ISC Stormcast April 28, 2025: Key Cybersecurity Threats and Tools

The latest episode of the SANS Internet Storm Center (ISC) Stormcast, released on April 28, 2025, covers critical cybersecurity threats, including DKIM replay attacks, SSL.com vulnerabilities, and updates to XORSearch. This daily podcast, licensed under Creative Commons Attribution-Noncommercial 3.0 United States, provides actionable insights for security professionals¹. Below, we break down the key topics and their implications.

TL;DR: Key Takeaways

DKIM replay attacks and SSL.com vulnerabilities are actively exploited.
XORSearch updates improve malware detection capabilities.
Tools like SRUM-DUMP v3 and DShield-SIEM aid in forensic analysis and log monitoring.

Threat Analysis: DKIM Replay Attacks and SSL.com Vulnerabilities

The podcast highlights DKIM replay attacks, where attackers reuse valid DKIM signatures to bypass email authentication. This technique can facilitate phishing or business email compromise (BEC) campaigns. SSL.com vulnerabilities, though unspecified in detail, are noted as high-risk due to their potential impact on certificate validation¹. Organizations relying on SSL/TLS certificates should verify patches and monitor for anomalous traffic.

Tool Updates: XORSearch and SRUM-DUMP v3

XORSearch, a tool for identifying XOR-encoded malware strings, has been updated to handle newer obfuscation techniques. Meanwhile, SRUM-DUMP v3 by Mark Baggett analyzes Windows SRUM databases (srudb.dat) for forensic evidence. The tool’s GUI wizard and customizable XLSX output help flag suspicious activity, such as malware exfiltrating data over Wi-Fi².

DShield-SIEM Log Ingestion Issues

The ELK-based DShield-SIEM, used for honeypot log analysis, faced disruptions due to a Filebeat version mismatch (8.15.1 vs. 8.17.3). The ISC Diary recommends using Elastic Dev Tools API to resolve “missing replica shards” errors³. This underscores the importance of version compatibility in SIEM deployments.

Relevance and Remediation

For defenders, monitoring DKIM-signed emails for replay attempts and updating SSL.com certificates are priority actions. Red teams can leverage XORSearch updates to test detection evasion. The SRUM-DUMP tool is invaluable for post-exploitation forensics, while DShield-SIEM users should ensure Filebeat version alignment.

Conclusion

The April 28 ISC Stormcast episode underscores the dynamic nature of cybersecurity threats and tools. Staying informed about DKIM replay attacks, SSL.com vulnerabilities, and tool updates like XORSearch and SRUM-DUMP v3 is critical for maintaining robust defenses.