{
  "family": "slefdel",
  "sample_count": 2,
  "category": "ransomware",
  "description": "Trojan:Win32/Slefdel is a heuristic detection identifying a specific, evasive behavior common in malware droppers and initial stagers: self-deletion (`T1070.004`). This is not a specific malware family, but a tactical indicator. The malware executes, performs its primary function (usually downloading or extracting a much larger, stealthier payload), and then permanently deletes its own original executable file from the disk to eliminate the primary forensic artifact.<br><br><b>Understanding Slefdel (Self-Deleting Droppers)</b><br>To an end-user, this action is entirely invisible. For an incident responder, discovering a Slefdel alert means the initial infection vector is gone. The attacker successfully dropped a payload and then burned the bridge behind them. This requires immediate EDR analysis to determine *what* the deleted file actually did before it vanished.<br><br><b>Execution and Evasion Mechanics</b><br>Slefdel behavior is typically implemented in the initial dropper (often delivered via phishing - `T1566.001`). Upon execution, the dropper extracts the true malware payload (e.g., a banking trojan or ransomware) into memory or a hidden directory (`T1105`). To delete itself while it is still running (which Windows normally prevents), the malware uses API tricks. A common method is spawning a hidden command shell (`cmd.exe`) with a brief timeout (`ping 127.0.0.1`), instructing it to delete the dropper executable (`del /f /q`) immediately after the dropper process terminates. This leaves the victim machine infected with the payload, but the original dropped file is missing, frustrating traditional file-based AV scanning.<br><br><b>Indicators of Compromise & Impact</b><br>The impact depends entirely on the secondary payload that was dropped. The primary IoC is the EDR alert flagging the self-deletion technique. Host-based IoCs require analyzing process trees: look for an initial suspicious executable (often in `%Temp%` or `Downloads`) that spawns `cmd.exe` passing the `/c del` command targeting its own file path. Network IoCs involve identifying any outbound connections made by that initial executable *before* it deleted itself.",
  "cta": "Published by the SystemHelpdesk team.",
  "aliases": [],
  "enrichment_level": "expert-seo",
  "faq": [
    {
      "@type": "Question",
      "name": "What is Slefdel and what threat category does it belong to?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Slefdel is classified as a Ransomware. 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 Slefdel establish persistence and evade defensive controls?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Slefdel 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 Slefdel compromise?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Security teams responding to Slefdel 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 cryptographic algorithms and file targeting techniques does Slefdel employ during execution?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Slefdel typically leverages hybrid cryptographic architectures combining symmetric stream or block ciphers (such as AES-256 or ChaCha20) for rapid file encryption with asymmetric algorithms (such as RSA-2048 or Curve25519) to securely protect the session keys. It aggressively targets sensitive file extensions including corporate documents, databases, virtual disks, and backups while systematically executing commands to delete Volume Shadow Copies (vssadmin delete shadows /all /quiet) and disable system recovery options."
      }
    },
    {
      "@type": "Question",
      "name": "Are decryptors available for Slefdel, and what is the recommended recovery procedure?",
      "acceptedAnswer": {
        "@type": "Answer",
        "text": "Decryption availability for Slefdel depends on whether security researchers or law enforcement (such as the No More Ransom initiative) have recovered the master private keys or discovered flaws in its key generation routines. Victims should never pay the extortion demand, as payment fuels criminal operations without guaranteeing file restoration. The recommended recovery procedure entails isolating infected hosts, conducting forensic disk imaging, identifying the root access vector, and restoring validated systems from immutable offline backups."
      }
    }
  ],
  "faq_count": 5,
  "mitre_attack": [
    "T1070.004",
    "T1059.003",
    "T1105"
  ],
  "cisa_advisory": null,
  "last_updated": "2026-06-09",
  "mitre_attack_detail": [
    {
      "id": "T1070.004",
      "name": "Indicator Removal on Host: File Deletion (The core self-deletion behavior)",
      "tactic": "Defense Evasion"
    },
    {
      "id": "T1059.003",
      "name": "Command and Scripting Interpreter: Windows Command Shell (Using cmd.exe to execute the deletion)",
      "tactic": "Execution"
    },
    {
      "id": "T1105",
      "name": "Ingress Tool Transfer (The action performed before deletion)",
      "tactic": "Command and Control"
    }
  ],
  "containment_steps": [
    "Isolate the endpoint immediately; the self-deletion indicates a successful drop of a secondary, likely more dangerous, payload.",
    "Analyze EDR process telemetry meticulously to identify the exact actions taken by the file *before* it spawned the deletion command.",
    "Hunt for newly created files or anomalous registry keys (autostarts) created around the exact timestamp of the self-deletion event.",
    "If possible, recover the deleted dropper executable from volume shadow copies or network packet captures for reverse engineering."
  ],
  "what_to_avoid": [
    "Do not assume the threat is mitigated just because the AV scanner says the file is 'removed' or 'not found'; the malware deleted itself on purpose.",
    "Avoid rebooting the machine immediately, as you may lose critical volatile memory containing the *actual* running payload."
  ],
  "target_industries": [
    "Healthcare",
    "Critical Infrastructure",
    "Enterprise"
  ],
  "motivation": "Financial Extortion",
  "threat_actors": [
    "Unknown / Cybercriminal"
  ],
  "target_geographies": [
    "Global"
  ],
  "attack_stage": [
    "defense_evasion",
    "impact"
  ],
  "ecosystem": [
    "windows_pe"
  ],
  "is_emerging": false,
  "target_platforms": [
    "Windows 11",
    "Windows 10",
    "Windows Server 2022",
    "Windows Server 2019"
  ]
}