#StopRansomware: Hive Ransomware
In some cases, Hive actors have bypassed multifactor authentication (MFA) and gained access to FortiOS servers by exploiting Common Vulnerabilities and Exposures (CVE) CVE-2020-12812.
CVE-2020-12812 KEVRansomware Critical · 9.8 EPSS 45.4%
Fortinet FortiOS SSL VPN Improper Authentication Vulnerability
Fortinet · FortiOS
Summary
The flaw is an improper authentication weakness in the SSL VPN component of Fortinet's FortiOS. An attacker who changes the case of their username can log in without being prompted for the second factor (FortiToken), which requires only network access to the SSL VPN and valid credentials for the account.
Official description · NVD
An improper authentication vulnerability in SSL VPN in FortiOS 6.4.0, 6.2.0 to 6.2.3, 6.0.9 and below may result in a user being able to log in successfully without being prompted for the second factor of authentication (FortiToken) if they changed the case of their username.
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
78.5 / 100
- Exploited
- Yes, in CISA KEV
- Reports
- 1
- Tactics
- 3/15
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
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 8 months after disclosure.
- Disclosedday 0
- First seen exploitedVulnCheck KEV evidence+8 mo
- Added to CISA KEVknown ransomware use; EU database agrees+15 mo
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
1 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 1PersistenceTA0003
MITRE CTID mapping of the KEV entry · how it is exploited
CVE-2020-12812 is an improper authentication vulnerability in Fortinet's FortiOS, specifically affecting the SSL VPN feature. This vulnerability allows attackers to bypass two-factor authentication under certain conditions, potentially leading to unauthorized access to sensitive systems.
Detection
0 rules for this CVE · 12 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-2020-12812 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.
Modify Authentication ProcessT155612 general rules
- AWS Identity Center Identity Provider Changehightest
- Directory Service Restore Mode(DSRM) Registry Value Tamperinghightest
- Github High Risk Configuration Disabledhightest
- Possible Shadow Credentials Addedhightest
- CA Policy Removed by Non Approved Actormediumtest
- CA Policy Updated by Non Approved Actormediumtest
- Certificate-Based Authentication Enabledmediumtest
- Change to Authentication Methodmediumtest
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Named in 1 threat report1 reportCISA
Reports are matched by finding the exact id CVE-2020-12812 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.
- Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
- Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
- Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
- Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
- Actively_Exploited_Kev | Oct 23, 202622 Oct 2026
- Actively_Exploited_Kev | Oct 22, 202621 Oct 2026
- 44 more on OTX