Hiding in Plain Sight: Abuse Of Trusted Applications Grows By 51%

Sophos, a global leader in innovating and delivering cybersecurity as a service, today released “The Bite from Inside: The Sophos Active Adversary Report,” an in-depth look at the changing behaviors and attack techniques that adversaries used in the first half of 2024.

The data, derived from nearly 200 incident response [IR] cases from across both the Sophos X-Ops IR team and Sophos X-Ops Managed Detection and Response [MDR] team, found that attackers are leveraging trusted applications and tools on Windows systems, commonly called “living off the land” binaries, to conduct discovery on systems and maintain persistence. When compared to 2023, Sophos saw a 51% increase in abusing “Living off the Land” binaries or LOLbins; since 2021, it’s increased by 83%.

Among the 187 unique Microsoft LOLbins detected in the first half of the year, the most frequently abused trusted application was remote desktop protocol [RDP]. Of the nearly 200 IR cases analyzed, attackers abused RDP in 89% of them. This dominance continues a trend first observed in the 2023 Active Adversary report in which RDP abuse was prevalent in 90% of all IR cases investigated.

“Living-off-the-land not only offers stealth to an attacker’s activities but also provides a tacit endorsement of their activities. While abusing some legitimate tools might raise a few defenders’ eyebrows, and hopefully some alerts, abusing a Microsoft binary often has the opposite effect. Many of these abused Microsoft tools are integral to Windows and have legitimate uses, but it’s up to system administrators to understand how they are used in their environments and what constitutes abuse. Without nuanced and contextual awareness of the environment, including continuous vigilance to new and developing events within the network, today’s stretched IT teams risk missing key threat activity that often leads to ransomware,” says John Shier, field CTO, Sophos.

In addition, the report found that, despite the government disruption of LockBit’s main leak website and infrastructure in February, LockBit was the most frequently encountered ransomware group, accounting for approximately 21% of infections in the first half of 2024.

Other key findings from the latest Active Adversary Report:

Root Cause of Attacks: Continuing a trend first noted in the Active Adversary Report for Tech Leaders, compromised credentials are still the number one root cause of attacks, accounting for the root cause in 39% of cases. This is, however, a decline from the 56% noted in 2023

Network Breaches Dominate for MDR: When examining solely the cases from the Sophos MDR team, network breaches were the dominant incident the team encountered

Dwell Times Are Shorter for MDR Teams: For cases from the Sophos IR team, dwell time [the time from when an attack starts to when it’s detected] has remained approximately eight days. However, with MDR, the median dwell time is just one day for all types of incidents and only three days for ransomware attacks

The Most Frequently Compromised Active Directory Servers Are Nearing End of Life: Attackers most frequently compromised the 2019, 2016, and 2012 server versions of Active Directory [AD]. All three of these versions are now out of mainstream Microsoft support—one step before they become end-of-life [EOL] and impossible to patch without paid support from Microsoft. In addition, a full 21% of the AD server versions compromised were already EOL.

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