{
  "family": "rpcdcom",
  "sample_count": 3,
  "category": "advanced_threat",
  "description": "Exploit:Win32/Rpcdcom is an extremely critical vulnerability detection that identifies attempts to exploit the notorious **MS03-026** vulnerability in the Microsoft RPC (Remote Procedure Call) DCOM interface. This specific exploit is infamous because it was the primary propagation vector for the devastating **Blaster** (and Nachi) worms in 2003, which caused billions of dollars in damage globally.<br><br><b>Understanding Rpcdcom (MS03-026)</b><br>To an end-user, a successful exploit often results in the system repeatedly and unexpectedly restarting with an error message about `NT AUTHORITY\\SYSTEM`. For a network administrator, an Rpcdcom alert indicates that an unpatched machine is under active attack, or worse, that a worm is actively scanning and propagating within the internal network (`T1210`). The vulnerability allows for unauthenticated Remote Code Execution (RCE) at the SYSTEM level.<br><br><b>Execution and Exploitation Mechanics</b><br>The attacker or worm sends a specially crafted, oversized packet to port 135 (the RPC Endpoint Mapper) on the target machine. This triggers a buffer overflow in the RPC DCOM interface (`T1190`), allowing the attacker to inject and execute arbitrary shellcode in the context of the `SYSTEM` account (`T1068`). Once the shellcode executes, it typically drops a secondary payload (like `msblast.exe`) and initiates a TFTP (`T1105`) transfer to pull down the rest of the worm's components, establishing persistence and beginning to scan for new targets.<br><br><b>Indicators of Compromise & Impact</b><br>The impact is total, unauthenticated system compromise. Network IoCs include a massive spike in traffic on TCP port 135 (RPC) and UDP port 69 (TFTP). Host-based IoCs include the unexpected termination of the `svchost.exe` process (which hosts the RPC service), resulting in the classic 60-second shutdown timer. The presence of files like `msblast.exe` or `teekids.exe` in the `System32` directory is a definitive indicator.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Rpcdcom and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Rpcdcom is classified as a Advanced Threat. Documented across security telemetry, it is engineered to execute unauthorized operations, establish persistent footholds on target endpoints, and facilitate malicious campaigns targeting enterprise and individual environments."
      }
    },
    {
      "@type": "Question",
      "name": "How does Rpcdcom establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Rpcdcom typically establishes persistence through registry run keys, scheduled tasks, or service installations, while evading signature-based antivirus solutions through code obfuscation, memory injection, or anti-analysis sandbox checks."
      }
    },
    {
      "@type": "Question",
      "name": "What are the essential incident response steps for mitigating a Rpcdcom compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Rpcdcom should immediately isolate affected endpoints from the network, perform memory triage to capture volatile forensic artifacts, audit registry and startup persistence mechanisms, revoke exposed user credentials, and restore systems from verified, clean backups."
      }
    },
    {
      "@type": "Question",
      "name": "What lateral movement and credential access tactics does Rpcdcom leverage in enterprise intrusions?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Rpcdcom frequently utilizes privileged account harvesting techniques such as LSASS memory dumping, Kerberoasting, and token impersonation to escalate privileges. Once administrative credentials are acquired, it pivots across the victim network utilizing living-off-the-land binaries (LOLBins) such as WMI, PowerShell remoting, and PsExec, or abuses remote desktop protocols (RDP) to reach critical internal repositories and domain controllers."
      }
    },
    {
      "@type": "Question",
      "name": "How does Rpcdcom maintain covert communications and evade perimeter network monitoring?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Rpcdcom often relies on multi-stage command and control (C2) architectures utilizing encrypted protocols over standard web ports (HTTPS/443 or DNS tunneling) to blend in with legitimate enterprise network traffic. Many variants incorporate proxy networks, domain fronting, or cloud services (such as Microsoft Graph API, Google Drive, or Telegram) to masquerade C2 channels, bypassing traditional signature-based egress filtering."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1210",
    "T1068",
    "T1190"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1190",
      "name": "Exploit Public-Facing Application (MS03-026 RPC DCOM)",
      "tactic": "Initial Access"
    },
    {
      "id": "T1210",
      "name": "Exploitation of Remote Services (Worm propagation)",
      "tactic": "Lateral Movement"
    },
    {
      "id": "T1068",
      "name": "Exploitation for Privilege Escalation (Executing as SYSTEM)",
      "tactic": "Privilege Escalation"
    }
  ],
  "containment_steps": [
    "Immediately disconnect the affected machine from the network; if it is infected with Blaster, it is actively attacking other systems.",
    "Apply the MS03-026 security patch (and all subsequent Windows updates) immediately.",
    "Block TCP port 135 and UDP port 69 (TFTP) at the network perimeter firewall to prevent external exploitation and inbound payload transfers.",
    "Run a dedicated removal tool for the Blaster worm to clear the registry persistence and remove the malicious executables."
  ],
  "what_to_avoid": [
    "Do not connect an unpatched legacy system (like Windows XP or 2000) directly to the internet without a hardware firewall blocking port 135.",
    "Avoid assuming the network is safe just because the worm was removed; you must apply the patch or it will be reinfected instantly."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "execution",
    "persistence"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}