Nefilim Ransomware
Nefilim targets vulnerabilities such as CVE-2019-11634 and CVE-2019-19781 in Citrix gateway devices, identified in December 2019 and patched in January 2020.
CVE-2019-11634 KEVRansomware Critical · 9.8 EPSS 8.1%
Citrix Workspace Application and Receiver for Windows Remote Code Execution Vulnerability
Citrix · Workspace Application and Receiver for Windows
Summary
Citrix Workspace App for Windows, prior to version 1904, contains an improper access control flaw in the Workspace Application and Receiver component. An attacker who can reach the product over the network can exploit it without authentication or user interaction, with no special configuration required.
Official description · NVD
Citrix Workspace App before 1904 for Windows has Incorrect Access Control.
Priority scorePatchfirst’s 0 to 100 ranking. It adds points for CISA KEV listing, ransomware use, EPSS, threat reports, public exploit code and CVSS. Every CVE page shows the breakdown. Breakdown
77.7 / 100
- Exploited
- Yes, in CISA KEV
- Reports
- 1
- Tactics
- 9/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.How attackers get in
What they do
What can follow
Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 20 months after disclosure.
- Disclosedday 0
- First seen exploitedVulnCheck KEV evidence+20 mo
- Added to CISA KEVknown ransomware use; EU database agrees+2 yrs
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
7 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order 7Initial AccessTA0001
Valid Accounts T1078 Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details. also Persistence, Privilege Escalation, Stealth
MITRE CTID mapping of the KEV entry · follow-on activity
CVE-2019-11634 is a remote code execution vulnerability for Citrix Workspace Application and Receiver for Windows
Exploit Public-Facing Application T1190 Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.
MITRE CTID mapping of the KEV entry · how it is exploited
Vulnerability in Citrix Receiver for Windows may allows attacker to gain read/write access to the client's local drives, potentially enabling code execution on the client device, such as deploying ransomware
ExecutionTA0002
Command and Scripting Interpreter T1059 Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.
MITRE CTID mapping of the KEV entry · primary impact
Credential AccessTA0006
OS Credential Dumping T1003 Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.
MITRE CTID mapping of the KEV entry · follow-on activity
DiscoveryTA0007
Network Service Discovery T1046 Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.
MITRE CTID mapping of the KEV entry · follow-on activity
CollectionTA0009
Data from Local System T1005 Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.
MITRE CTID mapping of the KEV entry · follow-on activity
ImpactTA0040
Data Encrypted for Impact T1486 Medium Confidence (technique links)How sure Patchfirst is that an ATT&CK technique applies to this CVE. High and medium links are shown by default; low ones come from early or generic mappings, text matching, or contradict the CVE’s details.
MITRE CTID mapping of the KEV entry · follow-on activity
Detection
0 rules for this CVE · 388 general rules for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2019-11634 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Exploit Public-Facing ApplicationT1190149 general rules
- Arcadyan Router Exploitationscriticaltest
- Citrix ADS Exploitation CVE-2020-8193 CVE-2020-8195criticaltest
- Citrix Netscaler Attack CVE-2019-19781criticaltest
- Confluence Exploitation CVE-2019-3398criticaltest
- CVE-2010-5278 Exploitation Attemptcriticaltest
- CVE-2020-0688 Exchange Exploitation via Web Logcriticaltest
- CVE-2020-10148 SolarWinds Orion API Auth Bypasscriticaltest
- CVE-2020-5902 F5 BIG-IP Exploitation Attemptcriticaltest
Command and Scripting InterpreterT105995 general rules
- HackTool - Sliver C2 Implant Activity Patterncriticaltest
- Lazarus Group Activitycriticaltest
- REvil Kaseya Incident Malware Patternscriticaltest
- Turla Group Lateral Movementcriticaltest
- Windows Defender AMSI Trigger Detectedhighstable
- Windows Defender Threat Detectedhighstable
- Abusable DLL Potential Sideloading From Suspicious Locationhightest
- Add Insecure Download Source To Wingethightest
Valid AccountsT107856 general rules
- Win Susp Computer Name Containing Samtheadmincriticaltest
- Account Created And Deleted Within A Close Time Framehightest
- Activity From Anonymous IP Addresshightest
- Atypical Travelhightest
- Azure AD Threat Intelligencehightest
- Azure Subscription Permission Elevation Via AuditLogshightest
- External Remote SMB Logon from Public IPhightest
- Impossible Travelhightest
OS Credential DumpingT100337 general rules
- Antivirus - Password Dumper Signaturecriticalstable
- HackTool - Rubeus Executioncriticalstable
- Hacktool Execution - Imphashcriticaltest
- Potential Credential Dumping Via LSASS Process Clonecriticaltest
- WCE wceaux.dll Accesscriticaltest
- HackTool - Potential Remote Credential Dumping Activity Via CrackMapExec Or Impacket-Secretsdumphightest
- HackTool - Rubeus Execution - ScriptBlockhightest
- Hacktool Execution - PE Metadatahightest
Network Service DiscoveryT104620 general rules
- HackTool - winPEAS Executionhightest
- HackTool - WinPwn Executionhightest
- HackTool - WinPwn Execution - ScriptBlockhightest
- Grixba Malware Reconnaissance Activityhighexperimental
- OpenCanary - Host Port Scan (SYN Scan)highexperimental
- OpenCanary - NMAP FIN Scanhighexperimental
- OpenCanary - NMAP NULL Scanhighexperimental
- OpenCanary - NMAP OS Scanhighexperimental
Data from Local SystemT100514 general rules
- OpenCanary - SMB File Open Requesthightest
- Potential Conti Ransomware Database Dumping Activity Via SQLCmdhightest
- SQLite Chromium Profile Data DB Accesshightest
- SQLite Firefox Profile Data DB Accesshightest
- VeeamBackup Database Credentials Dump Via Sqlcmd.EXEhightest
- Script Interpreter Spawning Credential Scanner - Linuxhighexperimental
- Script Interpreter Spawning Credential Scanner - Windowshighexperimental
- Shai-Hulud NPM Package Malicious Exfiltration via Curlhighexperimental
Data Encrypted for ImpactT148617 general rules
- LockerGoga Ransomware Activitycriticalstable
- Antivirus - Ransomware Signaturecriticaltest
- Potential Conti Ransomware Activitycriticaltest
- WannaCry Ransomware Activitycriticaltest
- BlueSky Ransomware Artefactshightest
- Load Of RstrtMgr.DLL By A Suspicious Processhightest
- Renamed Gpg.EXE Executionhightest
- Suspicious Reg Add BitLockerhightest
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Named in 1 threat report1 reportblog.qualys.com
Reports are matched by finding the exact id CVE-2019-11634 in their text; nobody has reviewed the match. One passage is shown per report, at most 320 characters, linked to the original.
Also mentioned in 50 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
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