Group policy refresh behaviour

The default refresh interval for group policy is 90 minutes with an additional 0 to 30 minute random offset. You can also manually trigger a policy refresh by running gpupdate. Note: The refresh interval on domain controllers is only 5 minutes (with no offset). The refresh process checks if any…

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Collect logs from multiple servers with PowerShell

The code in this post is rather simplistic, and very specific to a particular task, but some of the concepts may prove useful to others. The requirement was to copy a specific log file from a large number of servers to a central management server, search the copied logs for…

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Right-to-left-override unicode character

Unicode is a character encoding standard that supports most of the world's written languages. To support such a broad character set with a standard US keyboard, individual Unicode characters can be entered on a Windows computer by holding down the Alt key, and then entering the numeric code of the…

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Changing window titles using PowerShell

Toward the end of my previous post on using SetWindowsHookEx to create global system hooks, I alluded to my failed attempt at changing window titles with PowerShell by hooking WM_SETTEXT messages. There is, however, another way to achieve this goal, albeit, far less elegant. Instead of proactively intercepting the…

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Creating a key logger via a global system hook using PowerShell

Applications in Microsoft Windows are event-driven. The operating system generates messages in response to various conditions (e.g. the user moves the mouse, or clicks a button), and these messages are sent to application windows, where they are processed by a message handler. An application can also generate its own…

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NTFS alternate data streams

The data within a file on an NTFS partition is stored in an element called a stream. Each file has a mandatory "unnamed" stream, but alternate streams may also be created. Let's create a simple text file: echo Hello > hello.txt A quick check - dir hello.txt -…

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