Juniper ScreenOS Improper Authentication Vulnerability
Juniper · ScreenOS
Juniper ScreenOS versions 6.2.0r15 through 6.2.0r18 and several 6.3.0 builds contain an improper authentication flaw in the SSH and TELNET login handling. An attacker can obtain administrative access by entering an unspecified password during an SSH or TELNET session, requiring only network access to the device and no prior authentication or user interaction.
Juniper ScreenOS 6.2.0r15 through 6.2.0r18, 6.3.0r12 before 6.3.0r12b, 6.3.0r13 before 6.3.0r13b, 6.3.0r14 before 6.3.0r14b, 6.3.0r15 before 6.3.0r15b, 6.3.0r16 before 6.3.0r16b, 6.3.0r17 before 6.3.0r17b, 6.3.0r18 before 6.3.0r18b, 6.3.0r19 before 6.3.0r19b, and 6.3.0r20 before 6.3.0r21 allows remote attackers to obtain administrative access by entering an unspecified password during a (1) SSH or (2) TELNET session.
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 5/15
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
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 4 days after disclosure. Public exploit code (PoC-in-GitHub) was available 1 day before disclosure.
- Public exploit codePoC-in-GitHub1 day before
- Disclosedday 0
- First seen exploitedVulnCheck KEV evidence+4 days
- Added to CISA KEVEU database agrees+10 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
2 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, 2 cited passages 2Initial AccessTA0001
Backdoor password grants admin access remotely over SSH/TELNET
allows remote attackers to obtain administrative access by entering an unspecified password during a (1) SSH or (2) TELNET session
Lateral MovementTA0008
Remote SSH session provides administrative control of device
allows remote attackers to obtain administrative access by entering an unspecified password during a (1) SSH or (2) TELNET session
Lower-confidence links (1)
These come from early or generic mappings, text matching, or contradict this CVE’s details (for example a public-facing technique on a bug that needs a user to open a file). Shown for completeness.
- Exploitation for StealthT1211 CTID attack_to_cve Phase 1 "Uncategorized" mapping (not staged by impact)
Detection
0 rules for this CVE · 61 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-2015-7755 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.
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
SSHT1021.0045 general rules
- Bitbucket Global SSH Settings Changedmediumtest
- Bitbucket User Login Failure Via SSHmediumtest
- OpenSSH Server Listening On Socketmediumtest
- Port Forwarding Activity Via SSH.EXEmediumtest
- OpenEDR Spawning Command Shellmediumexperimental
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Not named in any threat report yetAlso 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