Secure Error Handling & Logging Flashcards

Which information disclosed in a verbose stack trace is most useful to an attacker?

Answer: Framework/library versions, internal file paths, and query structure

Versions, paths, and query details help attackers find known vulnerabilities and craft targeted exploits.

What are appropriate file permissions for application log files?

Answer: Append/write for the application account and read access restricted to authorized administrators

Least privilege on logs prevents unauthorized reading or modification of sensitive audit data.

Under PCI DSS, how long must audit log history be retained?

Answer: At least one year, with the most recent three months immediately available

PCI DSS requires one year of audit trail history with at least three months readily available for analysis.

When logging a payment event, how should the primary account number (PAN) be handled?

Answer: Mask it so that only the last four digits are visible

Masking/truncation prevents exposure of cardholder data; Base64 is encoding, not protection.

Review: boolean isAdmin = true; try { isAdmin = checkRole(user); } catch (Exception e) { log.error(e); } — what is the flaw?

Answer: It fails open: if checkRole throws, the user is treated as an admin

Initializing to true means an exception leaves privileged access granted; it should default to false.

An attacker sends thousands of malformed requests to fill the disk with error logs. Which control best mitigates this?

Answer: Log rotation with size limits, rate limiting of repeated events, and disk-usage alerting

Rotation, throttling, and monitoring prevent log flooding from causing denial of service or hiding attacks.

Security logs are reviewed in a browser-based admin console. Which vulnerability must be addressed when displaying log entries?

Answer: Stored XSS via attacker-controlled data written to logs

Logged user input rendered unencoded in a web viewer can execute script in an administrator's browser.