Study notes for CompTIA Certified Advanced Security Practitioner
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The document provides information on various topics for the CompTIA CASP exam, including: 1. A virtual trusted platform module (vTPM) which provides secure storage and cryptographic functions to virtual machines similarly to a physical TPM chip. 2. SELinux, which added mandatory access control to the Linux kernel to require authorization for processes to access files. 3. A storage area network (SAN) that provides block-level access to consolidated storage over a dedicated network, rather than using a local area network. 4. Issues with using BitLocker to encrypt the drive of a computer with multiple operating systems installed, such as only being available on certain Windows versions and requiring recovery keys
![8. Microsoft Group Policies
Group Policy, in part, controls what users can and cannot do on a computer system: for
example, to enforce a password complexity policy that prevents users from choosing an
overly simple password, to allow or prevent unidentified users from remote computers to
connect to a network share, to block access to the Windows Task Manager or to restrict
access to certain folders. A set of such configurations is called a Group Policy Object
(GPO).
As part of Microsoft's IntelliMirror technologies, Group Policy aims to reduce the cost of
supporting users. IntelliMirror technologies relate to the management of disconnected
machines or roaming users and include roaming user profiles, folder redirection, and
offline files.14
Group Policy Objects are processed in the following order (from top to bottom)
1. Local - Any settings in the computer's local policy. Prior to Windows Vista, there
was only one local group policy stored per computer. Windows Vista and later
Windows versions allow individual group policies per user accounts.[5]
2. Site - Any Group Policies associated with the Active Directory site in which the
computer resides. (An Active Directory site is a logical grouping of computers,
intended to facilitate management of those computers based on their physical
proximity.) If multiple policies are linked to a site, they are processed in the order
set by the administrator.
3. Domain - Any Group Policies associated with the Windows domain in which the
computer resides. If multiple policies are linked to a domain, they are processed
in the order set by the administrator.
4. Organizational Unit - Group policies assigned to the Active Directory
organizational unit (OU) in which the computer or user are placed. (OUs are
logical units that help organizing and managing a group of users, computers or
other Active Directory objects.) If multiple policies are linked to an OU, they are
processed in the order set by the administrator.
14 https://en.wikipedia.org/wiki/Group_Policy](https://image.slidesharecdn.com/notesforthecomptiacaspexam-170311002811/85/Study-notes-for-CompTIA-Certified-Advanced-Security-Practitioner-8-320.jpg)
Study notes for CompTIA Certified Advanced Security Practitioner
- 1. Notes for the CompTIA CASP exam Posted as a courtesy by: Dave Sweigert, CEH, CISSP, CISA, HCISPP, PCIP, PMP, SEC+ 1. vTPM Virtual Trusted Platform Module (vTPM). A vTPM is a software module that performs the function of a Trusted Platform Module (TPM). The TPM is a specialized chip on an endpoint device that stores RSA encryption keys specific to the host system for hardware authentication. Each TPM chip contains an RSA key pair called the Endorsement Key (EK). The vTPM makes secure storage and cryptographic functions available to operating systems and applications running in virtual machines. NOTE: BitLocker disk encryption normally requires a TPM on Windows. Microsoft’s EFS encryption can never use a TPM. The new “device encryption” feature on Windows 10 and 8.1 also requires a modern TPM, which is why it’s only enabled on new hardware. 2. SELinux Mandatory Access Control (MAC) MAC evolved out of the multi-level security (MLS) program at NSA and DoD. An NSA research project called SELinux added a Mandatory Access Control architecture to the Linux Kernel, which was merged into the mainline version of Linux in August 20031. NOTE: Red Hat Enterprise Linux version 4 (and later versions) come with an SELinux- enabled kernel. 3. Storage Area Network (SAN) A storage area network (SAN) is a network which provides access to consolidated, block level data storage. SANs are primarily used to enhance storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear to the operating system as locally attached devices. A SAN typically has its own network of storage devices that are generally not accessible through the local area network (LAN) by other devices2. 1 https://en.wikipedia.org/wiki/Mandatory_access_control 2 https://en.wikipedia.org/wiki/Storage_area_network
- 2. 4. Multiple O/S encryption on a single SDD A solid-state drive (SSD) is a nonvolatile storage device that stores persistent data on solid-state flash memory. Solid-state drives actually aren't hard drives in the traditional sense of the term, as there are no moving parts involved. A traditional hard disk drive (HDD) consists of a spinning disk with a read/write head on a mechanical arm called an actuator. An SSD, on the other hand, has an array of semiconductor memory organized as a disk drive, using integrated circuits (ICs) rather than magnetic or optical storage media. An SSD may also be referred to as a solid-state disk3. Windows 7: The first issue here is that the only versions of Windows 7 that support Bitlocker are Enterprise and Ultimate. If you have Windows 7 Pro, you're out of luck. You may also find issues on trying to boot the Windows 7 installer on a PC with UEFI, in which case you may have to drop back to legacy mode to work round this. Unlike Windows 8, if the PC doesn't have a Trusted Platform Module, the only way to unlock the Bitlocker drive on boot is to use a USB key. Without a TPM, you cannot use a password for Bitlocker in Windows 74. If the PC is using Windows 7 Ultimate or Enterprise, or Windows 8 Pro or Enterprise, you can use BitLocker, which comes with these versions of Windows. But you have to know what you're doing. BitLocker works best in an environment where a professional IT department serves users who may not know what the word encrypt means. You can set it up so that the user doesn't even know that the drive is encrypted. When they log into Windows with their password, they get access to the encrypted files. If they log into another account, or boot with another OS, the files are unreadable. What's more, if you need to reinstall Windows, or restore the files from a backup, you'll need a special digital key that's created when you encrypt the drive. That key has to be stored elsewhere and someone has to know where to find it5. 3 http://searchsolidstatestorage.techtarget.com/definition/SSD-solid-state-drive 4 http://www.stevenmaude.co.uk/posts/a-beginners-guide-to-os-encryption-dual 5 http://www.pcworld.com/article/2858642/you-can-encrypt-your-hard-drive-but-the-protection-may-not-be- worth-the-hassle.html
- 3. 5. TOCTOU attacks In software development, time of check to time of use (TOCTTOU or TOCTOU, pronounced "TOCK too") is a class of software bug caused by changes in a system between the checking of a condition (such as a security credential) and the use of the results of that check. This is one example of a race condition.6 Time of check (TOC) — When the resource is inspected. For example, all data from the browser is considered “tainted” because a malicious user may have manipulated it. If the data passes a validation function, then the taint may be removed and the data permitted entry deeper into the app. For example, the app checks whether an email address is well-formed or text contains <script> tags. Time of use (TOU) — When the app performs an operation on the resource. For example, inserting the data into a SQL statement or inserting text into a web page. Weaknesses occur when the app assumes the state of the resource has not changed since the last check; vulnerabilities occur when the state change relates to a security control7. CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition Description Summary The software checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the software to perform invalid actions when the resource is in an unexpected state. Extended Description This weakness can be security-relevant when an attacker can influence the state of the resource between check and use. This can happen with shared resources such as files, memory, or even variables in multithreaded programs8. 6 https://en.wikipedia.org/wiki/Time_of_check_to_time_of_use 7 https://deadliestwebattacks.com/tag/toctou/ 8 https://cwe.mitre.org/data/definitions/367.html
- 4. CAPEC-29: Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. The typical example is the file access. The attacker can leverage a file access race condition by "running the race", meaning that he would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the attacker could do something such as replace the file and cause an escalation of privilege9. 6. Storage Area Network (SAN) protocols Internet Small Computer System Interface (iSCSI). iSCSI (I.P.-based protocol) works on top of the Transport Control Protocol (TCP) and allows the SCSI command to be sent end-to-end over local-area networks (LANs), wide-area networks (WANs) or the Internet. IBM developed iSCSI as a proof of concept in 1998, and presented the first draft of the iSCSI standard to the Internet Engineering Task Force (IETF) in 2000. The protocol was ratified in 2003. The major server vendors offer iSCSI as a connectivity option, to provide virtual machines with block-level access to storage volumes, without the need to deploy high- performance Fibre Channel hardware. iSCSI has been proven capable of supporting enterprise-class applications assuming that the specific solution can reach the desired level of performance and scalability and that management is simple enough not to negatively affect the total cost of ownership (TCO)10. Fibre Channel over Ethernet (FCoE). FCoe is a standards-based protocol that natively maps Fibre Channel to Ethernet for transport in a lossless Ethernet LAN. FCoE allows the consolidation of LAN and Fibre Channel SAN traffic over a single switching infrastructure in the data center. 9 https://capec.mitre.org/data/definitions/29.html 10 http://www.cisco.com/c/en/us/products/collateral/switches/nexus-5000-series-switches/white_paper_c11- 495142.html
- 6. 7. NAS vs. SANS Network-attached storage (NAS) is a file-level computer data storage server connected to a computer network providing data access to a heterogeneous group of clients. NAS is specialized for serving files either by its hardware, software, or configuration. It is often manufactured as a computer appliance – a purpose-built specialized computer. NAS systems are networked appliances which contain one or more storage drives, often arranged into logical, redundant storage containers or RAID. Network-attached storage removes the responsibility of file serving from other servers on the network. They typically provide access to files using network file sharing protocols such as NFS, SMB/CIFS, or AFP. From the mid-1990s, NAS devices began gaining popularity as a convenient method of sharing files among multiple computers. Potential benefits of dedicated network-attached storage, compared to general-purpose servers also serving files, include faster data access, easier administration, and simple configuration.11 NAS allows files to be retrieved across a computer network. It includes a dedicated hardware device (often called the head) that connects to a local area network (usually via Ethernet). This NAS “server” authenticates clients and manages file operations in much the same manner as traditional file servers, through well-established network protocols like NFS (Network File Service) and CIFS/SMB (Common Internet File System/System Message Block).12 11 https://en.wikipedia.org/wiki/Network-attached_storage 12 http://www.hosting.com/cloud-storage-the-difference-between-nas-vs-san/
- 7. http://cdn2.hubspot.net/hub/62530/file-14948438-png/images/difference-betw een-nas-and-san.png As Internet technologies like TCP/IP and Ethernet have proliferated worldwide, some SAN products are making the transition from Fibre Channel to the same IP-based approach NAS uses. Also, with the rapid improvements in disk storage technology, today's NAS devices now offer capacities and performance that once were only possible with SAN. These two industry factors have led to a partial convergence of NAS and SAN approaches to network storage.13 13 https://www.lifewire.com/san-vs-nas-818005
- 8. 8. Microsoft Group Policies Group Policy, in part, controls what users can and cannot do on a computer system: for example, to enforce a password complexity policy that prevents users from choosing an overly simple password, to allow or prevent unidentified users from remote computers to connect to a network share, to block access to the Windows Task Manager or to restrict access to certain folders. A set of such configurations is called a Group Policy Object (GPO). As part of Microsoft's IntelliMirror technologies, Group Policy aims to reduce the cost of supporting users. IntelliMirror technologies relate to the management of disconnected machines or roaming users and include roaming user profiles, folder redirection, and offline files.14 Group Policy Objects are processed in the following order (from top to bottom) 1. Local - Any settings in the computer's local policy. Prior to Windows Vista, there was only one local group policy stored per computer. Windows Vista and later Windows versions allow individual group policies per user accounts.[5] 2. Site - Any Group Policies associated with the Active Directory site in which the computer resides. (An Active Directory site is a logical grouping of computers, intended to facilitate management of those computers based on their physical proximity.) If multiple policies are linked to a site, they are processed in the order set by the administrator. 3. Domain - Any Group Policies associated with the Windows domain in which the computer resides. If multiple policies are linked to a domain, they are processed in the order set by the administrator. 4. Organizational Unit - Group policies assigned to the Active Directory organizational unit (OU) in which the computer or user are placed. (OUs are logical units that help organizing and managing a group of users, computers or other Active Directory objects.) If multiple policies are linked to an OU, they are processed in the order set by the administrator. 14 https://en.wikipedia.org/wiki/Group_Policy
- 9. http://i1-new s.softpedia-static.com/images/new s2/Microsoft-Patches-Critical-Remote-Code-Execution-Glitch-in-Group-Policy- 472770-2.jpg WMI filters You can use WMI filters to add a decision on when to apply a given group policy. This can be very useful when users or computers are located in a relatively flat structure instead of specific OU’s, for example. Filters can also help when you need to apply certain policies based on server roles, operating system version, network configuration, or other criteria. Windows evaluates these filters in the following order of overall Group Policy Processing: 1. Policies in hierarchy are located. 2. WMI Filters are checked. 3. Security settings are checked. 4. Finally, once everything has ‘passed’, a policy is applied. So we find all the policies that exist in the user/computer’s Local, Site, Domain, and OU hierarchy. Then we determine if the WMI filter evaluates as TRUE. Then we verify that the user/computer has Read and Apply Group permissions for the GPO. This means that WMI filters are still less efficient than hierarchical linking, but can definitely use filters to make decisions in a non-hierarchical Active Directory design15. 15 https://blogs.technet.microsoft.com/askds/2008/09/11/fun-with-wmi-filters-in-group-policy/
- 10. 9. Secure Boot Secure Boot is a security standard developed by members of the PC industry to help make sure that your PC boots using only software that is trusted by the PC manufacturer. When the PC starts, the firmware checks the signature of each piece of boot software, including firmware drivers (Option ROMs) and the operating system. If the signatures are good, the PC boots, and the firmware gives control to the operating system. The following versions of Windows support Secure Boot: Windows 8.1, Windows Server 2012 R2, Windows RT 8.1, Windows 8, Windows Server 2012, and Windows RT16. BIOS Basic Input/Output System (BIOS) and also known as the System BIOS, ROM BIOS or PC BIOS) is a type of firmware used to perform hardware initialization during the booting process (power-on startup) on IBM PC compatible computers, and to provide runtime services for operating systems and programs.[ BIOS works by reading the first sector of the hard drive which has the next device’s address to initialize or code to execute. BIOS also selects the boot device that needs to be initialized for starting the operating system. Since BIOS has been in use since the very beginning, it still works in 16-bit mode, limiting the amount of code that can be read and executed from the firmware ROM17. UEFI Unified Extensible Firmware Interface (UEFI) is a specification for a software program that connects a computer's firmware to its operating system (OS). UEFI is expected to eventually replace BIOS. Like BIOS, UEFI is installed at the time of manufacturing and is the first program that runs when a computer is turned on. It checks to see what hardware components the computing device has, wakes the components up and hands them over to the operating system. The new specification addresses several limitations of BIOS, including restrictions on hard disk partition size and the amount of time BIOS takes to perform its tasks. 16 https://technet.microsoft.com/en-us/library/hh824987.aspx 17 https://www.maketecheasier.com/differences-between-uefi-and-bios/
- 11. Because UEFI is programmable, original equipment manufacturer (OEM) developers can add applications and drivers, allowing UEFI to function as a lightweight operating system18. 18 http://whatis.techtarget.com/definition/Unified-Extensible-Firmware-Interface-UEFI