eradicating-malware-from-infected-systems

name	eradicating-malware-from-infected-systems
description	Systematically remove malware, backdoors, and attacker persistence mechanisms from infected systems while ensuring complete eradication and preventing re-infection.
domain	cybersecurity
subdomain	incident-response
tags	["incident-response","eradication","malware-removal","persistence","dfir"]
mitre_attack	["T1547","T1053","T1543","T1574"]
version	1.0
author	mahipal
license	Apache-2.0
nist_csf	["RS.MA-01","RS.MA-02","RS.AN-03","RC.RP-01"]

Eradicating Malware from Infected Systems

When to Use

• Malware infection confirmed and containment is in place
• Forensic investigation has identified all persistence mechanisms
• All compromised systems have been identified and scoped
• Ready to remove attacker artifacts and restore clean state
• Post-containment phase requires systematic cleanup

Common Misconfigurations & Verification

• The #1 reinfection cause is missed persistence: killing the running process and deleting the binary leaves the relaunch mechanism intact. Sweep every autostart class — Run/RunOnce keys, scheduled tasks (schtasks /query /v), services, WMI __EventFilter/CommandLineEventConsumer/FilterToConsumerBinding, DLL search-order/AppInit_DLLs hijacks, and Linux cron/systemd/rc.local/.bashrc/authorized_keys. Autoruns alone misses fileless WMI and COM hijacks — verify those explicitly.
• Eradicate fleet-wide, not host-by-host: the same implant usually lives on multiple hosts. A clean single endpoint reinfects within hours from a peer you didn't scope. Hunt the IOC/YARA signature across the whole estate before lifting isolation.
• Credential reset ordering matters: rotate compromised accounts and double-reset krbtgt (twice, 12+ hours apart for replication) — a single reset leaves Golden Tickets valid. Revoke cloud refresh tokens; a password change alone doesn't kill an active session.
• Patch the entry vector or it's theater: if you don't remediate the initial-access vuln (unpatched edge device, exposed RDP, phished cred without MFA) the attacker simply returns.
• Concrete verification the action worked: re-run Autorunsc and confirm zero unknown/unsigned entries; re-run YARA across the host and get zero hits; confirm no established C2 connections (Get-NetTCPConnection/netstat to non-internal IPs); verify EDR agent healthy and reporting. For rootkits/bootkits or any uncertainty, re-image from known-good media rather than trusting a clean scan.

Prerequisites

• Completed forensic analysis identifying all malware artifacts
• List of all compromised systems and accounts
• EDR/AV with updated signatures deployed
• YARA rules for the specific malware family
• Clean system images or verified backups for restoration
• Network isolation still in effect during eradication