Regulating remote registry access over a computer network

[0001] This invention pertains generally to computer security, and more specifically to regulating remote registry access.

[0002] Networked computers are vulnerable to malicious computer code attacks, such as worms, viruses and Trojan horses. As used herein, “malicious computer code” is any code that enters a computer without an authorized user's knowledge and/or without an authorized user's consent.

[0003] A majority of malicious code today is targeted at computers running the Microsoft Windows® operating system, because of its market prevalence. Therefore, it is important to identify and patch security vulnerabilities in Windows®. One important security vulnerability today is the remote registry access service provided in Windows NT® family of operating systems (Windows® 2000, XP, 2003, etc.).

[0004] These versions of Windows® provide a function called RegConnectRegistry, which allows a caller on a source computer to remotely access the registry of a target computer, thus providing open remote access to the registry database on any reachable computer within a network. In order to access a remote registry, the calling process on the source computer must be owned by a user with logon privileges on the target computer. However, where this is the case, knowledge of the IP address of the target computer is all that is needed for remote registry access.

[0005] Clearly, this provides an opportunity for malicious code that has managed to infect the source computer to access highly sensitive data in registries of remote computers that the malicious code has not managed to infect. A common ability of computer worms is to be able to generate mass numbers of IP addresses within seconds. If such a worm utilizes its IP address list and attempts to access each target computer's registry remotely, the worm might be able to access many remote registries very quickly.

[0006] Once malicious code has accessed a remote registry, it can inflict damage to the target computer at will. The malicious code could, for example, read certain fields in the registry to collect sensitive information about the hardware environment, the software environment, the users of this computer, etc. The malicious code could also collect information about the installed applications, and based on that information, target a customized malicious attack of the remote computer. The malicious code could even be polymorphic, and able to generate different malicious infections based on its own evaluation of the target computer.

[0007] The malicious code could also scan different well-known areas in the registry to harvest e-mail addresses to be used for mass mailing of itself from the machine it has maliciously accessed. The worm may read the registry database to enumerate the names of the current existing shares on the target victim machine. After that it can try to access those shares directly. The worm might have enough access rights to access the target share. Otherwise, it can start to apply a brute-force attack to every remote share it was able to identify. This will confuse a local malicious code blocking engine because the worm does not have to issue certain network API calls to enumerate share names within the network.

[0008] Malicious code could also modify the “run” entry on the target computer to point to itself, or to custom malicious code that it produced specifically to attack the target computer. Malicious code with remote registry access could even modify registry entries on the target computer to disallow anti-virus programs from running when the computer restarts. The malicious code could also destroy security attributes stored in the registry to violate the integrity of the security data, and modify the system policies stored in the registry to allow or block certain actions.

[0009] Because there are so many harmful things that malicious code can do after gaining remote access to the registry database of a remote computer, what is needed are methods, systems and computer readable media for regulating remote registry access. More specifically, remote registry access should be regulatable at both the source computer and the target computer.

[0010] The present invention comprises methods, systems and computer readable media for a remote registry access manager (101) to regulate remote registry (105) access. In some embodiments, the remote registry access manager (101) runs on a first computer (102) and detects attempts by processes on the first computer (102) to remotely access a second computer's (103) registry (105). The remote registry access manager (101) determines whether attempts to remotely access the second computer's (103) registry (105) are legitimate. In responsive to determining that an attempt is legitimate, the remote registry access manager (101) allows the attempt to proceed. In responsive to determining that an attempt is not legitimate, the remote registry access manager (101) blocks the attempt.

[0011] In some embodiments, the remote registry access manager (101) runs on a computer (102) and detects remotely initiated attempts to access the computer's (102) registry (103). The remote registry access manager (101) determines whether remotely initiated attempts to access the computer's (102) registry (105) are legitimate or not legitimate, and allows or blocks the requests as appropriate.

[0012] The features and advantages described in this disclosure and in the following detailed description are not all-inclusive, and particularly, many additional features and advantages will be apparent to one of ordinary skill in the relevant art in view of the drawings, specification, and claims hereof. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter.

[0016] The Figures depict embodiments of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein.

[0017] FIG. 1 illustrates a high level overview of a system 100 for performing some embodiments of the present invention. A remote registry access manager 101 on a first computer 102 regulates attempts to remotely access a second computer's 103 registry 105. It is to be understood that although the remote registry access manager 101 is illustrated as a single entity, as the term is used herein a remote registry access manager 101 refers to a collection of functionalities which can be implemented as software, hardware, firmware or any combination of the three. Where a remote registry access manager 101 is implemented as software, it can be implemented as a standalone program, but can also be implemented in other ways, for example as part of a larger program, as a plurality of separate programs, or as one or more statically or dynamically linked libraries.

[0018] As illustrated in FIG. 1, in some embodiments the remote registry access manager 101 is instantiated in the form of at least one system call wrapper 107. The implementation mechanics of intercepting system calls 109 by overwriting pointers 111 in an interrupt vector table 113 and redirecting the pointers 111 to a system call wrapper 107 are known to those of ordinary skill in the relevant art.

[0019] In such embodiments, system calls 109 to access the registry 105 of a remote computer 103 are intercepted. For example, in current versions of Microsoft Windows NT®, the system call 109 that allows remote registry access is RegConnectRegistry( ) Of course, in various operating environments, the function that provides such access could have other names, or be instantiated in the form of multiple functions.

[0020] Because the relevant system call(s) 109 are intercepted, the remote registry access manager 101 can monitor and control attempts to remotely access the registries 105 of remote computers 103. In various embodiments, different criteria can be utilized to determine whether the access is to be allowed or blocked. In some embodiments, access will be allowed where a trust relationship has been established between the first (source) computer 102 and the second (target) computer 103. A more fine-grained security policy can be defined, either at a network or host level, for example to allow only certain computers, processes and/or users to remotely access the registry 103 database on certain other computers, to block certain computers 103, processes and/or users from having remote registry access to all or certain other computers (the black list concept) or to specifically allow certain computers, processes and/or users to have such access (the white list concept).

[0021] The security policy can further dictate certain dates and/or times at which specific types of remote access are to be allowed (or blocked). The security policy can further articulate specific numbers of times remote registry operations can be performed per day, per hour, by user, etc. The security policy can also control registry access at a registry key level, preventing specific (or all) types of access to certain sensitive registry keys, and/or allowing access to other keys as desired.

[0022] In some embodiments, if remote registry access is granted according to the security policy as described above, then the remote registry access manager 101 stores the registry key handle 115 returned by the intercepted system call 109 in a look-aside table 117 (or other suitable data structure). The remote registry access manager 101 then enforces the security policy against future local registry function calls 109 seeking to access the associated key through the stored handle 115. Because the key handle 115 will now appear local, the remote registry access manager 101 intercepts all registry access functions 109, and applies the security policy to any attempts to access remote keys through handles 115 stored in the look-aside table 117.

[0023] In some embodiments, the remote registry access manager 101 logs blocked remote registry access requests to an external data store 119. In some embodiments, a frequent number of blocked requests by a process (or multiple processes owned by a single user) will trigger the remote registry access manager 101 to adjudicate that the requesting process is malicious. In such embodiments, the remote registry access manager 101 can execute a malicious code processing engine (not shown) to block the operation of the malicious code, and remove it from the system. In other embodiments, the remote registry access manager 101 informs an appropriate system administrator or automatic malicious code manager, for example by e-mail or control signal.

[0024] In some embodiments, the remote registry access manager 101 logs allowed remote registry read and write operations to a data store 117, which can be used for security auditing. The remote registry access manager 101 can also monitor content read and/or written by allowed access operations in real time, and block operations that attempt to read or write suspected content (for example, attempts to write data having UNC path names to certain registry keys).

[0025] In other embodiments, the remote registry access manager 101 running on a computer 102 blocks non-legitimate remotely initiated attempts to access the registry 105 of that computer 102. As illustrated in FIG. 2, in some such embodiments, the remote registry access manager 101 is instantiated as at least one system call wrapper 107, wrapping registry access system calls 109.

[0026] In various 32 bit versions of Windows®, all remote access to the registry 105 goes through a remote registry server 201. Therefore, registry access calls 109 made by the remote registry server 201 are of interest to the remote registry access manager 101. In Windows NT®, the remote registry server 201 runs in user space 203, and can be found under: \\hkey_local_machine\system\cuerrentcontrolset\servicers\remoteregistry \parameters ServiceDll=%systemroot%\system32\regsvc.dll Of course, in other operating environments, the remote registry server 201 could reside in another dynamic link library, run in kernel space 205, or be implemented in another way. In any case, in any environment in which all remote access to the registry 105 goes through the remote registry server 201, the remote registry access manager 101 can intercept registry access calls 109 and identify those made by the remote registry server 201. By controlling the remote registry server's 201 access to the registry 105, the remote registry access manager 101 can enforce the desired security policy, as described above, in conjunction with FIG. 1. The remote registry access manager can also log blocked remote registry access attempts, use multiple blocked attempts to identify the process attempting the access as being malicious and inform a trusted process on the requesting computer (or elsewhere on the network) or a human user of the identification of the malicious code. The remote registry access manager 101 can also log allowed remoter registry access attempts, and monitor them for suspicious content as described above.

[0027] Turning now to FIG. 3, in some embodiments the remote registry access manager 101 is instantiated within a file system filter driver 301. The implementation mechanics of file system filter drivers 301 are known to those of ordinary skill in the relevant art.

[0028] In Microsoft Windows® NT and related versions of Microsoft Windows®, the remote registry access protocol is implemented as a named pipe file 303 with the name \\.\pipe\winreg that is transferred through the CIFS (SMB) protocol. The protocol is implemented through the byte streams written into the \winreg named pipe 303. Inside the Windows kernel 205, srv.sys 305 issues file system IO requests 307 to the named pipes file system npfs.sys 309 with the file name equal to \winreg. Therefore, the remote registry access manager 101 can be installed in the form of a file system filter driver 301 that attaches to the named pipes file system 309 and filters the file I/O traffic that goes to \winreg. By filtering all such traffic, the remote registry access manager 101 can watch all attempts to remotely access the registry 105, and enforce the security policy as described above. The remote registry access manager 101 can also log and manage allowed and blocked requests as described above, in conjunction with FIG. 2.

[0029] The Winreg (remote registry access) protocol is known to those of ordinary skill in the relevant art, and is documented in different sources, such as the Samba project (www.samba.org) and the book DCE/RPC over SMB: Samba and Windows NT Domain Internals, Luke Leighton, Que, Dec. 10, 1999.

[0030] In another embodiment, the remote registry access manager 101 hooks the calls that srv.sys 305 makes the 10 manager 311 to access the \\.\pipe\winreg file. This could be done by hooking the Portable Executable .IMPORTS table (not shown) of srv.sys 305 in memory, and filtering the file I/O request calls 307.

[0031] Alternatively, the remote registry access manager 101 can be implemented as a user mode 203 netbios loopback server 313. The implementation mechanics of loopback servers 313 are known to those of ordinary skill in the relevant art. Known examples include the Samba approach (www.samba.org) or the IBM AFS (www.afs.org) loopback server on Windows 2000®.

[0032] In loopkback server 313 based embodiments, the netbios loopback server 313 filters access requests to the \\.\pipe\winreg named pipe 303, and decodes the byte stream as defined by the remote registry access protocol. Thus, the remote registry access manager 101 can control remote registry access as described above.

[0033] As will be understood by those familiar with the art, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Likewise, the particular naming and division of the modules, managers, features, attributes, methodologies and other aspects are not mandatory or significant, and the mechanisms that implement the invention or its features may have different names, divisions and/or formats. Furthermore, as will be apparent to one of ordinary skill in the relevant art, the modules, managers, features, attributes, methodologies and other aspects of the invention can be implemented as software, hardware, firmware or any combination of the three. Of course, wherever a component of the present invention is implemented as software, the component can be implemented as a script, as a standalone program, as part of a larger program, as a plurality of separate scripts and/or programs, as a statically or dynamically linked library, as a kernel loadable module, as a device driver, and/or in every and any other way known now or in the future to those of skill in the art of computer programming. Additionally, the present invention is in no way limited to implementation in any specific programming language, or for any specific operating system or environment. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.