Third-party (i.e. community, not NPM-maintained) packages hosted by NPM found to have reverse-shell, data mining functionality present.

From the original article [1]:

NPM has removed multiple packages hosted on its repository this week that established connection to remote servers and exfiltrated user data.

These 4 packages had collected over 1,000 total downloads over the course of the last few months up until being removed by NPM yesterday.

The four packages are:

plutov-slack-client - claims to be a "Node.JS Slack Client" according to the information in the manifest 
nodetest199 - no description
nodetest1010 - no description
npmpubman - claims to be "a simple implementation about Linux shell login" according to the information in the manifest 

Impact

The overall impact is not reported at this time. The number of unique downloads (for an NPM package) is somewhat low, i.e.

These 4 packages had collected over 1,000 total downloads over the course of the last few months up until being removed by NPM yesterday.

The potential damage such exploits/vulnerabilities could generate is, in general severe (i.e. remote control, data access/mining). The offending packages have since been removed by NPM.

Type of compromise

These malicious packages fall within a development tooling compromise. The first three packages appear to allow a specific attacker to gain remote control over the victim’s local machine. The fourth package appears to harvest user data (i.e. files) from the local machine and then upload them to a remote server (presumably controlled by the attacker).

References.

1. “NPM nukes NodeJS malware opening Windows, Linux reverse shells”, Ax Sharma, <https://www.bleepingcomputer.com/news/security/npm-nukes-nodejs-malware-opening-windows-linux-reverse-shells/>, last accessed 2020-10-21.