What is Deserialization in Phishing?

In the realm of phishing, deserialization refers to the cybercriminal technique of exploiting vulnerabilities in the process of converting serialized data back into its original object format to execute arbitrary code or deliver payloads.

Definition

Deserialization in phishing involves exploiting deserialization processes within an application to inject malicious code or manipulate data structures for executing phishing or broader attack goals.

In phishing attacks, deserialization is a method where threat actors take advantage of how applications convert data strings into usable objects. When these processes are flawed or insecure, attackers can introduce untrusted inputs that disrupt expected flows, often leading to remote code execution or database manipulation.

Why It Matters

Deserialization vulnerabilities are critical to phishing because they can be exploited remotely, allowing attackers to craft specific payloads that alter the behavior of an application. Threat actors often shape these vulnerabilities into an attack vector that lets them bypass application controls and escalate privileges, inserting malfeasance into otherwise secure processes.

This method’s efficacy in phishing campaigns comes from its ability to deliver intricate attacks through seemingly benign data streams. Attackers may lure targets into inadvertently triggering these vulnerabilities with crafted emails or attachments that leverage systemic flaws, often bypassing perimeter defenses because they operate beyond the initial network entry point.

In Practice

Imagine an attacker sends a phishing email that includes a link purportedly leading to a harmless document storage service. The email is crafted for a particular company, using internal jargon and official-looking formatting to enhance credibility. When the target clicks the link, under the surface, a deserialization exploit is activated that leverages a vulnerability in the service’s backend:


POST /upload HTTP/1.1

Host: storage.example-comp.com

Content-Type: application/x-java-serialized-object

...

payload-data-injected-blob

...

Here, the attacker has embedded a serialized payload within the data transfer that the service automatically deserializes, leading to exploit execution on the server. This technique illustrates not only the method for initial access but also establishes persistence through escalated privileges.

Another example involves an engagement using a capture portal deceivingly presented as part of an IT maintenance routine. Consider a scenario where staff receive an urgent IT notice:


Subject: Critical System Update Needed

From: noreply@itsupport.example-comp.com



Dear User,



To continue using our services securely, please verify your account by clicking the link below. 



<a href="http://secure-update.example-comp.com/verify">



Thank you,

IT Support

The link points to a phishing site that uses deserialization vulnerabilities in an associated backend service to execute a payload, capturing user credentials on input but also running scripts that siphon session tokens once deserialization processes complete when users verify details.

Deserialization can even extend to mobile-focused phishing tactics. A well-timed SMS delivers links to applications or update requests that engage deserialization flaws specific to mobile device management applications, covertly executing payloads through deserialization endpoints often ignored by traditional perimeter defenses.

Related Terms

Understanding deserialization deeply ties into concepts like RCE (Remote Code Execution) where the execution occurs once deserialization occurs. It also relates closely to serialization itself, the process preceding deserialization. Finally, social engineering facilitates this process by increasing the likelihood of successful exploitation through manipulated context or user interaction.