Authentication Coercion Evolves: RPC Attack Bypasses Enterprise Security in 2024
Executive Summary
In early 2024, a new evolution in authentication coercion attacks was uncovered, where threat actors exploited an obscure and poorly monitored remote procedure call (RPC) interface to bypass authentication barriers. Attackers leveraged this vector to coerce systems and services into issuing authentication requests, enabling credential relaying and lateral movement within enterprise networks. This approach bypassed traditional multi-factor authentication and monitoring controls, putting sensitive data and operations at risk across multiple organizations. The fallout included unauthorized access, potential data exfiltration, and major concerns about the visibility of east-west traffic in enterprise environments.
This incident underscores a rising trend where attackers innovate to exploit less visible, often-overlooked system protocols. As attackers become more sophisticated, the risks posed by legacy interfaces and insufficient internal segmentation are growing, necessitating enhanced internal monitoring and alignment to zero trust principles.
Why This Matters Now
Authentication coercion attacks leveraging obscure RPC interfaces represent a pressing security gap, as many organizations lack adequate visibility and controls on internal communications. This exposes sensitive resources to credential relaying and lateral movement, making it crucial to implement deep east-west inspection, strict segmentation, and continuous anomaly detection immediately.
Attack Path Analysis
The attacker exploited an obscure and poorly monitored RPC interface to achieve initial access to the cloud environment. With this access, the adversary escalated privileges by abusing authentication mechanisms, likely coercing systems to grant higher access. These elevated privileges allowed the attacker to move laterally across internal cloud resources, utilizing east-west pathways. They established command and control channels over encrypted or covert network traffic to maintain persistence and task remote endpoints. Subsequently, sensitive data was exfiltrated out of the environment, potentially using allowed outbound channels or hiding exfiltration within legitimate-looking flows. Finally, the attack had an impact such as data exposure, account disruption, or further malicious activity dependent on attacker goals.
Kill Chain Progression
Initial Compromise
Description
Attacker exploited a rarely monitored RPC interface to gain an initial foothold in the cloud environment.
Related CVEs
CVE-2025-33073
CVSS 8.8A vulnerability in the Windows SMB client allows attackers to perform NTLM reflection attacks, leading to privilege escalation to SYSTEM level.
Affected Products:
Microsoft Windows SMB Client – All versions prior to the patch released in 2025
Exploit Status:
exploited in the wildCVE-2021-1678
CVSS 7.5A vulnerability in the Windows Print Spooler service allows attackers to relay NTLM authentication sessions, potentially leading to remote code execution.
Affected Products:
Microsoft Windows Print Spooler – All versions prior to the patch released in January 2021
Exploit Status:
exploited in the wildCVE-2021-23192
CVSS 7.5A flaw in Samba's DCE/RPC implementation allows attackers to bypass signature requirements by sending large fragmented requests, potentially leading to unauthorized access.
Affected Products:
Samba Samba – All versions prior to the patch released in March 2022
Exploit Status:
proof of conceptReferences:
MITRE ATT&CK® Techniques
Modify Authentication Process
Access Token Manipulation: Create Process with Token
Valid Accounts
Exploitation of Remote Services
Network Sniffing
Remote Services: SMB/Windows Admin Shares
Application Layer Protocol: Web Protocols
Process Injection: Process Hollowing
Potential Compliance Exposure
Mapping incident impact across multiple compliance frameworks.
PCI DSS 4.0 – Strong Authentication for Users and Administrators
Control ID: 8.3.1
NYDFS 23 NYCRR 500 – Cybersecurity Program and Access Controls
Control ID: 500.3, 500.5
DORA – ICT Risk Management Framework and Identification of ICT-related Risks
Control ID: Art. 9, Art. 10
CISA ZTMM 2.0 – Zero Trust Identity and Access Management
Control ID: Identity Pillar - Authentication, Session, and Credential Management
NIS2 Directive – Access Control and Asset Management
Control ID: Article 21(2)(d)
Sector Implications
Industry-specific impact of the vulnerabilities, including operational, regulatory, and cloud security risks.
Financial Services
Authentication bypass attacks targeting RPC interfaces threaten secure banking transactions, requiring enhanced east-west traffic security and zero trust segmentation for compliance.
Health Care / Life Sciences
RPC-based authentication coercion attacks compromise patient data systems, necessitating encrypted traffic controls and threat detection capabilities to maintain HIPAA compliance.
Government Administration
Authentication bypass vulnerabilities in government RPC systems create national security risks, demanding multicloud visibility and anomaly detection for critical infrastructure protection.
Information Technology/IT
Evolving authentication coercion attacks exploit IT infrastructure RPC interfaces, requiring comprehensive inline IPS and cloud-native security fabric implementations for defense.
Sources
- You Thought It Was Over? Authentication Coercion Keeps Evolvinghttps://unit42.paloaltonetworks.com/authentication-coercion/Verified
- Windows Hit by Authentication Coercion That Tricks Machines into Sending Credentialshttps://cyberpress.org/authentication-coercion/Verified
- Examining Relay Attacks Through the Lens of CVE-2025-33073https://zeronetworks.com/blog/examining-relay-attacks-through-the-lens-of-cve-2025-33073Verified
- Security Advisory: MSRPC Printer Spooler Relay (CVE-2021-1678)https://www.crowdstrike.com/blog/cve-2021-1678-printer-spooler-relay-security-advisory/Verified
Frequently Asked Questions
Cloud Native Security Fabric Mitigations and ControlsCNSF
Zero Trust Segmentation, traffic visibility, real-time threat detection, egress policy enforcement, and encryption would have collectively reduced the attack surface and limited the attacker's ability to move laterally, escalate privileges, exfiltrate data, or achieve impact. Granular controls across cloud and internal networks, along with rapid anomaly response, are key to stopping such authentication coercion attacks.
Control: Zero Trust Segmentation
Mitigation: Unauthenticated network reachability to sensitive RPC endpoints would have been blocked.
Control: Threat Detection & Anomaly Response
Mitigation: Detection of abnormal authentication attempts or privilege escalation activity.
Control: East-West Traffic Security
Mitigation: Blocked unauthorized workload-to-workload communications.
Control: Cloud Firewall (ACF)
Mitigation: Outbound command and control attempts detected and blocked.
Control: Egress Security & Policy Enforcement
Mitigation: Unauthorized data exfiltration attempts stopped.
Automated, distributed enforcement minimized blast radius and limited disruptive actions.
Impact at a Glance
Affected Business Functions
- User Authentication
- Access Control
- Network Security
Estimated downtime: 3 days
Estimated loss: $500,000
Potential exposure of sensitive user credentials and unauthorized access to critical systems.
Recommended Actions
Key Takeaways & Next Steps
- • Enforce identity-based segmentation and microsegmentation to tightly constrain RPC and authentication exposure.
- • Deploy real-time threat detection with baselining and automated response to detect and stop anomalous authentication behavior.
- • Apply strict east-west workload communication controls to reduce attacker lateral movement potential.
- • Implement granular egress filtering and cloud firewall policies to detect and block unauthorized outbound and exfiltration activity.
- • Continuously monitor cloud traffic across regions and resources for signs of covert command and control or privilege escalation attempts.
