350-201 · Question #29
A SOC analyst is investigating a recent email delivered to a high-value user for a customer whose network their organization monitors. The email includes a suspicious attachment titled "Invoice RE…
The correct answer is D. Obtain a copy of the file for detonation in a sandbox. When a file hash returns no results in open source threat intelligence, sandbox detonation is the appropriate next step to dynamically observe behavior and generate fresh indicators of compromise.
Question
A SOC analyst is investigating a recent email delivered to a high-value user for a customer whose network their organization monitors. The email includes a suspicious attachment titled "Invoice RE: 0004489". The hash of the file is gathered from the Cisco Email Security Appliance. After searching Open Source Intelligence, no available history of this hash is found anywhere on the web. What is the next step in analyzing this attachment to allow the analyst to gather indicators of compromise?
Options
- ARun and analyze the DLP Incident Summary Report from the Email Security Appliance
- BAsk the company to execute the payload for real time analysis
- CInvestigate further in open source repositories using YARA to find matches
- DObtain a copy of the file for detonation in a sandbox
How the community answered
(36 responses)- A6% (2)
- B14% (5)
- C3% (1)
- D78% (28)
Why each option
When a file hash returns no results in open source threat intelligence, sandbox detonation is the appropriate next step to dynamically observe behavior and generate fresh indicators of compromise.
The DLP Incident Summary Report tracks data loss prevention policy violations and would not reveal behavioral indicators of compromise for an unknown malware sample.
Asking the company to execute the payload on a live system risks actual infection and production damage, which is never an acceptable malware analysis method.
YARA rule matching requires known patterns or signatures to search against; since no OSINT results exist for this hash, there are no existing signatures to build a meaningful YARA match from at this stage.
Sandbox detonation executes the suspicious file in an isolated, monitored environment where behavioral indicators such as network connections, file system modifications, registry changes, and spawned processes can be captured without risk to production systems. This dynamic analysis approach is the correct escalation path when static hash lookups yield no results, enabling the analyst to produce original IOCs from a previously unknown sample.
Concept tested: Sandbox detonation for unknown malware IOC gathering
Source: https://www.cisco.com/c/en/us/products/security/threat-grid/index.html
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