Hi all
I have just run 'binwalk' to see if there are any differences between the old firmware and the new and it appears as though the Dahua have started to encrypt there images. Please find differences between old and new.
New:
binwalk romfs-x.squashfs.img
DECIMAL HEXADECIMAL DESCRIPTION
--------------------------------------------------------------------------------
0 0x0 uImage header, header size: 64 bytes, header CRC: 0x72AE579C, created: 2019-12-21 01:45:25, image size: 41054208 bytes, Data Address: 0xA0F00000, Entry Point: 0xA4500000, data CRC: 0x1155415A, OS: Linux, CPU: ARM, image type: OS Kernel Image, compression type: gzip, image name: "NVR4X-S2"
3934067 0x3C0773 Zlib compressed data, best compression
6646576 0x656B30 Zlib compressed data, best compression
6647029 0x656CF5 Zlib compressed data, best compression
6647222 0x656DB6 Zlib compressed data, best compression
6655178 0x658CCA Zlib compressed data, best compression
6658199 0x659897 Zlib compressed data, best compression
6658986 0x659BAA Zlib compressed data, best compression
6659138 0x659C42 Zlib compressed data, best compression
6659179 0x659C6B 7-zip archive data, version 0.3
18263854 0x116AF2E 7-zip archive data, version 0.4
21253852 0x1444EDC 7-zip archive data, version 0.4
21966244 0x14F2DA4 mcrypt 2.5 encrypted data, algorithm: "~_xa", keysize: 26871 bytes, mode: "2",
22251354 0x153875A 7-zip archive data, version 0.4
24559037 0x176BDBD Zlib compressed data, best compression
25819743 0x189FA5F Zlib compressed data, best compression
34672141 0x2110E0D 7-zip archive data, version 0.3
41013320 0x271D048 Zlib compressed data, best compression
41015297 0x271D801 Zlib compressed data, best compression
41019514 0x271E87A Zlib compressed data, best compression
41025607 0x2720047 Zlib compressed data, best compression
41027481 0x2720799 Zlib compressed data, best compression
41033019 0x2721D3B Zlib compressed data, best compression
41038786 0x27233C2 Zlib compressed data, best compression
41044255 0x272491F Zlib compressed data, best compression
41046098 0x2725052 Zlib compressed data, best compression
Old:
binwalk romfs-x.squashfs.img
DECIMAL HEXADECIMAL DESCRIPTION
--------------------------------------------------------------------------------
0 0x0 uImage header, header size: 64 bytes, header CRC: 0x8C2162AF, created: 2019-08-09 03:56:17, image size: 41463808 bytes, Data Address: 0xA0F00000, Entry Point: 0xA4500000, data CRC: 0x8A9829AD, OS: Linux, CPU: ARM, image type: OS Kernel Image, compression type: gzip, image name: "NVR4X-S2"
64 0x40 Squashfs filesystem, little endian, version 4.0, compression:xz, size: 41459876 bytes, 2660 inodes, blocksize: 131072 bytes, created: 2019-08-09 03:56:17
Maybe this can shed some light why the files aren't being extracted.