The BEST practice for ensuring the integrity of the recovered system after an intrusion is to restore the OS, patches, and application from a backup. This will ensure that the system is in a known good state, without any potential residual malicious code or changes from the intrusion. Restoring from a backup also enables the organization to revert to a previous configuration that has been tested and known to be secure. This step should be taken prior to conducting a thorough investigation and forensic analysis to determine the cause and extent of the intrusion.

Initiating incident response is the first course of action for an information security manager when an employee reports the loss of a personal mobile device containing corporate information. This will help to contain the incident, assess the impact, and take appropriate measures to prevent or mitigate further damage. According to ISACA, incident management is one of the key processes for information security governance. Initiating a device reset, disabling remote access, and conducting a risk assessment are possible subsequent actions, but they should be part of the incident response plan. Reference: 1: Find, lock, or erase a lost Android device - Google Account Help 2: Find, lock, or erase a lost Android device - Android Help 3: Lost or Stolen Mobile Device Procedure - Information Security Office : CISM Practice Quiz | CISM Exam Prep | ISACA : 200 CISM Exam Prep Questions | Free Practice Test | Simplilearn : CISM practice questions to prep for the exam | TechTarget

The primary objective of performing a post-incident review is to identify the root cause of the incident. After an incident has occurred, the post-incident review process involves gathering and analyzing evidence to determine the cause of the incident. This analysis will help to identify both the underlying vulnerability that allowed the incident to occur, as well as any control improvements that should be implemented to prevent similar incidents from occurring in the future. Additionally, the post-incident review process can also be used to re-evaluate the impact of the incident, as well as any potential implications for the organization.