Juliea, the SOC analyst, noticed large TXT and NULL payloads in the logs. This is indicative of a DNS exfiltration attempt. DNS exfiltration is a type of cyber attack where an attacker uses the DNS protocol to sneak data out of a network undetected. It typically involves the use of large TXT records, which can be used to carry data out of the network. NULL payloads can be used in this context to pad the DNS queries and make them less suspicious or to bypass security controls that inspect the content of DNS queries.

The steps involved in DNS exfiltration include:

The attacker compromises a system within the target network.

Malware on the compromised system encodes the data it wants to exfiltrate.

The encoded data is split into chunks that fit into DNS query sizes.

These chunks are sent as data in DNS queries or responses, often using TXT records.

An external attacker-controlled server receives the DNS queries and decodes the data.

References:

EC-Council’s Certified SOC Analyst (CSA) course material and study guides provide detailed information on various types of cyber attacks, including DNS exfiltration.

Online resources and practice questions for the Certified SOC Analyst (CSA) exam also cover this topic and can be used to verify the answer123.

Additional information on DNS exfiltration techniques and detection methods can be found in security blogs and articles that discuss the subject in depth456.