[update]: undeath was once again faster to answer the questions. he of course gives very good advice so read his suggestions too. I will leave my reply here anyways, maybe it adds just a little bit more info here and there to be worth keeping it. probably not because his answers are always on point 
I'm not sure what you mean by "the command doesnt seem to allow dd to read from the hidden partition".
dd is able to read any bytes that are available on disks.
If you mean that your operating system doesn't allow reading with unpriviledged user accounts, then you probably need to be an administrator etc.
What operating system do you use ? windows ? if you really have problems with the dd.exe tool, you could always try to use a linux live cd/iso/image and use the dd with sudo etc.
regarding your second question about how to use different attacks with hashcat, hashcat has a -a (or long --attack-mode) option (read the output of hashcat --help and/or faq/wiki) with whch you can try different attacks.
if your list of password candidates is quite small, you could precompute them and use a "simple" dictionary attack (-a 0 without rules), but as soon as the dictionary would be several MB/GB I would suggest using -a 1 / -a 6 / -a 7 or -a 0 together with rules (-r).
It all depends on your password pattern.
If you are sure that it's exactly 3 dicts combined (dict1.txt containing the aaa passwords, dict2.txt containing the bbb passwords and dict3 containing the ccc passwords) and you know that they do not overlap and the password can't be aaaaaabbb or ccccccccc etc, you could use combinator3 from hashcat-utils to pre-compute the dicts or use somethng like this:
update2: [added / corrected the combinator3 commands, dicts do not overlap, no common words]
if you want to allow the same password occuring multiple times i.e. with overlaps in the dicts, like aaaaaaaaa:
to pre-compute a concatenated dict (dict1_and_dict2.txt) and save it on disk and afterwards run hashcat like this:
where 137XY needs to be adjusted depending on your VeraCrypt settings (for instance -m 13711 for VeraCrypt ripemd160 and 512 bit AES)
I'm not sure what you mean by "the command doesnt seem to allow dd to read from the hidden partition".
dd is able to read any bytes that are available on disks.
If you mean that your operating system doesn't allow reading with unpriviledged user accounts, then you probably need to be an administrator etc.
What operating system do you use ? windows ? if you really have problems with the dd.exe tool, you could always try to use a linux live cd/iso/image and use the dd with sudo etc.
regarding your second question about how to use different attacks with hashcat, hashcat has a -a (or long --attack-mode) option (read the output of hashcat --help and/or faq/wiki) with whch you can try different attacks.
if your list of password candidates is quite small, you could precompute them and use a "simple" dictionary attack (-a 0 without rules), but as soon as the dictionary would be several MB/GB I would suggest using -a 1 / -a 6 / -a 7 or -a 0 together with rules (-r).
It all depends on your password pattern.
If you are sure that it's exactly 3 dicts combined (dict1.txt containing the aaa passwords, dict2.txt containing the bbb passwords and dict3 containing the ccc passwords) and you know that they do not overlap and the password can't be aaaaaabbb or ccccccccc etc, you could use combinator3 from hashcat-utils to pre-compute the dicts or use somethng like this:
update2: [added / corrected the combinator3 commands, dicts do not overlap, no common words]
Code:
combinator3.bin dict1.txt dict2.txt dict3.txt > dict.txt
combinator3.bin dict1.txt dict3.txt dict2.txt >> dict.txt
combinator3.bin dict2.txt dict1.txt dict3.txt >> dict.txt
combinator3.bin dict2.txt dict3.txt dict1.txt >> dict.txt
combinator3.bin dict3.txt dict1.txt dict2.txt >> dict.txt
combinator3.bin dict3.txt dict2.txt dict1.txt >> dict.txtif you want to allow the same password occuring multiple times i.e. with overlaps in the dicts, like aaaaaaaaa:
Code:
hashcat --stdout -a 1 -o dict1_and_dict2.txt dict.txt dict.txtCode:
hashcat -m 137xy -w 3 -a 1 hashcat_ripemd160_AES_hidden.tc dict1_and_dict2.txt dict.txtwhere 137XY needs to be adjusted depending on your VeraCrypt settings (for instance -m 13711 for VeraCrypt ripemd160 and 512 bit AES)