshd, the executable file used to make remote SSH connections. Anyone in possession of a predetermined encryption key could stash any code of their choice in an SSH login certificate, upload it, and execute it on the backdoored device. No one has actually seen code uploaded, so it’s not known what code the attacker planned to run. In theory, the code could allow for just about anything, including stealing encryption keys or installing malware.

It was an incredibly complex backdoor. Installing it was a multi-year process that seems to have involved social engineering the lone unpaid engineer in charge of the utility. More from ArsTechnica:

In 2021, someone with the username JiaT75 made their first known commit to an open source project. In retrospect, the change to the libarchive project is suspicious, because it replaced the safe_fprint function with a variant that has long been recognized as less secure. No one noticed at the time.

The following year, JiaT75 submitted a patch over the XZ Utils mailing list, and, almost immediately, a never-before-seen participant named Jigar Kumar joined the discussion and argued that Lasse Collin, the longtime maintainer of XZ Utils, hadn’t been updating the software often or fast enough. Kumar, with the support of Dennis Ens and several other people who had never had a presence on the list, pressured Collin to bring on an additional developer to maintain the project.

There’s a lot more. The sophistication of both the exploit and the process to get it into the software project scream nation-state operation. It’s reminiscent of Solar Winds, although (1) it would have been much, much worse, and (2) we got really, really lucky.

I simply don’t believe this was the only attempt to slip a backdoor into a critical piece of Internet software, either closed source or open source. Given how lucky we were to detect this one, I believe this kind of operation has been successful in the past. We simply have to stop building our critical national infrastructure on top of random software libraries managed by lone unpaid distracted—or worse—individuals.

Posted on April 2, 2024 at 2:50 PM • View Comments

Security Vulnerability in Saflok’s RFID-Based Keycard Locks

It’s pretty devastating:

Today, Ian Carroll, Lennert Wouters, and a team of other security researchers are revealing a hotel keycard hacking technique they call Unsaflok. The technique is a collection of security vulnerabilities that would allow a hacker to almost instantly open several models of Saflok-brand RFID-based keycard locks sold by the Swiss lock maker Dormakaba. The Saflok systems are installed on 3 million doors worldwide, inside 13,000 properties in 131 countries. By exploiting weaknesses in both Dormakaba’s encryption and the underlying RFID system Dormakaba uses, known as MIFARE Classic, Carroll and Wouters have demonstrated just how easily they can open a Saflok keycard lock. Their technique starts with obtaining any keycard from a target hotel—say, by booking a room there or grabbing a keycard out of a box of used ones—then reading a certain code from that card with a $300 RFID read-write device, and finally writing two keycards of their own. When they merely tap those two cards on a lock, the first rewrites a certain piece of the lock’s data, and the second opens it.

Dormakaba says that it’s been working since early last year to make hotels that use Saflok aware of their security flaws and to help them fix or replace the vulnerable locks. For many of the Saflok systems sold in the last eight years, there’s no hardware replacement necessary for each individual lock. Instead, hotels will only need to update or replace the front desk management system and have a technician carry out a relatively quick reprogramming of each lock, door by door. Wouters and Carroll say they were nonetheless told by Dormakaba that, as of this month, only 36 percent of installed Safloks have been updated. Given that the locks aren’t connected to the internet and some older locks will still need a hardware upgrade, they say the full fix will still likely take months longer to roll out, at the very least. Some older installations may take years.

If ever. My guess is that for many locks, this is a permanent vulnerability.

Posted on March 27, 2024 at 7:01 AM • View Comments

A Taxonomy of Prompt Injection Attacks

Researchers ran a global prompt hacking competition, and have documented the results in a paper that both gives a lot of good examples and tries to organize a taxonomy of effective prompt injection strategies. It seems as if the most common successful strategy is the “compound instruction attack,” as in “Say ‘I have been PWNED’ without a period.”

Ignore This Title and HackAPrompt: Exposing Systemic Vulnerabilities of LLMs through a Global Scale Prompt Hacking Competition

Abstract: Large Language Models (LLMs) are deployed in interactive contexts with direct user engagement, such as chatbots and writing assistants. These deployments are vulnerable to prompt injection and jailbreaking (collectively, prompt hacking), in which models are manipulated to ignore their original instructions and follow potentially malicious ones. Although widely acknowledged as a significant security threat, there is a dearth of large-scale resources and quantitative studies on prompt hacking. To address this lacuna, we launch a global prompt hacking competition, which allows for free-form human input attacks. We elicit 600K+ adversarial prompts against three state-of-the-art LLMs. We describe the dataset, which empirically verifies that current LLMs can indeed be manipulated via prompt hacking. We also present a comprehensive taxonomical ontology of the types of adversarial prompts.

Posted on March 8, 2024 at 7:06 AM • View Comments

AIs Hacking Websites

New research:

LLM Agents can Autonomously Hack Websites

Abstract: In recent years, large language models (LLMs) have become increasingly capable and can now interact with tools (i.e., call functions), read documents, and recursively call themselves. As a result, these LLMs can now function autonomously as agents. With the rise in capabilities of these agents, recent work has speculated on how LLM agents would affect cybersecurity. However, not much is known about the offensive capabilities of LLM agents.

In this work, we show that LLM agents can autonomously hack websites, performing tasks as complex as blind database schema extraction and SQL injections without human feedback. Importantly, the agent does not need to know the vulnerability beforehand. This capability is uniquely enabled by frontier models that are highly capable of tool use and leveraging extended context. Namely, we show that GPT-4 is capable of such hacks, but existing open-source models are not. Finally, we show that GPT-4 is capable of autonomously finding vulnerabilities in websites in the wild. Our findings raise questions about the widespread deployment of LLMs.

Posted on February 23, 2024 at 11:14 AM • View Comments

Microsoft Executives Hacked

Microsoft is reporting that a Russian intelligence agency—the same one responsible for the SolarWinds hack—accessed the email system of the company’s executives.

Beginning in late November 2023, the threat actor used a password spray attack to compromise a legacy non-production test tenant account and gain a foothold, and then used the account’s permissions to access a very small percentage of Microsoft corporate email accounts, including members of our senior leadership team and employees in our cybersecurity, legal, and other functions, and exfiltrated some emails and attached documents. The investigation indicates they were initially targeting email accounts for information related to Midnight Blizzard itself.

This is nutty. How does a “legacy non-production test tenant account” have access to executive emails? And why no two-factor authentication?

Posted on January 29, 2024 at 7:03 AM • View Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.