This fork aims to continue the work of the heavily modified version of Cuckoo Sandbox provided under the GPL by Optiv, Inc.
It offers a number of advantages over the upstream Cuckoo:
- Fully-normalized file and registry names
 - 64-bit analysis
 - Handling of WoW64 filesystem redirection
 - Many additional API hooks
 - Service monitoring
 - Correlates API calls to malware call chains
 - Ability to follow APC injection and stealth explorer injection
 - Pretty-printed API flags
 - Per-analysis Tor support
 - Over 150 new signature modules (over 75 developed solely by Optiv)
 - Anti-anti-sandbox and anti-anti-VM techniques built-in
 - More stable hooking
 - Ability to restore removed hooks
 - Greatly improved behavioral analysis and signature module API
 - Ability to post comments about analyses
 - Deep hooks in IE's JavaScript and DOM engines usable for Exploit Kit identification
 - Automatic extraction and submission of interesting files from ZIPs, RARs, RFC 2822 emails (.eml), and Outlook .msg files
 - Direct submission of AV quarantine files (Forefront, McAfee, Trend Micro, Kaspersky, MalwareBytes, MSE/SCEP, and SEP12 formats currently supported)
 - Automatic malware classification by Malheur
 - Significant contributions from Jeremy Hedges, William Metcalf, and Kevin Ross
 - Hundreds of other bugfixes
 
For more information on the initial set of changes, see: http://www.accuvant.com/blog/improving-reliability-of-sandbox-results
If you want to contribute to development, feel free to submit a pull request.