A second, custom backdoor was observed being deployed in attacks on four defense contractors if the primary backdoor was removed, security researchers with Palo Alto Networks’ Unit 42 division report.
Dubbed SockDetour, the malware has been deployed “filelessly and socketlessly” as a backup backdoor mainly focused on defense contractors in the United States. Four entities were targeted and at least one organization has been compromised.
The attacks were part of the larger “TiltedTemple” advanced persistent threat (APT) cluster of activity, which has compromised at least 13 organizations in the defense, education, energy, finance, healthcare, and technology sectors. Infrastructure associated with five US states was targeted in this campaign.
As part of the attacks, vulnerabilities in Zoho ManageEngine ADSelfService Plus and ServiceDesk Plus (CVE-2021-40539 and CVE-2021-44077, respectively) were exploited for initial access. The attacks on CVE-2021-44077 started before the vulnerability was discovered.