noch lab

1. Overview Prefetch is artifact that exists in Windows. This artifact records program execution files read by that program in 10 seconds. Prefetch is one of the most well-known artifacts, but its recording mechanism is very complex as follows.　(This is an simplified version, not the whole thing.) I reversed the kernel to look for something interesting in the data related to prefetch. However, I could not find any incident response usable data. Now that I understand the mechanisms involved in prefetch, I leave this blog as a note. ・Same executable but different prefetch conditions ・High probability bypass prefetch 2. Same executable but different prefetch conditions Generally, prefetch is created for each executable file path. This is handled internally as the following NT kernel path. If the hashes of this path are the same, they are written to the same prefetch. \Device\HarddiskVolume2\Windows\System32\cmd.exe However, there are a few exceptions. You will see a l...

1. Overview ShimCache (AppCompatCache) is artifact that exists in Windows SYSTEM registry. This artifact records program execution but not execution time. Nevertheless, it is valuable artifact on Windows Server hosts where prefetch is not recorded by default or Windows hosts where prefetch has been removed. This article describes the following topics. ・Information in ShimCache (Forensics) ・Reverse engineering on ShimCache mechanism (Redteaming) 2. Information in ShimCache Shimcache is recorded under following subkey. HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Session Manager\AppCompatCache Shimcache data is binary format and composed of 52 byte header and multiple entries in Windows 10 (ver 2004). The format of the entry is as follows. Field Type Offset Description Signature DWORD 0x00 31 30 74 73 (10ts) CRC32 Hash DWORD 0x04 Entry Size DWORD 0x08 Path Size WORD 0x0C Path field's data length Path WString 0x0E PE file path Modified Time FILETIME NTFS $SI mo...