Rainbow Crackalack project produces open-source code to generate rainbow tables as well as use them to look up password hashes. While the current release only supports NTLM, future releases aim to support MD5, SHA-1, SHA-256, and possibly more. Both Linux and Windows are supported!
Rainbow tables went out of style a few years ago when GPU-accelerated password cracking became popular. With tools like hashcat, it no longer made sense to invest the effort to obtain the existing obsolete tables. Furthermore, no GPU-accelerated open-source tools existed to create new tables with. For these reasons, the world of rainbow tables was forgotten by the infosec community.
However, rule-based cracking and rainbow table cracking were never exclusive strategies. They were (and still are, in fact), complementary. Rules are great at finding patterns, which are commonly set by users; rainbow tables are effective against fully random passwords, which can exist for highly sensitive accounts.
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Examples
Generating NTLM 9-character tables
The following command shows how to generate a standard 9-character NTLM table:
# ./crackalack_gen ntlm ascii-32-95 9 9 0 803000 67108864 0
The arguments are designed to be comparable to those of the original (and now closed-source) rainbow crack tools. In order, they mean:
| Argument | Meaning |
|---|---|
| ntlm | The hash algorithm to use. Currently only “ntlm” is supported. |
| ascii-32-95 | The character set to use. This effectively means “all available characters on the US keyboard”. |
| 9 | The minimum plaintext character length. |
| 9 | The maximum plaintext character length. |
| 0 | The reduction index. Not used under standard conditions. |
| 803000 | The chain length for a single rainbow chain. |
| 67108864 | The number of chains per table (= 64M) |
| 0 | The table part index. Keep all other args the same, and increment this field to generate a single set of tables. |
Table lookups against NTLM 8-character hashes
The following command shows how to look up a file of NTLM hashes (one per line) against the NTLM 8-character tables:
# ./crackalack_lookup /export/ntlm8_tables/ /home/user/hashes.txt
The NVIDIA GTX & RTX lines of GPU hardware has been well-tested with the Rainbow Crackalack software, and offer an excellent price/performance ratio. Specifically, the GTX 1660 Ti or RTX 2060 are the best choices for building a new cracking machine. This document contains the raw data that backs this recommendation.
However, other modern equipment can work just fine, so you don’t necessarily need to purchase something new. The NVIDIA GTX and AMD Vega product lines are still quite useful for cracking!
- v1.0: June 11, 2019: Initial revision.
- v1.1: August 8, 2019: massive speed improvements (credit Steve Thomas), finalization of NTLM9 spec, bugfixes.
A 64-bit Windows build can be achieved on an Ubuntu host machine by installing the following prerequisites:
# apt install mingw-w64 opencl-headers
Then starting the build with:
# make clean; ./make_windows.sh
Credit: Joe Testa
