54-685: AVT may refer to: Advanced volatile threat , cyberattack not requiring file on hard drive Alijah Vera-Tucker , American football player Arginine vasotocin , a hormone Asociación de Víctimas del Terrorismo (Association of Victims of Terrorism), Spain Audiovisual translation , a specialized branch of translation Avnet , American electronics company (NASDAQ stock symbol AVT) AVT Statistical filtering algorithm Two US Navy hull classification symbols: Aircraft transport (AVT) and Auxiliary aircraft landing training ship (AVT) Topics referred to by
108-470: A System.alt hive because NTLDR on those versions of Windows can process the System.log file to bring up to date a System hive that has become inconsistent during a shutdown or crash. In addition, the %SystemRoot%\Repair folder contains a copy of the system's registry hives that were created after installation and the first successful startup of Windows. Each registry data file has an associated file with
162-545: A roaming profile , then this file will be copied to and from a server at logout and login respectively. A second user-specific registry file named UsrClass.dat contains COM registry entries and does not roam by default. Windows NT systems store the registry in a binary file format which can be exported, loaded and unloaded by the Registry Editor in these operating systems. The following system registry files are stored in %SystemRoot%\System32\config\ : The following file
216-541: A ".log" extension that acts as a transaction log that is used to ensure that any interrupted updates can be completed upon next startup. Internally, Registry files are split into 4 kB "bins" that contain collections of "cells". The registry files are stored in the %WINDIR% directory under the names USER.DAT and SYSTEM.DAT with the addition of CLASSES.DAT in Windows ME. Also, each user profile (if profiles are enabled) has its own USER.DAT file which
270-487: A "key". The terms are a holdout from the 16-bit registry in Windows 3, in which registry keys could not contain arbitrary name/data pairs, but rather contained only one unnamed value (which had to be a string). In this sense, the Windows 3 registry was like a single associative array, in which the keys (in the sense of both 'registry key' and 'associative array key') formed a hierarchy, and the registry values were all strings. When
324-407: A backup of the registry be performed before the change. When a program is removed from control panel, it may not be completely removed and, in case of errors or glitches caused by references to missing programs, the user might have to manually check inside directories such as program files. After this, the user might need to manually remove any reference to the uninstalled program in the registry. This
378-400: A computer at a crime scene. Traditional methods direct the investigator to: Fileless malware subverts the forensics models, as evidence acquisition can only take place against a memory image that has been obtained from a live running system that is to be investigated. This method, however, can itself compromise the acquired host's memory image and render legal admissibility questionable, or at
432-502: A multi-user scenario. By contrast, the Windows Registry stores all application settings in one logical repository (but a number of discrete files) and in a standardized form. According to Microsoft , this offers several advantages over .INI files. Since file parsing is done much more efficiently with a binary format, it may be read from or written to more quickly than a text INI file. Furthermore, strongly typed data can be stored in
486-486: A numeric constant) defining how to parse this data. The standard types are: The keys at the root level of the hierarchical database are generally named by their Windows API definitions, which all begin "HKEY". They are frequently abbreviated to a three- or four-letter short name starting with "HK" (e.g. HKCU and HKLM). Technically, they are predefined handles (with known constant values) to specific keys that are either maintained in memory, or stored in hive files stored in
540-484: A quick and silent manner, when standard forensic investigatory practices are ill-prepared for the threat. Windows Registry The Windows Registry is a hierarchical database that stores low-level settings for the Microsoft Windows operating system and for applications that opt to use the registry. The kernel , device drivers , services , Security Accounts Manager , and user interfaces can all use
594-524: A report titled: "Fileless attacks against enterprise networks" which implicates variants of this type of malware, and its latest incarnations, affecting 140 enterprise networks across the globe with banks, telecommunication companies and government organizations being the top targets. The report details how a variant of fileless malware is using PowerShell scripts (located within the Microsoft Windows Registry system) to launch an attack against
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#1732852335487648-412: A syntax similar to Windows' path names, using backslashes to indicate levels of hierarchy. Keys must have a case insensitive name without backslashes. The hierarchy of registry keys can only be accessed from a known root key handle (which is anonymous but whose effective value is a constant numeric handle) that is mapped to the content of a registry key preloaded by the kernel from a stored "hive", or to
702-668: A system interrupt before gaining access to their control flow; examples of which were seen in viruses such as Frodo, The Dark Avenger , Number of the Beast. These techniques evolved by way of temporary memory resident viruses and were seen in famous examples such as: Anthrax, Monxla and took on their truer fileless nature by way of in-memory injected network viruses/worms such as CodeRed and Slammer . More modern evolutionary incarnations have been seen in viruses such as Stuxnet , Duqu , Poweliks, and Phasebot. On February 8, 2017, Kaspersky Lab's Global Research & Analysis Team published
756-467: A target's machine leveraging a common attack framework called Metasploit with supporting attack tools such as Mimikatz , and leveraging standard Windows utilities such as ‘SC’ and ‘NETSH’ to assist with lateral movement. The malware was only detected after a bank identified the Metasploit Meterpreter code running in physical memory on a central domain controller (DC). Kaspersky Labs is not
810-535: A value (and its data), the values to be removed must have a minus sign ("-") after the equal sign ("="). For example, to remove only the "Value A" and "Value B" values (and their data) from the HKLM\SOFTWARE\Foobar key: To remove only the Default value of the key HKLM\SOFTWARE\Foobar (and its data): Lines beginning with a semicolon are considered comments: Windows group policies can change registry keys for
864-440: Is admissible in a court of law. Many well-known digital forensic process models such as: Casey 2004, DFRWS 2001, NIJ 2004, Cohen 2009, all embed either an examination and/or analysis phase into their respective models, implying that evidence can be obtained/collected/preserved by some mechanism. The difficulty becomes apparent when considering the standard operating procedures of digital investigators and how they should deal with
918-483: Is also simplified as the registry can be accessed over a network connection for remote management/support, including from scripts, using the standard set of APIs , as long as the Remote Registry service is running and firewall rules permit this. Because the registry is a database, it offers improved system integrity with features such as atomic updates . If two processes attempt to update the same registry value at
972-509: Is created each time the system boots and performs hardware detection. Individual settings for users on a system are stored in a hive (disk file) per user. During user login, the system loads the user hive under the HKEY_USERS key and sets the HKCU (HKEY_CURRENT_USER) symbolic reference to point to the current user. This allows applications to store/retrieve settings for the current user implicitly under
1026-405: Is designed to work in memory, so its existence on the system lasts only until the system is rebooted . Fileless malware is sometimes considered synonymous with in-memory malware as both perform their core functionalities without writing data to disk during the lifetime of their operation. This has led some commentators to claim that this variant strain is nothing new and simply a “redefinition of
1080-732: Is different from Wikidata All article disambiguation pages All disambiguation pages Advanced volatile threat Fileless malware is a variant of computer related malicious software that exists exclusively as a computer memory -based artifact i.e. in RAM . It does not write any part of its activity to the computer's hard drive , thus increasing its ability to evade antivirus software that incorporate file-based whitelisting, signature detection, hardware verification, pattern-analysis, time-stamping, etc., and leaving very little evidence that could be used by digital forensic investigators to identify illegitimate activity. Malware of this type
1134-448: Is located in the user's profile directory in %WINDIR%\Profiles\<Username>\ . The only registry file is called REG.DAT and it is stored in the %WINDIR% directory. To access the registry files, the device needs to be set in a special mode using either: If any of the above methods worked, the device's registry files can be found in the following location: The registry contains important configuration information for
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#17328523354871188-441: Is not a requirement for Windows applications to use the Windows Registry. For example, .NET Framework applications use XML files for configuration, while portable applications usually keep their configuration files with their executables . Prior to the Windows Registry, . INI files stored each program's settings as a text file or binary file , often located in a shared location that did not provide user-specific settings in
1242-493: Is not required to use an application. Abbreviated HKLM, HKEY_LOCAL_MACHINE stores settings that are specific to the local computer. The key located by HKLM is actually not stored on disk, but maintained in memory by the system kernel in order to map all the other subkeys. Applications cannot create any additional subkeys. On Windows NT, this key contains four subkeys, "SAM", "SECURITY", "SYSTEM", and "SOFTWARE", that are loaded at boot time within their respective files located in
1296-503: Is stored in .REG files using the following syntax: The Default Value of a key can be edited by using "@" instead of "Value Name": String values do not require a <Value type> (see example), but backslashes ('\') need to be written as a double-backslash ('\\'), and quotes ('"') as backslash-quote ('\"'). For example, to add the values "Value A", "Value B", "Value C", "Value D", "Value E", "Value F", "Value G", "Value H", "Value I", "Value J", "Value K", "Value L", and "Value M" to
1350-417: Is stored in each user's profile folder: For Windows 2000, Server 2003 and Windows XP, the following additional user-specific file is used for file associations and COM information: For Windows Vista and later, the path was changed to: Windows 2000 keeps an alternate copy of the registry hives (.ALT) and attempts to switch to it when corruption is detected. Windows XP and Windows Server 2003 do not maintain
1404-412: Is usually done by using RegEdit.exe. Editing the registry is sometimes necessary when working around Windows-specific issues e.g. problems when logging onto a domain can be resolved by editing the registry. Windows Registry can be edited manually using programs such as RegEdit.exe, although these tools do not expose some of the registry's metadata such as the last modified date. The registry editor for
1458-524: The system registry , in-memory processes and service areas . Fileless malware commonly employs the Living off the Land (LotL) technique which refers to the use of pre-existing operating system binaries to perform tasks. The goal of this technique is to avoid unnecessarily dropping extra malware on the system to perform tasks that can be done using already existing resources, this aids in stealth, primarily because
1512-445: The %SystemRoot%\System32\config\ folder. A fifth subkey, "HARDWARE", is volatile and is created dynamically, and as such is not stored in a file (it exposes a view of all the currently detected Plug-and-Play devices). On Windows Vista and above, a sixth and seventh subkey, "COMPONENTS" and "BCD", are mapped in memory by the kernel on-demand and loaded from %SystemRoot%\System32\config\COMPONENTS or from boot configuration data, \boot\BCD on
1566-486: The 3.1/95 series of operating systems is RegEdit.exe and for Windows NT it is RegEdt32.exe; the functionalities are merged in Windows XP. Optional and third-party tools similar to RegEdit.exe are available for many Windows CE versions. Registry Editor allows users to perform the following functions: .REG files (also known as Registration entries) are text-based human-readable files for exporting and importing portions of
1620-418: The 32-bit registry was created, so was the additional capability of creating multiple named values per key, and the meanings of the names were somewhat distorted. For compatibility with the previous behavior, each registry key may have a "default" value, whose name is the empty string. Each value can store arbitrary data with variable length and encoding, but which is associated with a symbolic type (defined as
1674-403: The HKCU key. Not all hives are loaded at any one time. At boot time, only a minimal set of hives are loaded, and after that, hives are loaded as the operating system initializes and as users log in or whenever a hive is explicitly loaded by an application. The registry is physically stored in several files, which are generally obfuscated from the user-mode APIs used to manipulate the data inside
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1728-435: The HKLM\SOFTWARE\Foobar key: Data from .REG files can be added/merged with the registry by double-clicking these files or using the /s switch in the command line. REG files can also be used to remove registry data. To remove a key (and all subkeys, values and data), the key name must be preceded by a minus sign ("-"). For example, to remove the HKLM\SOFTWARE\Foobar key (and all subkeys, values and data), To remove
1782-590: The Win32 API, or by synonymous abbreviations (depending on applications): Like other files and services in Windows, all registry keys may be restricted by access control lists (ACLs), depending on user privileges, or on security tokens acquired by applications, or on system security policies enforced by the system (these restrictions may be predefined by the system itself, and configured by local system administrators or by domain administrators). Different users, programs, services or remote systems may only see some parts of
1836-518: The atomicity guarantees across multiple key or value changes with traditional commit–abort semantics. (Note however that NTFS provides such support for the file system as well, so the same guarantees could, in theory, be obtained with traditional configuration files.) The registry contains two basic elements: keys and values . Registry keys are container objects similar to folders. Registry values are non-container objects similar to files. Keys may contain values and subkeys. Keys are referenced with
1890-486: The content of a subkey within another root key, or mapped to a registered service or DLL that provides access to its contained subkeys and values. E.g. HKEY_LOCAL_MACHINE\Software\Microsoft\Windows refers to the subkey "Windows" of the subkey "Microsoft" of the subkey "Software" of the HKEY_LOCAL_MACHINE root key. There are seven predefined root keys, traditionally named according to their constant handles defined in
1944-405: The crucial differentiation is the method of inception and prolongation. Most malware's infection vector involves some writing to the hard disk, in order for it to be executed, whose origin could take the form of an infected file attachment, external media device e.g. USB, peripheral, mobile phone etc., browser drive-by, side-channel etc. Each of the aforementioned methods has to have contact with
1998-427: The hierarchy or distinct hierarchies from the same root keys. Registry values are name/data pairs stored within keys. Registry values are referenced separately from registry keys. Each registry value stored in a registry key has a unique name whose letter case is not significant. The Windows API functions that query and manipulate registry values take value names separately from the key path or handle that identifies
2052-428: The host system's hard drive, in some form or another, meaning that even when employing the stealthiest anti-forensic methods, some form of the infected residue will be left on the host media. Fileless malware on the other hand, from the point of inception until process termination (usually by way of a system reboot), aims never to have its contents written to disk. Its purpose is to reside in volatile system areas such as
2106-603: The local filesystem and loaded by the system kernel at boot time and then shared (with various access rights) between all processes running on the local system, or loaded and mapped in all processes started in a user session when the user logs on the system. The HKEY_LOCAL_MACHINE (local machine-specific configuration data) and HKEY_CURRENT_USER (user-specific configuration data) nodes have a similar structure to each other; user applications typically look up their settings by first checking for them in "HKEY_CURRENT_USER\Software\Vendor's name\Application's name\Version\Setting name", and if
2160-467: The only company to have identified such emerging trends, with most of the principal IT security anti-malware companies coming forward with similar findings: Symantec, Trend Micro , and Cybereason. The emergence of malware that operates in a fileless way presents a major problem to digital forensic investigators, whose reliance on being able to obtain digital artifacts from a crime scene is critical to ensuring chain of custody and producing evidence that
2214-423: The operating system, for installed applications as well as individual settings for each user and application. A careless change to the operating system configuration in the registry could cause irreversible damage, so it is usually only installer programs which perform changes to the registry database during installation/configuration and removal. If a user wants to edit the registry manually, Microsoft recommends that
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2268-464: The parent key. Registry values may contain backslashes in their names, but doing so makes them difficult to distinguish from their key paths when using some legacy Windows Registry API functions (whose usage is deprecated in Win32). The terminology is somewhat misleading, as each registry key is similar to an associative array , where standard terminology would refer to the name part of each registry value as
2322-477: The pre-existing system binaries are commonly signed and trusted. An example is an attacker using PsExec to connect to a target system. Fileless malware is an evolutionary strain of malicious software that has taken on a steady model of self-improvement/enhancement with a drive towards clearly defined focused attack scenarios, whose roots can be traced back to the terminate-and-stay-resident viral programs that, once they were launched, would reside in memory awaiting
2376-406: The program, are all added to the Windows Registry. When introduced with Windows 3.1 , the Windows Registry primarily stored configuration information for COM -based components. Windows 95 and Windows NT extended its use to rationalize and centralize the information in the profusion of INI files , which held the configurations for individual programs, and were stored at various locations. It
2430-545: The registry using an INI -based syntax. On Windows 2000 and later, they contain the string Windows Registry Editor Version 5.00 at the beginning, while on Windows 9x and NT 4.0 systems, they contain the string REGEDIT4 . Windows 2000 and later REG files are Unicode -based, while on Windows 9x and NT 4.0 systems, they are ANSI -based. Windows 9x format .REG files are compatible with Windows 2000 and later. The Registry Editor on Windows on these systems also supports exporting .REG files in Windows 9x/NT format. Data
2484-507: The registry, as opposed to the text information stored in .INI files. This is a benefit when editing keys manually using regedit.exe , the built-in Windows Registry Editor. Because user-based registry settings are loaded from a user-specific path rather than from a read-only system location, the registry allows multiple users to share the same machine, and also allows programs to work for less privileged users. Backup and restoration
2538-506: The registry. Depending upon the version of Windows, there will be different files and different locations for these files, but they are all on the local machine. The location for system registry files in Windows NT is %SystemRoot%\System32\config\ ; the user-specific HKEY_CURRENT_USER user registry hive is stored in Ntuser.dat inside the user profile. There is one of these per user; if a user has
2592-429: The registry. The registry also allows access to counters for profiling system performance. In other words, the registry or Windows Registry contains information, settings, options, and other values for programs and hardware installed on all versions of Microsoft Windows operating systems. For example, when a program is installed, a new subkey containing settings such as a program's location, its version, and how to start
2646-403: The same term [REDACTED] This disambiguation page lists articles associated with the title AVT . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=AVT&oldid=1187882030 " Category : Disambiguation pages Hidden categories: Short description
2700-470: The same time, one process's change will precede the other's and the overall consistency of the data will be maintained. Where changes are made to .INI files, such race conditions can result in inconsistent data that does not match either attempted update. Windows Vista and later operating systems provide transactional updates to the registry by means of the Kernel Transaction Manager , extending
2754-408: The setting is not found, look instead in the same location under the HKEY_LOCAL_MACHINE key. However, the converse may apply for administrator-enforced policy settings where HKLM may take precedence over HKCU. The Windows Logo Program has specific requirements for where different types of user data may be stored, and that the concept of least privilege be followed so that administrator-level access
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#17328523354872808-424: The system partition. Even though the registry presents itself as an integrated hierarchical database, branches of the registry are actually stored in a number of disk files called hives . (The word hive constitutes an in-joke .) Some hives are volatile and are not stored on disk at all. An example of this is the hive of the branch starting at HKLM\HARDWARE. This hive records information about system hardware and
2862-402: The very least, instill enough reasonable doubt that the weight of the evidence presented may be drastically reduced, increasing the chances that Trojan horse or "some other dude done it" defenses may be used more effectively. This renders this type of malware extremely attractive to adversaries wishing to secure a foothold in a network, perform difficult to trace lateral movement and do so in
2916-484: The well-known term, memory resident virus”, whose pedigree can be traced back to the 1980s with the birth of the Lehigh Virus that was developed by the originator of the term, Fred Cohen , and became influential with his paper on the topic. This synonymy is however incorrect. Although the aforementioned behavioral execution environment is the same, in both cases i.e. both malware variants are executed in system memory,
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