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Detecting USB Drive
To detect whether a program is running in a sandbox environment, malware can look for the presence of USB drives. Many sandboxes do not have USB ports or do not allow access to USB drives, and detecting the absence of USB drives can help identify whether the program is being run in a sandbox.
Read moreCloseHandle, NtClose
When a process is debugged, calling NtClose or CloseHandle with an invalid handle will generate a STATUS_INVALID_HANDLE exception.
The exception can be cached by an exception handler. If the control is passed to the exception handler, it indicates that a debugger is present.
Read moreHeap Flag
ProcessHeap is located at 0x18 in the PEB structure. This first heap contains a header with fields used to tell the kernel whether the heap was created within a debugger. The heap contains two fields which are affected by the presence of a debugger. These fields are Flags and ForceFlags.
The values of Flags and ForceFlags are normally …
NtGlobalFlag
The information that the system uses to determine how to create heap structures is stored at an undocumented location in the PEB at offset 0x68. If the value at this location is 0x70, we know that we are running in a debugger.
The NtGlobalFlag field of the Process Environment Block (0x68 offset on 32-Bit and 0xBC on …
GetTickCount
This is typical timing function which is used to measure time needed to execute some function/instruction set. If the difference is more than fixed threshold, the process exits.
GetTickCount reads from the KUSER_SHARED_DATA page. This page is mapped read-only into the user mode range of the virtual address and read-write in the kernel range. The system clock tick updates …
Unhandled Exception Filter
An application-defined function that passes unhandled exceptions to the debugger, if the process is being debugged. Otherwise, it optionally displays an application error message box and causes the exception handler to be executed.
If an exception occurs and no exception handler is registered, the UnhandledExceptionFilter function will be called. It is possible to register a custom unhandled exception filter …
INT3 Instruction Scanning
Instruction INT3 is an interruption which is used as Software breakpoints. These breakpoints are set by modifying the code at the target address, replacing it with a byte value 0xCC (INT3 / Breakpoint Interrupt).
The exception EXCEPTION_BREAKPOINT (0x80000003) is generated, and an exception handler will be raised. Malware identify software breakpoints by scanning for the byte 0xCC in the …
Custom Encoding
Malware often uses custom encoding schemes to conceal their payloads and avoid detection. These custom schemes can be full custom layers, or they can be variations of known algorithms such as XOR or Base64. Using custom encoding schemes allows malware to encode their payloads in a unique way that can be difficult for security tools and forensic investigators to detect.
… Read moreIndicator Removal: Clear Windows Event Logs
![Defense Evasion [Mitre] icon](/media/2024/04/08/icons8-burglar.svg){kind=small}
Event logging is a process that records important software and hardware events from various sources and stores them in a centralized location called an event log. This service is commonly used by applications and operating systems to track and troubleshoot issues, and can be a valuable tool for forensic investigations.
Event logs can provide valuable information about the actions …
Read moreThermal Zone Temperature
The temperature sensor is used to know the current temperature of a machine. In a non-virtualized environment, the function returns valid support and output like: "25.05 C: 77.09 F: 298.2K". But for a fully virtualized environment, the return is "MSAcpi_ThermalZoneTemperature not supported" because this feature is not supported on virtualized processors.
Interestingly, this method is not valid. Not all …
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