Nexcorium Mirai Variant Actively Exploiting IoT DVR and Router Vulnerabilities at Scale
Fortinet's FortiGuard Labs is tracking Nexcorium, a Mirai botnet variant conducting active exploitation against TBK DVR-4104/4216 devices via CVE-2024-3721 (EPSS 0.839) and Huawei HG532 routers via CVE-2017-17215 (EPSS 0.927, public exploit at EDB-43414). Both CVEs carry high EPSS scores reflecting genuine ongoing exploitation at scale rather than theoretical risk. The campaign follows the standard Mirai playbook — exploit unpatched consumer and SMB-grade IoT gear, grow C2-connected botnet capacity, and leverage for DDoS or secondary payload staging. No KEV listing for either CVE, though the exploitation signals are unambiguous.
CVE-2017-17215 being weaponized in 2026 — nine years post-disclosure — is the clearest possible illustration of the IoT patch debt problem. The EPSS 0.927 reflects sustained real-world exploitation, not decay. Ranking's 'critical' severity overstates direct financial institution relevance given the narrow exposure path (TBK DVRs, Huawei CPE); the actual threat surface is the botnet's DDoS capacity against edge infrastructure, not direct compromise of enterprise assets. Downgraded to notable accordingly.
Second Mirai-family disclosure in the same day (after this morning's Unit 42 TP-Link write-up on story 5374) — the pattern is consistent: unpatchable consumer/SMB gear powering DDoS-capable capacity against edge infrastructure and hosting providers. CVE-2017-17215 live in 2026 is the nine-year tail of the Huawei HG532 problem that drove the original Mirai successors. Treat as vendor-risk and supplier-network exposure, not direct enterprise compromise.