Howard Oakley solves your Mac and iOS issues
QMy MacBook Air with 8GB of memory has been running out of that resource lately; Activity Monitor shows an item called Installer keeps popping up to consume large amounts of it. I don't have anything installed that would behave like that. What’s going on?
AAlthough macOS makes best use of physical memory, it shouldn't be going into the red like this, and you are rightly suspicious of any periodic process consuming lots of memory.
A good way to identify what’s responsible and check if it's above board is to inspect it using TaskExplorer (free, objective-see.com). This links into the VirusTotal database to determine whether a task might be malware, which seems highly likely in your case.
Anything running periodically is probably doing so by means of an installed LaunchAgent or LaunchDaemon, possibly located in LaunchAgents or LaunchDaemons in the Library folder at the top of your startup disk or in your Home folder, or hidden somewhere else. If the task isn’t malware, identify the culprit and uninstall it if you can, and seek advice from its publisher.
If the misbehaving task turns out to be adware or malware, remove it using a tool such as MalwareBytes (free, malwarebytes. com). From the behaviour you describe, the culprit may well be one of several variants of the InstallMac malware. That can be removed manually, but the process is quite fiddly and prone to error. Once removed, check again using TaskExplorer. TaskExplorer, which is free for personal use, can identify whether a task on your Mac is known malware.