{
  "family": "jeefo",
  "sample_count": 213,
  "category": "file_infector",
  "description": "Virus:Win32/Jeefo is a classic, highly destructive executable file infector (virus) that aggressively self-replicates by injecting its malicious code into every legitimate Windows executable (<code>.exe</code>) it can access, severely destabilizing the operating system.<br><br><b>Understanding Jeefo</b><br>To the end-user, a Jeefo infection causes widespread software corruption, application crashes, and extreme system slowdowns. For incident responders, Jeefo is a nightmare scenario of lateral movement and file destruction. Unlike modern trojans that hide, Jeefo is a true virus; its primary goal is aggressive propagation, appending its encrypted viral body to the end of legitimate files and modifying the entry point to execute the virus before the original application.<br><br><b>Execution and Evasion Strategies</b><br>Jeefo primarily spreads by users executing an already infected file, often downloaded from untrusted sources or shared via network drives. Upon execution, the virus becomes memory-resident. It immediately drops a hidden executable (often named <code>svchost.exe</code>) into the Windows directory and establishes persistence via the Registry Run keys (<code>HKLM\\Software\\Microsoft\\Windows\\CurrentVersion\\RunServices</code>). It then aggressively scans all local drives and mapped network shares, targeting and infecting every <code>.exe</code> file it finds. Jeefo employs polymorphic techniques to slightly alter its signature with every infection, hindering simple hash-based detection.<br><br><b>Indicators of Compromise & Impact</b><br>The impact is widespread file corruption and massive operational disruption. EDR platforms frequently trigger a flood of alerts for 'Suspicious File Modification' or 'Executable Entry Point Altered' as Jeefo rapidly rewrites thousands of files. Incident responders will notice legitimate applications suddenly increasing in size (typically by exactly 36,288 bytes, the size of the Jeefo viral body).",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [],
  "faq_count": 0,
  "mitre_attack": [
    "T1055.001",
    "T1027",
    "T1098",
    "T1547.001",
    "T1485"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1098",
      "name": "Account Manipulation",
      "tactic": "Credential Access"
    },
    {
      "id": "T1055.001",
      "name": "Process Injection: Dynamic-link Library Injection",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1485",
      "name": "Data Destruction",
      "tactic": "Impact"
    },
    {
      "id": "T1547.001",
      "name": "Boot or Logon Autostart Execution: Registry Run Keys / Startup Folder",
      "tactic": "Persistence"
    },
    {
      "id": "T1027",
      "name": "Obfuscated Files or Information",
      "tactic": "Defense Evasion"
    }
  ],
  "containment_steps": [
    "Instantly sever the endpoint from the network to prevent the virus from iterating over open SMB shares and infecting files on central servers.",
    "Do not execute any files on the infected system, as running an infected file simply re-triggers the memory-resident infection cycle.",
    "Boot the infected machine from a known-clean, write-protected live OS (like a Linux Live USB) to safely scan and disinfect the drive offline.",
    "Utilize a specialized antivirus disinfection tool capable of carefully stripping the appended Jeefo viral body and restoring the original executable entry points."
  ],
  "what_to_avoid": [
    "Do not attempt to manually clean the machine while booted into the infected OS; the memory-resident virus will instantly reinfect files as you clean them.",
    "Avoid relying solely on file deletion; deleting infected files means deleting legitimate applications. Proper disinfection is required to save the data."
  ],
  "target_industries": [
    "Global / Opportunistic"
  ],
  "motivation": "Opportunistic",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ]
}