In October 2023, The British Library was attacked by the Rhysida ransomware gang in a devastating cyberattack.

The library, a vast repository of over 170 million items, is still deep in the recovery process, but recently released an eighteen page cyber incident review describing the attack, its impact, the aftermath, and the lessons learned. The report is full of useful information, and well worth a read, even if you’re responsible for security in a much smaller organisation.

The attack and its aftermath is a reminder that big game ransomware remains the preeminent cyberthreat to organisations of all sizes, and the tactics it describes will be familiar to anyone who has read the Big Game Ransomware section of our 2024 State of Malware report.

The ransomware itself was launched on October 28, 2023, but the library believes that the Rhysida group infiltrated its systems at least three days before that. During those three days the group conducted what the library calls “hostile reconnaissance,” and exfiltrated 600GB of data.

The report also describes how the gang “hijacked native utilities” to copy databases. Using tools that are already on a victim’s network (a technique know as Living off the Land) makes it easier for ransomware gangs to avoid detection while they prepare an attack.

However, there are some details about the attack that either add to the body of knowledge, or remind us of things that are easily overlooked, so I’ve picked out some lessons from the report that can probably be usefully applied by any IT team.

1. Complexity helped the attackers

One thing that leaps off the pages of the report is how the library’s complex infrastructure aided the attackers. The report describes the library environment as an “unusually diverse and complex technology estate, including many legacy systems.” Unless you work for a brand new startup, the chances are that you recognise some of your own company network in that description, even if it isn’t as complex as the British Library.

This technical debt prevented the library from complying with security standards, “contributed to the severity of the impact of the attack,” and offered the attackers wider access than they should have had.

Most damaging of all though is the effect that carrying too much complexity has had on the library’s ability to recover:

“Our reliance on legacy infrastructure is the primary contributor to the length of time that the Library will require to recover from the attack. These legacy systems will in many cases need to be migrated to new versions, substantially modified, or even rebuilt from the ground up, either because they are unsupported and therefore cannot be repurchased or restored, or because they simply will not operate on modern servers or with modern security controls.”

It concludes, “there is a clear lesson in ensuring the attack vector is reduced as much as possible by keeping infrastructure and applications current.”

2. Endpoint protection matters

While the issue of complexity crops up again and again in the report, there is another significant finding that’s covered in just a single line—the importance of effective endpoint protection.

As devastating as the attack on the library was, it could have been worse. The attack only succeeded in compromising the organisation’s servers, but its desktops and laptops were spared because they were running a more modern “defensive software” that successfully identified and prevented the attack.

“A different software system successfully identified and prevented the encryption attack from executing on our laptop and desktop estates, but older defensive software on the server estate was unable to resist the attack.”

The clear implication is that if the system that was running on the desktops and laptops had also been running on the servers then the attack would have been thwarted.

As important as monitoring technologies like SIEM, EDR and MDR have become, it remains as true today as it ever has that every endpoint and server, whether they’re Windows, Macs, or Linux machines, needs a next-gen antivirus engine that can detect and stop known threats and block suspicious behaviour, such as malicious encryption.

3. Ransomware is 24/7

The report also mentions another potential opportunity to stop the attack. It describes how “at 01:15 on 26 October 2023, the Library’s IT Security Manager was alerted to possible malicious activity on the Library network.” The IT manager took action, monitored the situation and the escalated the incident the following morning. A subsequent detailed analysis of activity logs, “did not identify any obviously malicious activity.”

Investigations performed after the attack “identified evidence of an external presence on the Library network at 23:29 on Wednesday 25 October 2023,” and that “an unusually high volume of data traffic (440GB) had left the Library’s estate at 1.30am on 28 October.” This suggests that there were further opportunities to detect the attackers’ “hostile reconnaissance.”

We highlight this to demonstrate an important point about how ransomware gangs operate, not to second guess the IT team at the library. It seems that everyone concerned treated the incident very seriously and took appropriate action, and they have our sympathy.

What we want to draw your attention to is that all three incidents happened in the dead of night.

Groups like Rhysida make significant efforts to cover their tracks, and are likely to work at times when their targets are least well staffed. However, even as stealthy as they are, their out-of-hours activities still create opportunities for skilled security staff to detect them. The problem for defenders is that their skilled security staff need to be working at the same time as the attackers.

For many organisations, the only practical way to achieve that is through a Managed Service Provider or a service like Managed Detection and Response (MDR).

How to avoid ransomware

• Block common forms of entry. Create a plan for patching vulnerabilities in internet-facing systems quickly; and disable or harden remote access like RDP and VPNs.
• Prevent intrusions. Stop threats early before they can even infiltrate or infect your endpoints. Use endpoint security software that can prevent exploits and malware used to deliver ransomware.
• Detect intrusions. Make it harder for intruders to operate inside your organization by segmenting networks and assigning access rights prudently. Use EDR or MDR to detect unusual activity before an attack occurs.
• Stop malicious encryption. Deploy Endpoint Detection and Response software like ThreatDown EDR that uses multiple different detection techniques to identify ransomware, and ransomware rollback to restore damaged system files.
• Create offsite, offline backups. Keep backups offsite and offline, beyond the reach of attackers. Test them regularly to make sure you can restore essential business functions swiftly.
• Don’t get attacked twice. Once you’ve isolated the outbreak and stopped the first attack, you must remove every trace of the attackers, their malware, their tools, and their methods of entry, to avoid being attacked again.