The problem of negative dentries accumulating in the dentry cache in an
unbounded manner, as we looked at back in
April, came up at the
2022 Linux Storage,
Filesystem, Memory-management and BPF Summit (LSFMM).
Negative dentries reflect failed file-name lookups, which are then cached,
saving an expensive operation if the file name in question is looked up
again. There is no mechanism to proactively prune back those cache
entries, however, so the cache keeps growing until memory pressure finally
causes the system to forcibly evict some of them, which can make the system
unresponsive for a long time or even cause a soft lockup.
Intelligence View
⚡ tsecurity.de Intelligence
[$] Dealing with negative dentries
The problem of negative dentries accumulating in the dentry cache in an unbounded manner, as we looked at back in April, came up at the 2022 Linux Storage, Filesystem, Memory-management and BPF Summit (LSFMM). Negative dentries reflect…
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IR-PLAYBOOK-VULN-REMEDIATIONMEDIUM
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SOC Incident Playbook: Vulnerability Remediation & Verification
1-Click Detection Engineering: Multi-Dialect SIEM Rules5 Formate
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Syntax validiert (0 Fehler)
title: Detect Exploitation - [$] Dealing with negative dentries
id: 166a855a-dae8-4283-ba3f-77b4e63d7768
status: experimental
description: Automatisch generierte SIEM-Erkennungsregel basierend auf CTI Intelligence
references:
- https://tsecurity.de/
author: iShareStuff CTI Automated Detection Engine
date: 2026-09-25
logsource:
category: network_connection
product: any
detection:
selection:
CommandLine|contains:
- 'exploit'
condition: selection
falsepositives:
- Legitime administrative Zugriffe oder Penetrationstests
level: high
tags:
- attack.initial_accessSyntax validiert (0 Fehler)
rule CTI_Threat_Indicator {
meta:
author = "iShareStuff CTI Automated Detection Engine"
date = "2026-09-25"
description = "YARA Signature for "
strings:
$str = "[$] Dealing with negative dent" ascii wide
condition:
any of them
}Syntax validiert (0 Fehler)
index=security sourcetype IN ("cisco:asa", "pan:traffic", "zeek_conn", "suricata", "WinEventLog:Security")
("Dealing with negative dentries")
| stats count earliest(_time) as first_seen latest(_time) as last_seen by src_ip, dest_ip, dest_host, signature
| eval first_seen=strftime(first_seen, "%Y-%m-%d %H:%M:%S"), last_seen=strftime(last_seen, "%Y-%m-%d %H:%M:%S")
| sort - countSyntax validiert (0 Fehler)
message: "*Dealing with negative dentries*"Syntax validiert (0 Fehler)
CommonSecurityLog
| where Message has "Dealing with negative dentries"
| summarize EventCount = count(), FirstSeen = min(TimeGenerated), LastSeen = max(TimeGenerated) by SourceIP, DestinationIP, DestinationPort, Activity
| extend DetectionRule = "iShareStuff-CTI-Compiled"
| sort by EventCount desc2. Cyber Threat Intelligence & Forensik
CTI Threat Relationship Graph2 Knoten / 1 Relationen
🎯
MITRE ATT&CK Matrix Navigator 14 Taktiken
Reconnaissance
-
Resource Development
-
Initial Access
Execution
Persistence
-
Privilege Escalation
Defense Evasion
Credential Access
-
Discovery
-
Lateral Movement
-
Collection
-
Command and Control
Exfiltration
-
Impact
tsecurity.de Cognitive Threat RAG
Fokus-Vektor:
Kognitive Analyse für identifizierte Bedrohung: Erhöhte Bedrohungslage im Bereich [$] Dealing with negative dentries.... Basierend auf 368k Vektor-Korrelationen werden sofortige Isolationsmaßnahmen für betroffene Endpunkte empfohlen.
🛡️ Angriffsfläche & Exposure
Netzwerk/Remote-Zugriff ohne Vorauthentifizierung möglich.
⚡ Empfohlene Sofortmaßnahmen
- 1. Perimeter-Inspektion: Relevante Portfreigaben und exponierte Endpunkte unverzüglich scannen.
- 2. Patch-Applikation: Hersteller-Hotfix einspielen oder betroffene Daemons in isolierte DMZ-Segmente überführen.
- 3. Telemetrie & EDR-Alerts: Prozessaufrufe und Child-Processes auf anomale Shell-Spawns überwachen.
🔗 Semantisch verwandte Zero-Days
MariaDB 11.7 VEC
Synthetische RAG-Antwort