The threat campaign titled "Virtual Infrastructure Abuse leads to SaaS Hijacks" involves a coordinated series of compromises targeting SaaS accounts across multiple customer environments. Attackers exploit virtual private servers (VPS) infrastructure, notably from providers such as Hyonix, to conduct suspicious logins that bypass traditional security controls like geolocation-based defenses and IP reputation checks. By leveraging VPSs, attackers blend malicious traffic with legitimate activity, making detection more difficult. The core tactics observed include session hijacking, where attackers take over active user sessions to gain unauthorized access; manipulation of inbox rules to automatically redirect, delete, or hide phishing-related emails, thereby evading user and security team detection; and attempts to modify account recovery settings to maintain persistent access and hinder victim recovery efforts. These tactics align with MITRE ATT&CK techniques such as T1566.001 (Phishing: Spearphishing Attachment), T1071 (Application Layer Protocol), T1562 (Impair Defenses), T1036 (Masquerading), T1087 (Account Discovery), T1098 (Account Manipulation), T1078 (Valid Accounts), and others, indicating a sophisticated multi-stage attack chain. The attackers’ use of VPS infrastructure allows scalable, stealthy operations that can target multiple SaaS platforms simultaneously. Indicators of compromise include a set of IP addresses linked to VPS providers, which have been used in suspicious login attempts. Although no specific CVE or patch is associated, the campaign highlights an evolving threat landscape where attackers exploit cloud and virtual infrastructure to bypass conventional security controls and achieve SaaS account hijacking.

For European organizations, this threat poses significant risks due to the widespread adoption of SaaS platforms for critical business operations, including email, collaboration, and customer relationship management. Successful account hijacking can lead to unauthorized data access, leakage of sensitive information, disruption of business communications, and facilitation of further phishing attacks within or outside the organization. The manipulation of inbox rules and deletion of phishing emails can delay detection and response, increasing the window of exposure. Additionally, modification of account recovery settings can lock out legitimate users, complicating incident response and recovery efforts. Given the reliance on SaaS in sectors such as finance, healthcare, and government across Europe, the threat could lead to regulatory compliance violations (e.g., GDPR breaches), reputational damage, and financial losses. The use of VPS infrastructure to evade IP-based defenses challenges traditional perimeter security models common in European enterprises, necessitating enhanced detection capabilities.

European organizations should implement multi-layered defenses tailored to counter VPS-based SaaS hijacking attacks. Specific recommendations include: 1) Enforce strong multi-factor authentication (MFA) on all SaaS accounts, preferably using hardware tokens or app-based authenticators rather than SMS, to reduce the risk of session hijacking and credential theft. 2) Deploy anomaly detection systems that monitor login patterns for unusual IP addresses, especially those associated with known VPS providers like Hyonix, and flag or block suspicious sessions. 3) Regularly audit and monitor mailbox rules and account recovery settings for unauthorized changes, employing automated alerts to detect suspicious modifications promptly. 4) Integrate threat intelligence feeds containing indicators of compromise (e.g., the listed IP addresses) into security information and event management (SIEM) systems to enhance detection of VPS-originated malicious activity. 5) Conduct user awareness training focused on recognizing phishing attempts and the risks of session hijacking. 6) Implement conditional access policies that restrict SaaS access based on device compliance, geolocation, and risk scores to limit exposure from VPS-originated logins. 7) Establish rapid incident response procedures to investigate and remediate compromised accounts, including forced password resets and revocation of active sessions. 8) Collaborate with SaaS providers to leverage their native security features and incident response support. These targeted measures go beyond generic advice by focusing on the unique aspects of VPS abuse and inbox rule manipulation in SaaS environments.