# Testing an issue with case-insensitive enabled

Disclaim: better visualized using a markdown render

Note: This documentation was made as an effort to reproduce the PoC for CVE-2024-32002
in a Linux system. Check [1] for more detail about the PoC.

## Create a loop device

Create a file to be your block device

```bash
$ dd if=/dev/zero of=filename bs=1024 count=51200
```

After the filename was created with blocks of 1024 size in total of ~51M.

Now check which loop device is available:

```bash
$ losetup -f
# output example: /dev/loop19
```

Create the block device with the available loop device

```bash
losetup /dev/loop19 filename
# where filename is the block file you created using dd
```

## Case-insensitive

This feature was added in kernel 5.2. If you want to be sure your system supports it, try this:

```bash
cat /sys/fs/ext4/features/casefold
# ouput: supported
```

Once checked that it is supported now you need to mount the file system with that feature.

```bash
mkfs -t ext4 -O casefold /dev/loop19

# create using mkdir the  poc directory where you'll mount it in /mnt/poc
# remember to set the permissions if you don't want to use root all the time
# chown -R your_user:your_user_group poc
# e.g: chown -R leosilva:leosilva poc

mount -t ext4 /dev/loop19 /mnt/poc

# check if was mounted
df -h /dev/loop19

# check that device/fs supports case insensitive looking for
# Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery extent 64bit flex_bg casefold <--
sudo tune2fs -l /dev/loop19


```

Now you have a folder set with that file system mounted. To enable case insensitive in a folder
you need to:

```bash
chattr +F directory
```

If you want to check which directory is case-insensitive supported:
```bash
lsattr .
# output: ----------------F--- directory
```

## References

[1] https://amalmurali.me/posts/git-rce/
[2] https://www.collabora.com/news-and-blog/blog/2020/08/27/using-the-linux-kernel-case-insensitive-feature-in-ext4/
[3] https://dzone.com/articles/loop-device-in-linux