During a security review of a modern document processing web service, an analyst examines … — CompTIA Security+

During a security review of a modern document processing web service, an analyst examines crash logs and source code after an unexpected service degradation. The backend endpoint accepts a JSON request containing a document rendering configuration. The service fetches remote custom template assets via HTTP based on a user-provided URL and parses binary header blocks into a fixed-size internal C-style buffer without checking the size of the incoming string. Log analysis reveals that an attacker submitted a payload pointing to $http://169.254.169.254/latest/meta-data/$ alongside a $4,096$ -byte header string into a $512$ -byte memory buffer, causing an application crash and sensitive cloud infrastructure credential exposure. Which of the following mitigation controls should the security team implement to remediate these specific software vulnerabilities? (Select TWO)

Enforce strict outbound URL target validation using a strict domain allowlist and block requests destination targets resolving to internal or link-local IP addresses.Answer
Refactor the memory handling logic to use length-bounded string operations and perform strict input size validation prior to buffer copying.Answer
C
Implement parameterized database queries with pre-compiled SQL statements across the document rendering endpoint routines.
D
Deploy network layer router access control lists (ACLs) to block all incoming ICMP and UDP management traffic targeting the server host.

Answer

To address the vulnerabilities identified in the scenario, the team must implement URL destination validation (blocking internal metadata IP ranges like

169.254.169.254

) to mitigate Server-Side Request Forgery (SSRF), and refactor memory operations to use bounds-checked functions that validate payload length against buffer size limits to prevent buffer overflows.

The scenario highlights two distinct software vulnerabilities: Server-Side Request Forgery (SSRF), evidenced by the attempt to retrieve internal cloud metadata (

169.254.169.254

), and a buffer overflow, evidenced by writing a

4,096

-byte string into a

512

-byte buffer. Restricting outbound HTTP targets using domain allowlists and blocking internal IP ranges directly mitigates SSRF. Refactoring code to validate input length and enforce bounds checks on memory allocations eliminates buffer overflow vulnerabilities.

Step-by-Step Solution

Analyze the incident details to identify the primary application vulnerabilities.

The request fetching

http://169.254.169.254/latest/meta-data/

indicates Server-Side Request Forgery (SSRF), while copying a

4,096

-byte header into a

512

-byte buffer indicates a buffer overflow.

Correctly categorizing the application flaws ensures appropriate mitigations are chosen.

Evaluate remediation controls for Server-Side Request Forgery (SSRF).

Restricting remote request destinations using allowlists and blocking access to internal or link-local IP addresses (such as cloud metadata endpoints) neutralizes SSRF risks.

SSRF occurs when the application accepts arbitrary external URLs and executes requests on behalf of the server to internal resources.

Evaluate remediation controls for the buffer overflow flaw.

Implementing bounds checking and using length-bounded memory operations prevents excessive input from overwriting adjacent memory spaces.

Buffer overflows stem from inadequate length checks on incoming binary or text data before writing to allocated memory.

Key Concept

Mitigating Application Vulnerabilities (SSRF and Buffer Overflow)

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

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