Recently, Microsoft warned users about compatibility issues with applications using some non-ASCII characters in names of their registry keys. According to Microsoft:
Compatibility issues have been found between apps using some non-ASCII characters in their registry keys or subkeys and Windows 11. Affected apps might be unable to open and might cause other issues or errors in Windows, including the possibility of receiving an error with a blue screen. ImportantAffected registry keys with non-ASCII characters might not be able to be repaired.
Although NTFS has been designed with case-sensitivity in mind, it’s used mostly in the case-insensitive environment. One can natively store, within the same directory, two or more files with their names differing only in case, but Windows-based tools won’t deal with them correctly. To provide true case-sensitivity, Microsoft implemented an additional layer, per-directory case-sensitivity, as described here, here, and here.
But there are several issues with usual, case-insensitive, operations…
Windows Explorer displays $STANDARD_INFORMATION timestamps.
A file with a single name has 12 timestamps: 4 timestamps come from the $STANDARD_INFORMATION attribute in a file record, 4 timestamps come from the $FILE_NAME attribute in the same file record, and 4 timestamps come from the $FILE_NAME attribute in an index record ($I30) of a parent directory.
If there is a short file name together with a long one, the number of timestamps is 20 (8 more timestamps come from two additional $FILE_NAME attributes in a file record and in an index record of a parent directory respectively).
You can also add an UUIDv1 timestamp from the $OBJECT_ID attribute, timestamps recorded in the USN journal and in the $LogFile journal. But these aren’t always present.
Things are more complicated with timestamps displayed by Windows Explorer.
Some virtualization software allows a user to launch a virtual machine with its real-time clock starting ticking from custom base time. For example, a user can launch a virtual machine with base time set to 2020-12-31 23:59:59 UTC, the real-time clock inside this virtual machine will start ticking from that value, regardless of the current date and time set on a host. I use this feature to test artifacts without telling Windows to move the clock.
However, if you decide to go back and restart the same virtual machine without defining custom base time (also without Internet access and without changing the date and time settings in the running operating system), the guest operating system won’t necessary use the current date and time (as set on a host). In some cases, it will continue to run using the previously defined (future) date.
Some editions of Windows 10 are capable of running Windows containers using Docker. Each Docker container is based on an immutable image with all modified data stored in an overlay. When a Windows container is used, the system has to record modifications affecting both the file system and the registry.
In 2016, Microsoft implemented new functionality called layered keys to allow programs access a merged view of keys and values from two or more registry hives! Now, this functionality is utilized by Docker…
This was already described here, but let’s revisit the topic.
Let’s install the Windows Server 2016 operating system on a machine, install all available updates, configure the machine as a domain controller and an RDP server, create several domain user accounts. Then, create a shadow copy and delete it. After some time, create a new shadow copy and keep the machine running for a while, then create another shadow copy. How many shadow copies are there? Two (the oldest one was deleted, thus not counted).
Let’s simulate a remote attack against this domain controller. The attack involves dumping the ntds.dit file. In order to copy that file, I will use an approach outlined in this guide: create a shadow copy, copy the ntds.dit file from it, then delete this shadow copy to remove my tracks (all these actions are performed over an RDP connection, just like a real attack).
Finally, let the system run for some time and occasionally create two more shadow copies. How many shadow copies are there now?
Storage Reserve is a relatively new feature that keeps some disk space in a system volume available for downloading and installing Windows updates. Its implementation is simple – the current amount of free space visible to applications is decreased, so the “no space left” condition occurs before the space is really exhausted.
Take a look at these screenshots:
Both of them illustrate the same drive. On the first screenshot, this drive is attached to a Windows 8.1 installation. On the second one, the same drive (actually, exactly the same image of a virtual drive) is attached to a Windows 10 “20H1” installation. And the amount of free space reported by these operating systems is different!
However unexpectedly when I ran the Encase Recover Folders feature across the HarddiskShadowcopy5 volume it found traces of the Sony folder and in fact many other files post dating the creation of the shadow copy.
The Encase Recover Folders feature parses unallocated clusters looking for folder metadata. It seems that it found data in unallocated clusters relating to the current volume. Therefore I believe that any deleted but recoverable data within the shadow copies needs to be treated with caution.
Null bytes instead of real data can be returned as well.
There is no way to distinguish between “real” and “fake” unallocated data when reading a shadow copy using the device exposed by the volsnap driver (“HarddiskVolumeShadowCopy<N>“).