The 'Decimal IP' campaign refers to a security threat involving the compromise of websites through the use of decimal notation IP addresses. In this campaign, attackers exploit the way some web browsers and systems interpret IP addresses written in decimal format rather than the standard dotted-decimal notation. By registering or injecting malicious content into websites accessed via decimal IP addresses, attackers can bypass certain security controls or evade detection mechanisms that rely on standard IP address formats. This technique is often used to deliver exploit kits, such as the Rig exploit kit, which can compromise visitor systems by exploiting browser or plugin vulnerabilities. The campaign is primarily identified through OSINT sources and involves compromised websites that serve malicious payloads when accessed through these decimal IP addresses. Although the severity is classified as low and no known exploits in the wild have been reported, the threat leverages a subtle method of obfuscation that can facilitate drive-by downloads or malware distribution. The lack of specific affected versions or patches suggests this is more a technique or campaign rather than a vulnerability in a particular product. The threat level and analysis scores indicate moderate concern but limited immediate impact.

For European organizations, the 'Decimal IP' campaign poses a risk mainly through compromised websites that may be visited by employees or users. If users access these sites via decimal IP addresses, they could be exposed to exploit kits that attempt to deliver malware, potentially leading to system compromise, data theft, or lateral movement within networks. Although the campaign is rated low severity, the stealthy nature of decimal IP obfuscation can hinder detection by traditional security tools, increasing the risk of successful infection. European organizations with employees who frequently browse external websites or those that rely on web-based applications without strict URL filtering may be more vulnerable. Additionally, sectors with high-value targets, such as finance, government, or critical infrastructure, could face increased risk if attackers leverage this technique to gain initial access. The absence of known exploits in the wild reduces immediate threat but does not eliminate the potential for future exploitation or targeted attacks using this method.

To mitigate risks from the 'Decimal IP' campaign, European organizations should implement advanced URL filtering and web traffic inspection that recognizes and normalizes IP addresses in all formats, including decimal notation. Security tools such as web proxies, firewalls, and intrusion detection systems should be configured to detect and block access to known malicious IP addresses regardless of notation. Regular updates and patching of browsers, plugins, and endpoint security solutions are critical to prevent exploitation via drive-by downloads. User awareness training should include information about the risks of accessing unknown or suspicious websites, especially those accessed via unusual IP address formats. Network monitoring should be enhanced to detect anomalous web traffic patterns and connections to suspicious IP addresses. Organizations should also leverage threat intelligence feeds to stay informed about compromised sites and emerging exploit kits like Rig. Finally, implementing application whitelisting and restricting execution of unauthorized code can reduce the impact of potential infections.