Category: x64

Recovering Deleted Windows Files [Breakdown and Theory]

When you delete a file on Windows, specifically Windows 10 Professional x64, it is removed from the user’s view and placed in the recycle bin for permanent deletion. Once that permanent deletion is performed, some ask the question “is the file really gone?” The answer is no, not immediately, and even after permanent deletion it’s […]

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Structure of Security Identifiers

Recently a friend of mine asked about an unknown user account associated with all files, new or old, with an unknown SID (security identifier) attached. I noted that this is common when local machines have had accounts that have since been removed. However, he then asked about the structure of that number so I figured […]

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Usermode Debugger Check Prevention

It’s easy enough to use OllyDbg or any other debugger to bypass debugger checks, but any sort of anti-debugging technique that utilizes the time stamp counter such as QueryPerformanceCounter, GetTickCount, and others, can be bypassed by setting the 2nd bit in control register 4 (CR4) which disables the TimeStamp Counter from working for applications operating […]

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Breaking Down System Routines #2 [NtQuerySystemInformation]

System Routine Overview NtQuerySystemInformation¬†is a system routine that gathers system information specific to the class value provided. During this breakdown, we’ll look at it in much more depth because, like the previous system routine documented, it’s just a wrapper for an internal kernel routine that actually gathers the system information. However, the internal routine it […]

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Breaking Down System Routines #1 [NtQuerySection]

NtQuerySection is a system routine for the Windows operating system that queries information related to a section object and provides the information regarding that object by filling a buffer passed to the function. As an important note, all disassembly and reversing took place on Windows 10 x64 Professional. It requires 4 arguments, 5 if you […]

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Using Flags of RTL_USER_PROCESS_PARAMETERS for Anti-Debugging

OverviewThere are various flags in the PEB associated with a specific process such as the CrossProcessFlags, the BitField (4th member of the PEB), AppCompatFlags, and so forth. I’d always tried looking for differences in the flags when operating in a standard runtime environment vs. a debugged runtime environment and after many failed attempts to find […]

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