Trojan.FBSpammer
ThreatDown is now the name of the Malwarebytes line of business products. References to Malwarebytes below reflect the amazing technology used to first identify the threat.
Short bio
Trojan.FBSpammer is Malwarebytes’ detection name for a family of Firefox extensions that are designed to spam Facebook groups.
Type of infection
Trojan.FBSpammer is a Firefox extension that joins multiple Facebook groups and starts posting in them on behalf on the victim. Trojan.FBSpammer is installed from websites that offer it as a Flash update.
Malicious behavior
Users of affected systems may notice a Firefox extension that is called Page Update and the corresponding .xpi file has a random name consisting of capital characters and underscores.
Users may also notice posts made on their behalf on Facebook groups they did not join themselves.
Protection
Both the Web protection module and the Malwarebytes browser extension block the websites pushing this malicious extension.
Home remediation
You can use the Malwarebytes Anti-Malware Nebula console to scan endpoints.
Choose the Scan + Quarantine option. Afterwards you can check the Detections page to see which threats were found.
On the Quarantine page you can see which threats were quarantined and restore them if necessary.