Adversaries may modify file time attributes to hide new or changes to existing files. Timestomping is a technique that modifies the timestamps of a file (the modify, access, create, and change times), often to mimic files that are in the same folder. This is done, for example, on files that have been modified or created by the adversary so that they do not appear conspicuous to forensic investigators or file analysis tools.
APT32 has used scheduled task raw XML with a backdated timestamp of June 2, 2016. The group has also set the creation time of the files dropped by the second stage of the exploit to match the creation time of kernel32.dll. Additionally, APT32 has used a random value to modify the timestamp of the file storing the clientID.
Several Lazarus Group malware families use timestomping, including modifying the last write timestamp of a specified Registry key to a random date, as well as copying the timestamp for legitimate .exe files (such as calc.exe or mspaint.exe) to its dropped files.
This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.
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Forensic techniques exist to detect aspects of files that have had their timestamps modified.  It may be possible to detect timestomping using file modification monitoring that collects information on file handle opens and can compare timestamp values.