Slefdel

Overview

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.

Understanding Slefdel (Self-Deleting Droppers)
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.

Execution and Evasion Mechanics
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.

Indicators of Compromise & Impact
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.

MITRE ATT&CK Techniques

Observed techniques used by this family, mapped to the MITRE ATT&CK framework:

Tactical Mitigations

Based on the techniques used by this family, consider the following defensive strategies:

• T1059.003: Restrict execution of Windows Command Shell (cmd.exe) and block unauthorized batch scripts.
• T1105: Implement network intrusion detection systems (NIDS) and host-based firewalls to block unauthorized inbound or outbound file transfers.

Generated Detections (Boilerplate)

These YARA and Sigma rules are auto-generated based on the family name and aliases. They must be heavily tuned before deployment in a production environment.

YARA Rule

rule MALWARE_WIN_SLEFDEL {
    meta:
        description = "Detects Slefdel (ransomware)"
        author = "SystemHelpdesk Boilerplate Generator"
        date = "2026-07-06"
    strings:
        $s1 = "slefdel" ascii wide nocase
    condition:
        uint16(0) == 0x5a4d and any of them
}

Sigma Rule

title: Suspicious Slefdel Activity
id: 5d32a8f68d007999944f4d27958f5b80
status: experimental
description: Detects generic indicators of the slefdel malware family.
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmd.exe'
            - '\powershell.exe'
        CommandLine|contains:
            - "*slefdel*"
    condition: selection
level: medium

Containment & Response Steps

Ordered checklist for responders. Adapt to your environment and engage professional support for active incidents.

1. Isolate the endpoint immediately; the self-deletion indicates a successful drop of a secondary, likely more dangerous, payload.
2. Analyze EDR process telemetry meticulously to identify the exact actions taken by the file *before* it spawned the deletion command.
3. Hunt for newly created files or anomalous registry keys (autostarts) created around the exact timestamp of the self-deletion event.
4. If possible, recover the deleted dropper executable from volume shadow copies or network packet captures for reverse engineering.

What to Avoid

Common mistakes during response to this family that can destroy evidence, spread the infection, or worsen recovery.

1. 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.
2. Avoid rebooting the machine immediately, as you may lose critical volatile memory containing the *actual* running payload.

References & External Analysis

• Search "slefdel" on VirusTotal (External Analysis)

Frequently Asked Questions

Related Families (Category: ransomware)

Explore other malware families in the same category:

• Danabot
• Minimal
• Dllhijacker
• Omyaamfbexii
• Nabasa

Machine-readable

Get this profile as JSON: https://jordan123234-malware-families-explorer.static.hf.space/api/slefdel.json

Ecosystem & Interactive Environments

This profile is part of the Malware Families Catalog, a public dataset of 2,899 malware families. The catalog is also published across our ecosystem: Hugging Face, Kaggle, Zenodo, Replit, StackBlitz, CodeSandbox, and CodePen.