Google Cloud Certified Security-Operations-Engineer Google Study Notes

Comprehensive and Detailed 150 to 250 words of Explanation From Exact Extract Google Security Operations Engineer documents:

To achieve improved coverage and reduced false positives "as quickly as possible," the correct action is to enable curated detections. These are pre-built rules managed entirely by Google, removing the need for internal development time.2

According to Google Security Operations documentation, Curated Detections are "built by our Google Cloud Threat Intelligence (GCTI) team, and are actively maintained to reduce manual toil in your team."3 The documentation explicitly highlights their speed and fidelity: "Our detections provide security teams with high quality, actionable, out-of-the-box threat detection content...4 This release helps understaffed and overstressed security teams... quickly identify threats."5

Furthermore, Curated Detections are categorized into "Precise" and "Broad" types to directly address false positive concerns.6 The documentation states: "Precise rules: Find malicious behavior with a higher degree of confidence with fewer false positives due to the more specific nature of the rule."7 By enabling these, an organization immediately gains high-fidelity coverage without the lead time required to "Develop" or "Design" custom YARA-L rules (Options C and D) or the potential noise of raw TIP data (Option B).8

The primary investigation tool for exploring relationships and historical activity in Google Security Operations is the UDM (Universal Data Model) search. The platform's curated views, such as the "User View," are built on top of this search capability.

To find all assets a user has interacted with, an analyst would perform a UDM search for the specific user (e.g., principal.user.userid = "suspicious_user") over the specified time range. The search results will include all UDM events associated with that user. Within these events, the analyst can examine all populated asset fields, such as principal.asset.hostname, principal.ip, target.resource.name, and target.user.userid (for interactions with service accounts).

This UDM search allows the analyst to pivot from the user entity to all related asset entities, directly answering the question of "what assets the user has interacted with." While the wording of Option A is slightly backward (it's more efficient to query for the user and find the hostnames), it is the only option that correctly identifies the UDM search as the tool used to find user-to-asset (hostname) relationships. Options B (Retrohunt), C (Raw Log Scan), and D (Ingestion Report) are incorrect tools for this investigative task.

(Reference: Google Cloud documentation, "Google SecOps UM Search overview"; "Investigate a user"; "Universal Data Model noun list")

Comprehensive and Detailed Explanation

The correct solution is Option D. The goal is to exclude events (i.e., stop false positives) when the principal.ip field contains any IP from the trusted 192.168.2.0/24 subnet.

The principal.ip field in UDM is a repeated field, meaning it can hold an array of values (e.g., ["1.2.3.4", "192.168.2.5"]). YARA-L provides the any and all quantifiers to handle repeated fields.9

any $e.principal.ip: This checks if at least one IP in the array meets the condition.

all $e.principal.ip: This checks if every IP in the array meets the condition.

The function net.ip_in_range_cidr(...) returns true if an IP is in the specified range.

Therefore, the logic we need is: "do not trigger this rule if any of the IPs in the principal.ip field are in the 192.168.2.0/24 range."

This translates directly to the YARA-L syntax: not net.ip_in_range_cidr(any $e.principal.ip, "192.168.2.0/24")

Option B would only find events from that subnet.

Option A would only find events where all associated IPs are in that subnet.

Option C is the logical inverse of A and would incorrectly filter out events that might be malicious (e.g., ["1.2.3.4", "192.168.2.5"] would not be excluded because all IPs are not in the range).

Exact Extract from Google Security Operations Documents:

YARA-L 2.0 language syntax > Repeated fields and boolean expressions: When a boolean expression, such as a function call, is applied to a repeated field, you can use the any or all keywords to specify how the expression should be evaluated.10

any : The expression evaluates to true if it is true for at least one of the values in the repeated field.

all : The expression evaluates to true only if it is true for all of the values in the repeated field.

Functions > net.ip_in_range_cidr: The net.ip_in_range_cidr function is useful to bind rules to specific parts of the network.11 To exclude all private netblocks as defined in RFC1918, you can add a not to the start of the criteria:

and not (net.ip_in_range_cidr(any $e.principal.ip, "10.0.0.0/8") or net.ip_in_range_cidr(any $e.principal.ip, "172.16.0.0/12") or net.ip_in_range_cidr(any $e.principal.ip, "192.168.0.0/16"))

The correct, low-impact solution for augmenting a Google-managed parser is to use a parser extension. The problem states that the base parser is still working, but needs to be supplemented to map two new fields.

Copying the entire parser (Option A) is a high-impact, high-maintenance solution ("Customer Specific Parser"). This action makes the organization responsible for all future updates and breaks the link to Google's managed updates, which is not a minimal-impact solution.

The intended, modern solution is the parser extension. This feature allows an engineer to write a small, targeted snippet of Code-Based Normalization (CBN) code that executes after the Google-managed base parser. This extension code can access the raw_log and perform the specific logic needed to extract the two unmapped fields and assign them to their proper Universal Data Model (UDM) fields.

This approach is the fastest to deploy and minimizes change management impact because the core parser remains managed and updated by Google, while the extension simply adds the custom logic on top. Option B, "Extract Additional Fields," is a UI-driven feature, but the underlying mechanism that saves and deploys this logic is the parser extension. Option D is the more precise description of the technical solution.

(Reference: Google Cloud documentation, "Manage parsers"; "Parser extensions"; "Code-Based Normalization (CBN) syntax")