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The song remains the same

Sophos released its Active Adversary Report for Security Practitioners, which found that telemetry logs were missing in nearly 42% of the attack cases studied. In 82% of these cases, cybercriminals disabled or wiped out the telemetry to hide their tracks. The report covers Incident Response (IR) cases that Sophos analysed from January 2022 through the first half of 2023.

Gaps in telemetry decrease much-needed visibility into organisations’ networks and systems, especially since attacker dwell time (the time from initial access to detection) continues to decline, shortening the time defenders have to effectively respond to an incident.

“Time is critical when responding to an active threat; the time between spotting the initial access event and full threat mitigation should be as short as possible. The farther along in the attack chain an attacker makes it, the bigger the headache for responders. Missing telemetry only adds time to remediations that most organisations cannot afford. This is why complete and accurate logging is essential, but we are seeing that, all too frequently, organisations do not have the data they need,” said John Shier, Field CTO, Sophos.

In the report, Sophos classifies ransomware attacks with a dwell time of less than, or equal to, five days as ‘fast attacks’, which accounted for 38% of the cases studied. ‘Slow’ ransomware attacks are those with a dwell time greater than five days, which accounted for 62% of the cases.

When examining these fast and slow ransomware attacks at a granular level, there was not much variation in the tools, techniques, and living-off-the-land binaries (LOLBins) that attackers deployed, suggesting defenders do not need to reinvent their defensive strategies as dwell time shrinks. However, defenders do need to be aware that fast attacks and the lack of telemetry can hinder fast response times, leading to more destruction.

“Cybercriminals only innovate when they must, and only to the extent that it gets them to their target. Attackers are not going to change what is working, even if they are moving faster from access to detection. This is good news for organisations because they do not have to radically change their defensive strategy as attackers speed up their timelines. The same defences that detect fast attacks will apply to all attacks, regardless of speed. This includes complete telemetry, robust protections across everything, and ubiquitous monitoring,” said Shier. “The key is increasing friction whenever possible. If you make the attackers’ job harder, then you can add valuable time to respond, stretching out each stage of an attack.”

“For example, in the case of a ransomware attack, if you have more friction, then you can delay the time until exfiltration; exfiltration often occurs just before detection and is often the costliest part of the attack. We saw this happen in two incidents of Cuba ransomware. One company (Company A) had continuous monitoring in place with MDR, so we were able to spot the malicious activity and halt the attack within hours to prevent any data from being stolen. Another company (Company B) did not have this friction; they did not spot the attack until a few weeks after initial access and after Cuba had already successfully exfiltrated 75 gigabytes of sensitive data. They then called in our IR team, and a month later, they were still trying to get back to business as usual.”

To learn more about attacker behaviours, tools and techniques, read the Active Adversary Report for Security Practitioners on Sophos.com.

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