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2021-04 Security Bulletin: Junos OS: J-Web has an Improper Neutralization of CRLF Sequences in its HTTP Headers which allows an attacker to carry out multiple types of attacks. (CVE-2021-0268)

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Article ID: JSA11159 SECURITY_ADVISORIES Last Updated: 14 Apr 2021Version: 1.0
Product Affected:
This issue affects Junos OS 18.1, 18.2, 18.3, 18.4, 19.1, 19.2, 19.3, 19.4, 20.1.
Problem:

An Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Response Splitting') weakness in J-web of Juniper Networks Junos OS leads to buffer overflows, segment faults, or other impacts, which allows an attacker to modify the integrity of the device and exfiltration information from the device without authentication. The weakness can be exploited to facilitate cross-site scripting (XSS), cookie manipulation (modifying session cookies, stealing cookies) and more. This weakness can also be exploited by directing a user to a seemingly legitimate link from the affected site. The attacker requires no special access or permissions to the device to carry out such attacks.

This issue affects:

Juniper Networks Junos OS:

  • 18.1 versions prior to 18.1R3-S11;
  • 18.2 versions prior to 18.2R3-S5;
  • 18.3 versions prior to 18.3R2-S4, 18.3R3-S3;
  • 18.4 versions prior to 18.4R2-S5, 18.4R3-S3;
  • 19.1 versions prior to 19.1R2-S2, 19.1R3-S2;
  • 19.2 versions prior to 19.2R1-S5, 19.2R2;
  • 19.3 versions prior to 19.3R3;
  • 19.4 versions prior to 19.4R1-S3, 19.4R2, 19.4R3;
  • 20.1 versions prior to 20.1R1-S2, 20.1R2.
  • This issue does not affect Juniper Networks Junos OS versions prior to 18.1R1.

The following minimal configuration is necessary:

[system services web-management http]

or

[system services web-management https]

Juniper SIRT is not aware of any malicious exploitation of this vulnerability.

This issue was found during internal product security testing or research.

This issue has been assigned CVE-2021-0268.

Solution:

The following software releases have been updated to resolve this specific issue: 18.1R3-S11, 18.2R3-S5, 18.3R2-S4, 18.3R3-S3, 18.4R2-S5, 18.4R3-S3, 19.1R2-S2, 19.1R3-S2, 19.2R1-S5, 19.2R2, 19.3R3, 19.4R1-S3, 19.4R2, 19.4R3, 20.1R1-S2, 20.1R2, 20.2R1, and all subsequent releases.

This issue is being tracked as 1503569.

Workaround:

There are no viable workarounds for this issue other than disabling the J-Web service.

To reduce the risk of exploitation utilize common security BCPs to limit the exploitable surface by limiting access to network and device to trusted systems, administrators, networks and hosts.

Implementation:
Software releases or updates are available for download at https://support.juniper.net/support/downloads/
Modification History:
2021-04-14: Initial Publication.
CVSS Score:
8.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:L)
Severity Level:
High
Severity Assessment:
Information for how Juniper Networks uses CVSS can be found at KB 16446 "Common Vulnerability Scoring System (CVSS) and Juniper's Security Advisories."

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