{
  "family": "blaster",
  "sample_count": 30,
  "category": "worm",
  "description": "Blaster (also widely cataloged as MSBlast, Lovsan, and Poosan) is one of the most famous and destructive self-propagating computer worms in internet history, first detected on August 11, 2003. Propagating at machine speed across the global IPv4 address space without requiring any email opening, attachment execution, or user interaction, Blaster scanned random IP subnets on TCP port 135 to find unpatched endpoints running Microsoft Windows 2000 and Windows XP. When an open port was found, Blaster exploited a critical stack buffer overflow in the Distributed Component Object Model (DCOM) interface of the Windows RPCSS service (CVE-2003-0352 / MS03-026). Once code execution was achieved, Blaster spawned an unauthenticated remote command shell on TCP port 4444 and instructed the compromised endpoint to download the full worm binary ('msblast.exe') from the attacking host via Trivial File Transfer Protocol (TFTP) over UDP port 69. The worm payload contained hidden text strings taunting Microsoft's founder ('billy gates why do you make this possible ? Stop making money and fix your software!!'). Additionally, Blaster was programmed to launch a coordinated distributed denial-of-service (DDoS) SYN flood against port 80 of windowsupdate.com starting on August 15, 2003, forcing Microsoft to temporarily take the Windows Update portal offline to protect global internet routing infrastructure. Blaster infected hundreds of thousands of computers worldwide within days, severely degrading internet traffic and accelerating the creation of modern Windows security baselines.",
  "cta": "Published by the SystemHelpdesk threat intelligence team.",
  "aliases": [
    "MSBlast",
    "Lovsan",
    "Poosan",
    "W32.Blaster.Worm",
    "Win32/Blaster"
  ],
  "enrichment_level": "curated_sourced",
  "faq": [
    {
      "@type": "Question",
      "name": "What was the Blaster (MSBlast) worm and how did it spread?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Blaster was an autonomous network worm that exploded in August 2003 by exploiting a DCOM RPC buffer overflow (CVE-2003-0352 / MS03-026) on TCP port 135 across Windows 2000 and XP systems."
      }
    },
    {
      "@type": "Question",
      "name": "What payload did Blaster drop on infected systems?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Blaster opened a remote shell on TCP port 4444 and downloaded msblast.exe into the Windows System32 directory using TFTP on UDP port 69."
      }
    },
    {
      "@type": "Question",
      "name": "What was Blaster's planned DDoS attack?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It contained code to launch a coordinated SYN flood against windowsupdate.com starting August 15, 2003, forcing Microsoft to redirect update traffic to prevent internet outages."
      }
    },
    {
      "@type": "Question",
      "name": "What message was hidden in the Blaster binary?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "It contained the strings 'I just want to say LOVE YOU SAN!!' and 'billy gates why do you make this possible ? Stop making money and fix your software!!'."
      }
    },
    {
      "@type": "Question",
      "name": "How was Blaster removed and prevented?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "By applying Microsoft Security Bulletin MS03-026, blocking inbound TCP port 135 and UDP port 69 at perimeter firewalls, and deleting the msblast.exe binary from System32."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1210",
    "T1059",
    "T1547.001",
    "T1498"
  ],
  "cisa_advisory": null,
  "exploited_cves": [
    "CVE-2003-0352"
  ],
  "iocs": {
    "file_hashes": [
      "2b6a5db21d00f7e44a42e5d7db69b466ea2084c55bc66c5d1e2e1329c31b312b",
      "a17387f5df2307ef086915091219b671a172776c59b67195721118182969b761"
    ],
    "delivery": [
      "Autonomous network worm propagation exploiting DCOM RPC buffer overflow CVE-2003-0352 over TCP port 135",
      "Automated TFTP download on UDP port 69 spawning command shell on TCP port 4444"
    ],
    "persistence": [
      "HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\Run entry pointing to msblast.exe in %SYSTEM32%",
      "Spawning of autonomous background scanning threads on system boot"
    ]
  },
  "lineage": {
    "derived_from": [],
    "variants": [
      "blaster_a",
      "blaster_b",
      "welchia_nachi_counterworm"
    ]
  },
  "ecosystem": [
    "windows",
    "windows_pe"
  ],
  "attack_stage": [
    "initial_access",
    "execution",
    "persistence",
    "lateral_movement",
    "impact"
  ],
  "last_updated": "2026-10-16",
  "sources": [
    {
      "name": "Microsoft Security Bulletin MS03-026: Buffer Overrun In RPC Interface Could Allow Code Execution",
      "url": "https://learn.microsoft.com/en-us/security-updates/securitybulletins/2003/ms03-026"
    },
    {
      "name": "CISA Alert TA03-223A: Blaster Worm",
      "url": "https://www.cisa.gov/uscert/cas/techalerts/TA03-223A.html"
    },
    {
      "name": "CERT Coordination Center Advisory CA-2003-20: W32/Blaster worm",
      "url": "https://www.cert.org/historical/advisories/CA-2003-20.html"
    }
  ],
  "target_platforms": [
    "Windows 10",
    "Windows 7",
    "Windows XP",
    "Windows Server"
  ]
}