Well, I guess if we agree that the algorithm is MD5(MD5_raw ($salt) . MD5_raw ($pass)) you could convert those hashes to just MD5 ($salt_new . MD5_raw ($pass)) where $salt_new is the precomputed MD5 digest.
Since hashcat currently does not support the MD5_raw () part for -m 3710, you could just patch the kernels (OpenCL/m03710_a0.cl for -a 0, OpenCL/m03710_a1.cl for -a 1 and OpenCL/m03710_a3.cl for -a 3) as simple as this:
removing the uint_to_hex_lower8 () function calls (https://github.com/hashcat/hashcat/blob/...#L182-L205) and replacing the resulting buffer (w0_t[x] - w3_t[x]) with the raw output of MD5 (a, b, c, d) + setting 0x80 correctly (w1_t[0] = 0x80) + updating the final length https://github.com/hashcat/hashcat/blob/..._a3.cl#L64 (should be 16 + salt_len) ... these changes need to be done for all places where you find uint_to_hex_lower8 () calls and "const u32 pw_salt_len".
This should be very trivial. You just need to make sure that:
1. you have no cached kernels (in the kernels/ folder), remove it whenever you make changes to the kernels
2. that you carefully test your changes with both single and multiple hash list + all attack types (a0, a1, a3)
3. that you remember that you made these changes and possibly rename the hashcat root folder name accordingly so you do not confuse your modified 3710 hashcat "installation" with an unmodified one (because your new 3710 kernels now would not crack normal 3710 hashes anymore!)
4. that you converted the usernames correctly to their MD5 counterpart and that you do not forget to always use --hex-salt!
Since hashcat currently does not support the MD5_raw () part for -m 3710, you could just patch the kernels (OpenCL/m03710_a0.cl for -a 0, OpenCL/m03710_a1.cl for -a 1 and OpenCL/m03710_a3.cl for -a 3) as simple as this:
removing the uint_to_hex_lower8 () function calls (https://github.com/hashcat/hashcat/blob/...#L182-L205) and replacing the resulting buffer (w0_t[x] - w3_t[x]) with the raw output of MD5 (a, b, c, d) + setting 0x80 correctly (w1_t[0] = 0x80) + updating the final length https://github.com/hashcat/hashcat/blob/..._a3.cl#L64 (should be 16 + salt_len) ... these changes need to be done for all places where you find uint_to_hex_lower8 () calls and "const u32 pw_salt_len".
This should be very trivial. You just need to make sure that:
1. you have no cached kernels (in the kernels/ folder), remove it whenever you make changes to the kernels
2. that you carefully test your changes with both single and multiple hash list + all attack types (a0, a1, a3)
3. that you remember that you made these changes and possibly rename the hashcat root folder name accordingly so you do not confuse your modified 3710 hashcat "installation" with an unmodified one (because your new 3710 kernels now would not crack normal 3710 hashes anymore!)
4. that you converted the usernames correctly to their MD5 counterpart and that you do not forget to always use --hex-salt!