Certified: The Security+ Prepcast

In this episode, we are continuing our focus on network-based indicators of cyberattacks. Last time, we explored denial-of-service and domain name system threats. Now, we’ll dive into wireless attack indicators, on-path or man-in-the-middle attacks, and credential replay attempts. Each of these threats targets different layers of the network, and all can be spotted through careful monitoring and pattern recognition.
Let’s begin with wireless attacks. Wireless networks offer flexibility, but they also expose organizations to unique risks. One of the most common wireless threats is the rogue access point. A rogue access point is a wireless device that has been installed without proper authorization. It might be a legitimate device brought in by an employee for convenience, or it might be a tool planted by an attacker to lure users and steal data.
Indicators of rogue access points include duplicate network names, devices broadcasting stronger signals than the legitimate access points, or unfamiliar MAC addresses showing up in wireless logs. Users may also experience intermittent connectivity or strange redirections when connected to what they believe is the correct network.
Another wireless threat is the de-authentication flood. In this attack, the attacker sends a large number of de-authentication frames to wireless clients, forcing them to disconnect from the network. These disruptions can be used to push users toward a rogue access point or to cause a denial-of-service condition.
To detect these wireless attacks, organizations should deploy wireless intrusion detection systems that monitor for unauthorized devices, unusual channel usage, and abnormal connection behaviors. Logs from wireless controllers should be reviewed for de-authentication spikes, and alerts should be configured for unauthorized SSIDs or excessive roaming events.
Best practices for securing wireless networks include using Wi-Fi Protected Access version three for encryption, disabling unused wireless features, and requiring certificate-based authentication. Network segmentation should also be used to separate wireless traffic from sensitive internal systems, minimizing the risk of lateral movement after a wireless compromise.
Next, let’s examine on-path attacks—also known as man-in-the-middle attacks. In this threat scenario, an attacker intercepts communications between two parties without either one realizing. The attacker may passively eavesdrop or actively manipulate the data being exchanged.
Signs of on-path attacks include unusual certificate warnings during web browsing, unexpected session resets, or the presence of unfamiliar certificates in the trust store. Users may notice that their secure connections are slower, that their credentials are rejected without explanation, or that transactions fail without obvious cause.
One classic example involves attackers placing themselves between a user and a public Wi-Fi hotspot. As the user connects, the attacker silently intercepts and relays traffic while stealing credentials or injecting malicious code into web pages. In other cases, malware on a compromised router or endpoint allows attackers to alter DNS settings or redirect requests to fake websites.
To detect man-in-the-middle activity, administrators should monitor for abnormal traffic patterns, unexpected changes to routing tables, or mismatched certificate chains. Tools that verify endpoint certificate fingerprints and validate server authenticity can help identify unauthorized changes.
Prevention starts with strong encryption. All communication should use Transport Layer Security, and certificates should be signed by trusted authorities and validated at the client side. Certificate pinning and mutual authentication add further protection, ensuring that both parties verify each other before data is exchanged. Organizations should also use encrypted protocols like HTTPS, SFTP, and secure shell to protect sensitive communications from interception.
Finally, let’s look at credential replay attacks. In a replay attack, the attacker captures a valid login session or authentication token and resends it to gain unauthorized access. This is possible when authentication protocols lack replay protection, such as unique session identifiers or time-stamped requests.
Indicators of a credential replay attack include repeated login attempts from the same account in short succession, successful logins from unusual locations or times, or authentication events using identical session parameters across different attempts. You might also notice failed logins followed by successful ones using previously recorded values—especially in environments with older or custom-built authentication mechanisms.
Credential replay attacks are particularly effective against systems that use static passwords or reusable tokens without any session validation. Attackers may use packet sniffers to capture login credentials on unencrypted networks or steal cookies and session tokens through other forms of malware.
To prevent replay attacks, organizations should implement multi-factor authentication and use secure authentication protocols that support nonce values, time-sensitive tokens, or cryptographic challenge-response mechanisms. Single sign-on tools that use signed and encrypted assertions can also reduce the risk.
Session expiration and token rotation help limit the window of opportunity for replay attacks. Logs should be monitored for session anomalies, such as concurrent logins from distant locations or repeated access attempts using the same credentials across multiple endpoints.
As you prepare for the Security Plus exam, remember that each of these threats—rogue wireless access, on-path interception, and credential replay—can be detected if you know the signs and understand the attack methods. You may be given a scenario with log excerpts or system behaviors, and your task will be to recognize the likely cause and suggest a defense. Focus on wireless integrity, secure protocol use, and strong authentication mechanisms as the key principles for this section.