Network-based Yara
To write a network-based Yara rule, you need to specify the network traffic characteristics of the malware that you are trying to detect. Here is an example of a simple network-based Yara rule:
rule example_network_rule { condition: network.ip == "192.168.1.1" and network.port == 80 }
This Yara rule will match any network traffic that originates from the IP address “192.168.1.1” and is sent to port 80. You can use a variety of network traffic characteristics in your Yara rules, including IP addresses, port numbers, protocols, and packet payloads. You can also use logical operators and other syntax elements to create more complex and specific rules. For example, the following rule uses a regular expression to match the packet payload and a logical operator to specify that the traffic must be sent over either the HTTP or HTTPS protocols:
rule example_complex_network_rule { condition: network.protocol in { "HTTP", "HTTPS" } and (network.payload matches /login/ or network.payload matches /password/) }
It is essential to carefully consider which network traffic characteristics are most relevant for detecting the specific type of malware that you are targeting. You can use multiple characteristics in a single Yara rule to create more specific and sophisticated detection methods.
Threat Hunting Using Yara
Threat hunting is a proactive approach to identifying and mitigating cyber threats that have already entered an organization’s network. It involves actively searching for indicators of compromise (IOC) and signs of malicious activity that may not have been detected by traditional security measures such as antivirus software or firewalls. Threat hunters use a variety of techniques to detect and analyze potential threats, including analyzing log files, network traffic, and system configurations. They may also use tools such as threat intelligence feeds, security incident and event management (SIEM) systems, and malware analysis tools to help identify potential threats. The goal of threat hunting is to detect and mitigate threats as early as possible in the attack life cycle before they can do significant damage. It is an important part of an organization’s overall cybersecurity strategy and can help reduce the risk of successful attacks and data breaches.