Recent developments in cybersecurity have revealed a sophisticated new malware strain specifically designed to target Microsoft’s Internet Information Services (IIS) web servers. Utilizing advanced C++ programming, this malware employs clever evasion techniques that allow it to operate under the radar, disguising its harmful activities as routine system processes.

The malware cleverly mimics the legitimate Windows command-line utility, cmd.exe, thus evading detection while executing various malevolent tasks, including credential harvesting, lateral movement across networks, and data exfiltration.

This alarming discovery was made by cybersecurity experts at Palo Alto Networks’ Unit 42 during an incident response operation at a financial institution in Europe, highlighting the need for enhanced vigilance among organizations using IIS.

Attackers are exploiting a vulnerability within an IIS module, injecting malicious code directly into server memory. This innovative approach allows the malware to evade traditional file-based detection mechanisms, making it significantly harder to uncover. Unlike conventional IIS malware, this variant operates solely in memory and utilizes encrypted HTTP/2 channels to communicate with command-and-control (C2) servers, effectively masquerading as standard administrative traffic.

The malware’s most striking attribute is its implementation of process hollowing—a technique that allows it to run within the confines of a suspended cmd.exe instance. By replacing the legitimate cmd.exe code with its own custom C++ routines, the malware inherits the trusted process name, effectively fooling behavioral analysis tools that are designed to detect suspicious activities.

A code snippet reconstructed from the malware sheds light on its intricate injection mechanism: ```cpp HANDLE hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, targetPID); LPVOID remoteMem = VirtualAllocEx(hProcess, NULL, payloadSize, MEM_COMMIT, PAGE_EXECUTE_READWRITE); WriteProcessMemory(hProcess, remoteMem, maliciousPayload, payloadSize, NULL); CreateRemoteThread(hProcess, NULL, 0, (LPTHREAD_START_ROUTINE)remoteMem, NULL, 0, NULL); ```

To ensure persistent presence within the affected systems, the malware utilizes various techniques, including modifications of registry keys and the creation of new services. Additionally, it employs Windows Management Instrumentation (WMI) for seamless lateral movement through networks.

One notable tactic involves intercepting HTTP requests through custom IIS filters, allowing it to maintain a low profile by dynamically adjusting its behavior according to traffic patterns. This advanced command execution framework makes use of Windows’ user-mode asynchronous procedure calls (APCs) to queue malicious tasks while preserving the appearance of legitimate cmd.exe activity. Consequently, attackers can execute reconnaissance commands like "whoami," "ipconfig," and "netstat" without sounding any alarms on endpoint detection systems.

In light of this emergent threat, security teams are advised to vigilantly monitor for unusual memory allocations or unexpected cmd.exe instances with open network connections on IIS servers. Palo Alto Networks has proactively released detection rules aimed at identifying anomalous WMI event subscriptions and irregular IIS module load patterns.

As of now, there is no available patch for the underlying IIS vulnerability, underscoring the critical need for enhanced configuration hardening and continuous memory monitoring as essential defense measures against this stealthy malware threat.

Stay alert and fortified; the threat landscape is evolving, and organizations must adapt to protect their digital assets!