NIST Special Publication 800-171 Revision 2

Discussion:

Periodic scans of organizational systems and real-time scans of files from external sources can detect malicious code. Malicious code can be encoded in various formats (e.g., UUENCODE, Unicode), contained within compressed or hidden files, or hidden in files using techniques such as steganography. Malicious code can be inserted into systems in a variety of ways including web accesses, electronic mail, electronic mail attachments, and portable storage devices. Malicious code insertions occur through the exploitation of system vulnerabilities.

Upon assessment, assessors must determine if-

3.14.5[a] the frequency for malicious code scans is defined.
3.14.5[b] malicious code scans are performed with the defined frequency.
3.14.5[c] real-time malicious code scans of files from external sources as files are downloaded, opened, or executed are performed.

Assessors are instructed to-

Examine: [SELECT FROM: System and information integrity policy; configuration management policy and procedures; procedures addressing malicious code protection; malicious code protection mechanisms; records of malicious code protection updates; system security plan; system design documentation; system configuration settings and associated documentation; scan results from malicious code protection mechanisms; record of actions initiated by malicious code protection mechanisms in response to malicious code detection; system audit logs and records; other relevant documents or records].

Interview: [SELECT FROM: System or network administrators; personnel with information security responsibilities; personnel installing, configuring, and maintaining the system; personnel with responsibility for malicious code protection; personnel with configuration management responsibility].

Test: [SELECT FROM: Organizational processes for employing, updating, and configuring malicious code protection mechanisms; organizational process for addressing false positives and resulting potential impact; mechanisms supporting or implementing malicious code protection mechanisms (including updates and configurations); mechanisms supporting or implementing malicious code scanning and subsequent actions].