By David Liebenberg and Caitlin Huey.
While the security community made a great effort to warn users of the exploitation of several Microsoft Exchange Server zero-day vulnerabilities, it was still the biggest threat Cisco Talos Incident Response (CTIR) saw this past quarter. These vulnerabilities, tracked as CVE-2021-26855, CVE-2021-26857, CVE-2021-26858 and CVE-2021-27065, comprised around 35 percent of all incidents investigated.
This shows that when a vulnerability is recently disclosed, severe, and widespread, CTIR will often see a corresponding rise in engagements in which the vulnerabilities in question are involved. Thankfully, the majority of these incidents involved scanning and not post-compromise behavior, such as file encryption or evidence of exfiltration.
While CTIR’s focus was largely on the Microsoft Exchange Server vulnerabilities this quarter, ransomware continued to be a persistent and growing problem. This quarter featured several ransomware families that we have not previously encountered in CTIR engagements, including MountLocker, Zeppelin and Avaddon. These families fit the ransomware-as-a-service (RaaS) model and are typically deployed with Cobalt Strike and are delivered by an initial commodity trojan loader. These ransomware families also engage in double extortion, threatening to publish victim data if the ransom demand is not met.
Looking forward, Q4 saw a relative rise in Dridex infections beginning in late March, which ha ..
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