Researchers recently uncovered two new backdoors implanted within the infrastructure of a European Ministry of Foreign Affairs (MFA) and its diplomatic missions. Slovakian cybersecurity firm ESET who found these two new backdoors dubbed “LunarWeb” and “LunarMail,” attributed them to the Turla cyberespionage group believed to be aligned with Russian interests. Turla has operated since at least 2004, possibly starting in the late 1990s. Linked to the Russian FSB, Turla primarily targets high-profile entities like governments and diplomatic organizations in Europe, Central Asia and the Middle East. Notably, they have breached significant organizations such as the US Department of Defense in 2008 and the Swiss defense company RUAG in 2014. Researchers believe the Lunar toolset that has been used since at least 2020 is an addition to the arsenal of Russia-aligned cyberespionage group Turla based on the similarities between the tools’ tactics, techniques, and procedures (TTPs) and past activities.

LunarWeb Backd: Used to Navigate the Digital Terrain

LunarWeb backdoor stealthily infiltrates servers, establishing its foothold within the targeted infrastructure. Operating covertly, it communicates via HTTP(S) while mirroring legitimate traffic patterns to obfuscate its presence. Concealment is key in LunarWeb's playbook. For this the backdoor used steganography technique. This backdoor covertly embeds commands within innocuous images, effectively evading detection mechanisms. LunarWeb's loader, aptly named LunarLoader, showcases remarkable versatility, the researchers noted. Whether masquerading as trojanized open-source software or operating in standalone form, this entry point demonstrates the adaptability of the adversary's tactics.

LunarMail: Used to Infiltrate Individual Workstations

LunarMail takes a different approach as compared to LunarWeb. It embeds itself within Outlook workstations. Leveraging the familiar environment of email communications, this backdoor carries out its spying activities remaining hidden amidst the daily deluge of digital correspondence that its victims receive on their workstations. [caption id="attachment_68881" align="aligncenter" width="1024"] LunarMail Operation (credit: ESET)[/caption] On first run, the LunarMail backdoor collects information on the environment variables, and email addresses of all outgoing email messages. It then communicates with the command and control server through the  Outlook Messaging API to receive further instructions. LunarMail is capable of writing files, setting email addresses for C&C communication, create arbitrary processes and execute them, take screenshots and more. Similar to its counterpart, LunarMail harnesses the power of steganography albeit within the confines of email attachments. By concealing commands within image files, it perpetuates its covert communication channels undetected. LunarMail's integration with Outlook extends beyond mere infiltration. It manipulates email attachments, seamlessly embedding encrypted payloads within image files or PDF documents which facilitates unsuspicious data exfiltration.

Initial Access and Discovery

The initial access vectors of the Turla hackers, though not definitively confirmed, point towards the exploitation of vulnerabilities or spearphishing campaigns. The abuse of Zabbix network monitoring software is also a potential avenue of compromise, the researchers said. The compromised entities were primarily affiliated with a European MFA, which meant the intrusion was of a strategic nature. The investigation first began with the detection of a loader decrypting and running a payload from an external file, on an unidentified server. This was a previously unknown backdoor, which the researchers named LunarWeb. A similar attack chain with LunarWeb was then found deployed at a diplomatic institution of a European MFA but with a second backdoor – named LunarMail. In another attack, researchers spotted simultaneous deployments of a chain with LunarWeb at three diplomatic institutions of this MFA in the Middle East, occurring within minutes of each other. “The attacker probably had prior access to the domain controller of the MFA and utilized it for lateral movement to machines of related institutions in the same network,” the researchers noted. The threat actors displayed varying degrees of sophistication in the compromises. The coding errors and different coding styles used to develop the backdoors suggested that “multiple individuals were likely involved in the development and operation of these tools.”

Russian State Hackers Biggest Cyber Threat

Recently, Google-owned Mandiant in a detailed report stated with “high confidence” that Russian state-sponsored cyber threat activity poses the greatest risk to elections in regions with Russian interest including the European Union, the United Kingdom and the United States. Russia’s approach to election interference is multifaceted, blending cyber intrusion activities with information operations aimed at influencing public perceptions and sowing discord. Russian state-aligned cyber threat actors target election-related infrastructure for various reasons including applying pressure on foreign governments, amplifying issues aligned with Russia’s national interests, and retaliating against perceived adversaries. Groups like APT28 and UNC4057 conduct cyber espionage and information operations to achieve these objectives, Mandiant said. Media Disclaimer: This report is based on internal and external research obtained through various means. The information provided is for reference purposes only, and users bear full responsibility for their reliance on it. The Cyber Express assumes no liability for the accuracy or consequences of using this information.

After the XZ Utils discovery, people have been examining other open-source projects. Surprising no one, the incident is not unique:

The OpenJS Foundation Cross Project Council received a suspicious series of emails with similar messages, bearing different names and overlapping GitHub-associated emails. These emails implored OpenJS to take action to update one of its popular JavaScript projects to “address any critical vulnerabilities,” yet cited no specifics. The email author(s) wanted OpenJS to designate them as a new maintainer of the project despite having little prior involvement. This approach bears strong resemblance to the manner in which “Jia Tan” positioned themselves in the XZ/liblzma backdoor.

[…]

The OpenJS team also recognized a similar suspicious pattern in two other popular JavaScript projects not hosted by its Foundation, and immediately flagged the potential security concerns to respective OpenJS leaders, and the Cybersecurity and Infrastructure Security Agency (CISA) within the United States Department of Homeland Security (DHS).

The article includes a list of suspicious patterns, and another list of security best practices.

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.

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.

The European Court of Human Rights has ruled that breaking end-to-end encryption by adding backdoors violates human rights:

Seemingly most critically, the [Russian] government told the ECHR that any intrusion on private lives resulting from decrypting messages was “necessary” to combat terrorism in a democratic society. To back up this claim, the government pointed to a 2017 terrorist attack that was “coordinated from abroad through secret chats via Telegram.” The government claimed that a second terrorist attack that year was prevented after the government discovered it was being coordinated through Telegram chats.

However, privacy advocates backed up Telegram’s claims that the messaging services couldn’t technically build a backdoor for governments without impacting all its users. They also argued that the threat of mass surveillance could be enough to infringe on human rights. The European Information Society Institute (EISI) and Privacy International told the ECHR that even if governments never used required disclosures to mass surveil citizens, it could have a chilling effect on users’ speech or prompt service providers to issue radical software updates weakening encryption for all users.

In the end, the ECHR concluded that the Telegram user’s rights had been violated, partly due to privacy advocates and international reports that corroborated Telegram’s position that complying with the FSB’s disclosure order would force changes impacting all its users.

The “confidentiality of communications is an essential element of the right to respect for private life and correspondence,” the ECHR’s ruling said. Thus, requiring messages to be decrypted by law enforcement “cannot be regarded as necessary in a democratic society.”