Kernel Pool, Windows and Memory Analysis

In previous posts, I made references to a “live” memory analysis tool named Volatility. The concept is both logical and relatively simple. The implementation requires an understanding of the Windows, Linux, and MAC operating systems. Good or bad, nothing happens without being in computer memory and disc storage. Analysis of memory and/or discs has a trade off.

1. Computer memory is usually smaller in size than the storage capacity of a disc.
2. Analysis of memory/disc, until recently has been a manual process. Capture the resource, analyze the resource in a sandbox, write a report, and restore with the compromise removed. But with the extremely long time to detection manual analysis, while having value, takes too long. Automation and AI are now a requirement.
3. If nothing else, because of the size difference between memory and disc, memory can often be analyzed quicker than analysis of a disc.
4. Analyzing memory is a snapshot in time. Depending upon when the snap shot is taken, the malware/virus may or may not be in memory when the snap shot is captured. On a disc, the malware/virus may be in a dormant state, but the malware/virus can be detected, whether dormant or active.
5. The environment, enterprise, cloud, cell devices, IOT devices, etc can be in the tens of thousands in number of devices. Automation is a requirement.
6. In both breadth and depth, analysis of memory/disc requires a large amount of expertise. That expertise is rare. However, attackers understand the payback in having a deep understanding of resources. If defense is to be successful, the defender must also have a deep understanding of resources and understand the behavioral patterns of the attacker.

Windows Kernel Memory

Kernel memory in Windows OS plays a crucial role in the overall system’s performance, stability, and security. The kernel is the core part of the operating system that manages critical tasks, including managing memory, processes, and hardware interactions. Here’s why kernel memory is so important:

1. System Stability and Performance: Kernel memory is used to store and manage the most essential and sensitive parts of the operating system, such as the kernel itself, device drivers, and system services. Because these components are critical for the smooth operation of the system, their stability and efficient management directly impact the overall performance and reliability of the OS.
2. Security: The kernel operates in a protected memory space that is isolated from user applications. This separation ensures that user applications cannot directly access or modify kernel memory, which helps to protect the system from malicious software and potential security breaches. Ensuring the integrity and security of kernel memory is paramount for maintaining the security of the entire system.
3. Resource Management: The kernel is responsible for managing system resources, including CPU, memory, and I/O devices. Efficient management of these resources, including how memory is allocated and freed, directly affects the system’s responsiveness and ability to multitask effectively.
4. System Services and Device Drivers: Kernel memory stores the core components that provide various system-level services and interfaces for hardware devices. This includes device drivers, which facilitate communication between the operating system and hardware components. Proper functioning and efficiency of these components are crucial for the seamless operation of hardware and execution of system services.
5. Process and Thread Management: The kernel manages processes and threads, which are essential for running applications. It keeps track of process states, manages scheduling, and handles context switching. Efficient management of these tasks in kernel memory is vital for ensuring that applications run smoothly and system resources are utilized effectively.
6. In summary, kernel memory is central to the Windows operating system’s functionality. It impacts system stability, performance, security, and the efficient management of resources, processes, and hardware interactions. Ensuring the integrity and optimal management of kernel memory is essential for the smooth operation of the system.

Importance of Kernel Memory to the Attacker

Kernel memory in Windows OS is of particular interest to attackers due to its critical role in system operations and the high level of privileges it holds. Gaining access to or exploiting kernel memory can provide an attacker with significant control over the system, making it a prime target for various types of attacks. Here’s why kernel memory is important to attackers:

1. High Privilege Level: The kernel operates at the highest privilege level within the system, often referred to as ring 0 in the context of x86 architecture. This means that code running in the kernel has unrestricted access to the hardware and all system resources. An attacker who gains control over kernel memory can essentially bypass security measures, access sensitive data, and perform unrestricted actions on the system.
2. Bypass Security Mechanisms: The kernel is responsible for enforcing security policies and mechanisms, including access controls and data protection features. If an attacker can exploit vulnerabilities within the kernel or manipulate kernel memory, they can potentially disable or bypass these security mechanisms, allowing them to perform unauthorized actions without detection.
3. Rootkits and Stealth Malware: By manipulating kernel memory, attackers can install rootkits or stealthy malware that operates at the kernel level. Such malware can hide its presence from traditional security tools and maintain persistent access to the system, making detection and removal challenging.
4. Direct Hardware Access: Kernel memory provides access to and control over hardware resources. An attacker with kernel-level access can manipulate hardware directly, enabling actions like disabling security devices, modifying system components, or exfiltrating data through physical channels.
5. System-wide Impact: Exploits targeting the kernel can have a system-wide impact due to the kernel’s central role in managing system resources and processes. This can include crashing the system (denial of service), altering system behavior, or compromising the integrity and confidentiality of data processed by the system.
6. Evasion of Security Software: Many security solutions operate at the user level or rely on hooks and callbacks provided by the kernel to monitor system activity. By operating in kernel memory, attackers can evade detection by these security solutions or even manipulate them to provide false information.

Because of these reasons, securing kernel memory against unauthorized access and exploitation is a critical aspect of system security. Operating system and hardware vendors continually work to identify and patch vulnerabilities, improve isolation mechanisms, and enhance the security of kernel memory to protect against such attacks.

Objects in Kernel Memory in Windows

In the context of Windows operating systems, kernel memory contains a variety of object types that the kernel uses to manage system resources and operations. These objects are fundamental to the system’s functioning and security. Some of the key object types found in kernel memory include:

1. Processes: Represent individual executable programs. Process objects contain information about the program’s state, its threads, and resources like open handles and memory allocation.
2. Threads: The basic units of execution within processes. Each thread has its own stack and execution context, including register states and scheduling information.
3. Files: Represent open instances of files on the disk or network. File objects manage data access, read/write operations, and maintain information about file attributes and security settings.
4. Tokens: Used for security and access control. A token object represents the security context of a process or thread, containing information about the user, group memberships, and privileges.
5. Devices: Represent physical or logical devices on the system. Device objects facilitate communication between the system and hardware components, such as disks, keyboards, and network interfaces.
6. Registry Keys: Used to access and manage Windows Registry entries. Registry key objects represent open instances of registry keys and contain information about the key’s attributes and security settings.
7. Events: Synchronization objects used to signal one or more waiting threads that an event has occurred. Event objects are used for inter-thread and inter-process communication and synchronization.
8. Semaphores: Another type of synchronization object, semaphores manage access to a finite number of resources shared by multiple threads or processes.
9. Mutants (Mutexes): Mutual exclusion objects used to provide thread or process synchronization by allowing only one thread to access a resource or critical section at a time.
10. Sections (Memory Mapped Files): Represent regions of memory that can be shared between processes. Sections are used for file mapping, which allows files or devices to be mapped into the virtual address space of a process.
11. Drivers: Represent loaded device drivers, which are programs that allow the operating system to interact with hardware devices. Driver objects manage the functionality and interactions of device drivers within the system.
12. Ports and LPCs (Local Procedure Calls): Used for communication between processes in user mode and services in kernel mode. Ports and LPC objects facilitate message-based communication across different security contexts.

These objects are managed by the Windows Executive, a component of the Windows kernel, and are manipulated through system calls and kernel APIs. The management and integrity of these objects are critical for system stability, performance, and security.

Management of Kernel Memory

In Windows OS, kernel memory is managed through a system known as the Windows kernel pool. The kernel pool is a dynamic memory area allocated by the Windows kernel for storing various types of objects required by the kernel and device drivers. The management of this pool is crucial for system stability, performance, and security. The kernel pool is divided into two main types:

1. Non-Paged Pool: This portion of the kernel memory is never paged out to disk, meaning it remains in physical memory at all times. It’s used for data that must be accessible at any time, even when an interrupt is being serviced where disk access is not possible. This includes critical system structures and data that are required to process interrupts or manage hardware devices.
2. Paged Pool: This portion can be paged to and from disk based on the system’s current memory demands. It’s used for less critical data that doesn’t need to be accessed during interrupt service routines or when the system is in a state where disk access is possible and memory resources are scarce.

Management of the kernel pool involves several key mechanisms and strategies:

• Allocation and Freeing: The Windows kernel provides APIs for drivers and system components to allocate and free memory from the pool. These APIs ensure that memory is allocated as needed and released when no longer in use, helping to optimize memory usage.
• Pooling Strategy: To minimize fragmentation and manage memory efficiently, Windows uses a pooling strategy. Small allocations are grouped together in pool blocks, reducing overhead and fragmentation within the pool.
• Quota Management: Windows imposes quotas on the amount of pool memory that can be used by user-mode processes and certain system components. This helps prevent a single process or driver from consuming all available kernel memory, which could lead to system instability or crashes.
• Tagging: Memory allocations in the kernel pool can be tagged with unique identifiers, allowing for easier tracking and debugging of kernel memory usage. This is particularly useful for identifying memory leaks or excessive allocations by drivers or system components.
• Monitoring and Diagnostics: Windows provides tools and mechanisms for monitoring kernel pool usage, such as the PoolMon tool and Windows Performance Recorder (WPR). These tools help identify issues with pool usage, such as leaks or excessive allocations, by tracking pool tags and usage statistics.
• Security Measures: To protect the integrity of kernel memory, Windows implements various security measures, such as randomization of memory addresses (ASLR), pool guard pages, and strict access controls. These measures help mitigate the risk of exploitation through buffer overflows or other memory-corruption vulnerabilities.

Effective management of the kernel pool is vital to ensure that the system remains responsive, stable, and secure. It involves a balance between providing sufficient memory for kernel operations and maintaining enough free memory to prevent system resource exhaustion.

Volatility and Analysis of Kernel Memory

Volatility is an open-source framework for volatile memory analysis, often used in digital forensics and incident response. It’s not directly involved in managing kernel memory in the sense of allocation or deallocation but rather in analyzing the state of kernel memory post-mortem or during a live analysis. This can be particularly useful for understanding the actions of malicious software, diagnosing system crashes, or investigating security breaches. Here’s how Volatility can be applied to analyze kernel memory in Windows OS:

1. Memory Dump Analysis: Volatility can analyze memory dumps from Windows systems. These dumps can be obtained from live systems using tools like WinPmem or from systems that have crashed due to a Blue Screen of Death (BSOD). Analyzing these dumps can provide insights into what was happening in kernel memory at the time of the dump.
2. Process Examination: Volatility can enumerate and analyze processes that were running in memory at the time of the dump. This includes processes in kernel memory, allowing investigators to see what processes were active, their states, and associated memory usage.
3. Driver and Kernel Module Analysis: Volatility can list and examine drivers and kernel modules loaded into memory. This is crucial for understanding which drivers were active, potentially identifying malicious or rootkit drivers that were loaded into the kernel.
4. Memory Allocation Tracking: While Volatility doesn’t manage memory allocations, it can analyze and report on memory allocations within kernel memory. This can help in identifying unusual patterns of memory usage, potential memory leaks, or areas of memory overwritten by malware.
5. Registry Analysis: Volatility can access and analyze the registry hives loaded in memory. Since the registry is crucial for Windows operation and configuration, examining it can reveal configuration changes, malware persistence mechanisms, and other indicators of compromise.
6. Network Artifacts and Connections: Volatility can extract network connection information, sockets, and other network-related artifacts from memory dumps. This is valuable for identifying remote connections, potential data exfiltration attempts, or command and control (C2) activity.
7. File and Disk Artifacts: Volatility can recover and analyze file objects, handles, and disk artifacts from memory dumps. This can be useful for uncovering hidden or deleted files accessed by malicious processes or drivers.
8. Memory Forensics for Malware Analysis: Volatility is extensively used for malware analysis, particularly for identifying and understanding in-memory malware. This includes analyzing code injection, process hollowing, and other techniques that malware might use to hide in kernel or user memory.
9. Timeline Analysis: Volatility can help in constructing timelines of system and process activity from memory dumps, providing a chronological view of events leading up to the memory dump.
10. Extracting Credentials and Sensitive Information: In some cases, Volatility can be used to extract passwords, cryptographic keys, and other sensitive information that was resident in memory at the time of the dump.

Using Volatility for kernel memory analysis requires a deep understanding of Windows internals and memory forensics. It’s a powerful tool in the hands of forensic analysts and incident responders for diagnosing system issues, understanding malware behavior, and investigating security incidents.

Summary

Understanding the internals of Windows, Linux and MAC operating systems can take a significant amount of training and real world experience. Then there is the automation across thousands of resources. More than pointing, clicking and applying a control. If the window of 250+ days before detection is going to be reduced, there is value in learning the technologies and how to best apply them. Failure to make the investment will simply increase the 250+ days to detection.