15 Malware Analysis Interview Questions and Answers

Malware analysis is a critical skill in the field of cybersecurity, involving the study of malicious software to understand its behavior, origin, and impact. This process is essential for developing effective defense mechanisms and mitigating potential threats. With the increasing sophistication of cyber-attacks, expertise in malware analysis has become highly sought after by employers across various industries.

This article provides a curated selection of interview questions designed to test and enhance your knowledge in malware analysis. By working through these questions and their detailed answers, you will be better prepared to demonstrate your proficiency and problem-solving abilities in this specialized area during your interviews.

Malware Analysis Interview Questions and Answers

1. What are the key differences between static and dynamic analysis?

Static analysis examines a program’s code without executing it, using techniques like disassembly and decompilation to identify malicious patterns and understand the program’s structure. It is faster and safer as it doesn’t trigger malicious behavior. Dynamic analysis, however, involves executing the program in a controlled environment to observe real-time behavior, such as network activity and system changes, providing insights into the malware’s impact.

2. How would you monitor and log the behavior of a suspicious executable?

To monitor a suspicious executable, use dynamic analysis and sandboxing. Tools like Cuckoo Sandbox, Process Monitor, and Wireshark help observe behavior, track system changes, and analyze network traffic.

3. How do you analyze network traffic to identify malicious activity?

Analyzing network traffic for malicious activity involves capturing and inspecting data packets with tools like Wireshark or tcpdump. Techniques include traffic analysis to identify unusual patterns, anomaly detection using machine learning, signature-based detection with IDS like Snort, and behavioral analysis to monitor deviations from normal behavior.

4. Write a YARA rule to detect a specific type of malware based on given characteristics.

YARA is used to identify malware by matching patterns in files. A YARA rule consists of meta, strings, and condition sections. Here’s an example:

rule ExampleMalware
{
    meta:
        description = "Detects Example Malware"
        author = "Analyst"
        date = "2023-10-01"
    
    strings:
        $a = { 6A 40 68 00 30 00 00 6A 14 8D 91 }
        $b = "malicious_string"
        $c = /malicious_regex/
    
    condition:
        $a or $b or $c
}

5. How would you implement API hooking to intercept function calls made by malware?

API hooking intercepts function calls to monitor or modify behavior, useful for tracking malware actions. Methods include IAT Hooking, Inline Hooking, and using libraries like Microsoft Detours. Here’s an example of inline hooking in Windows:

#include <windows.h>

typedef int (WINAPI *MessageBoxW_t)(HWND, LPCWSTR, LPCWSTR, UINT);
MessageBoxW_t originalMessageBoxW = NULL;

int WINAPI HookedMessageBoxW(HWND hWnd, LPCWSTR lpText, LPCWSTR lpCaption, UINT uType) {
    return originalMessageBoxW(hWnd, L"Hooked!", lpCaption, uType);
}

void HookAPI() {
    HMODULE hUser32 = GetModuleHandle(L"user32.dll");
    if (hUser32) {
        originalMessageBoxW = (MessageBoxW_t)GetProcAddress(hUser32, "MessageBoxW");
        DWORD oldProtect;
        VirtualProtect(originalMessageBoxW, 5, PAGE_EXECUTE_READWRITE, &oldProtect);
        *(BYTE*)originalMessageBoxW = 0xE9;
        *(DWORD*)((BYTE*)originalMessageBoxW + 1) = (DWORD)HookedMessageBoxW - (DWORD)originalMessageBoxW - 5;
        VirtualProtect(originalMessageBoxW, 5, oldProtect, &oldProtect);
    }
}

6. What methods can be used to detect and remove rootkits from a system?

Rootkits are stealthy malware designed to gain unauthorized access while hiding their presence. Detection methods include signature-based detection, behavioral analysis, integrity checking, memory dump analysis, rootkit scanners, boot-time scanning, and manual inspection.

7. Identify common persistence mechanisms used by malware to survive reboots.

Common persistence mechanisms for malware include modifying registry keys, creating scheduled tasks, placing files in startup folders, installing services, bootkits, DLL hijacking, WMI event subscriptions, and browser extensions.

8. What are the differences between polymorphic and metamorphic malware, and how can they be detected?

Polymorphic malware changes its code slightly with each infection, while metamorphic malware completely rewrites its code. Detection methods for polymorphic malware include signature-based detection and heuristic analysis. Metamorphic malware is detected through behavioral analysis and advanced code analysis techniques.

9. Outline the steps you would take during an incident response to a malware infection.

Incident response to malware involves identification, containment, eradication, recovery, post-incident analysis, and documentation. These steps help manage and mitigate the impact of malware infections.

10. Describe your approach to conducting advanced threat hunting operations in an enterprise environment.

Advanced threat hunting involves data collection, threat intelligence integration, behavioral analysis, hypothesis-driven investigation, advanced analytics, incident response, and continuous improvement. This proactive approach helps identify and mitigate potential security threats.

11. Explain the process of performing behavioral analysis on a malware sample.

Behavioral analysis of malware involves setting up a controlled environment, executing the malware, observing system changes, capturing network traffic, analyzing persistence mechanisms, and documenting findings.

12. How do you identify and utilize Indicators of Compromise (IoCs) in malware analysis?

Indicators of Compromise (IoCs) are artifacts indicating potential intrusion. They are identified through static and dynamic analysis and used for detection, response, threat intelligence sharing, and forensic analysis.

13. Discuss the classification of different types of malware and their characteristics.

Malware types include viruses, worms, trojans, ransomware, spyware, adware, rootkits, keyloggers, and botnets. Each type has distinct characteristics and methods of operation.

14. How do you integrate threat intelligence into your malware analysis workflow?

Integrating threat intelligence into malware analysis involves collecting intelligence, enriching malware samples, automated analysis and correlation, contextual analysis, and reporting and sharing. This enhances understanding and mitigation of threats.

15. What automated analysis tools do you use, and how do they assist in malware analysis?

Automated analysis tools like Cuckoo Sandbox, IDA Pro, Ghidra, Wireshark, Zeek, YARA, and VirusTotal assist in identifying and understanding malicious behavior efficiently.