Researchers observed four attacks targeting financial institutions in West Africa since at least mid-2017. Some of the tools used cost as little as $25, although the use of the more expensive commercial penetration testing tool Cobalt Strike was also observed. In one of the attacks, the threat actor used NanoCore trojan along with PsExec, a legitimate network administration tool, and delivered the malware via phishing emails. The author of NanoCore was arrested in early 2017 and sentenced to 33 months in prison and two years of supervised release.
Source: https://www.bleepingcomputer.com/news/security/banks-in-west-africa-hit-with-off-the-shelf-malware-free-tools/