SB2015121701 - Two backdoors in Juniper ScreenOS
Published: December 17, 2015 Updated: October 2, 2025
Security Bulletin ID
SB2015121701
CSH Severity
Critical
Patch available
YES
Number of vulnerabilities
2
Exploitation vector
Remote access
Highest impact
Code execution
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 2 vulnerabilities.
1) Authentication bypass (CVE-ID: CVE-2015-7755)
CWE-ID: CWE-287 - Improper Authentication
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Red
The vulnerability allows a remote attacker to bypass authentication on the target system.
The weakness exists due to presence of backdoor in Juniper ScreenOS code. A remote attacker can enter a password "<<< %s(un='%s') = %u" during a SSH or TELNET session and obtain administrative access to the device.
Successful exploitation of the vulnerability results in unauthorized access to the vulnerable system.
Note: the vulnerability was being actively exploited.
2) Information disclosure (CVE-ID: CVE-2015-7756)
CWE-ID: CWE-327 - Use of a Broken or Risky Cryptographic Algorithm
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:A/U:Amber
The vulnerability allows a remote attacker to obtain potentially sensitive information on the target system.
The weakness exists due to usage of insecure encryption keys. A remote attacker can with ability to monitor VPN traffic can intercept and decrypt it.
Successful exploitation of the vulnerability results in information disclosure on the target system.
Note: the vulnerability was disclosed as part of two backdoors during internal source code audit.
Remediation
Install update from vendor's website.