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2022-01 Security Bulletin: Junos OS: SRX Series: Multiple vulnerabilities in traffic classification when 'no-syn-check' is enabled (CVE-2022-22157, CVE-2022-22167)

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Article ID: JSA11265 SECURITY_ADVISORIES Last Updated: 12 Jan 2022Version: 2.0
Product Affected:
These issues affect Junos OS 18.4, 19.1, 19.2, 19.3, 19.4, 20.1, 20.2, 20.3, 20.4, 21.1, 21.2. Affected platforms: SRX Series.
Problem:

Multiple traffic classification vulnerabilities in Juniper Networks Junos OS on the SRX Series Services Gateways may allow an attacker to bypass Juniper Deep Packet Inspection (JDPI) rules and access unauthorized networks or resources, when 'no-syn-check' is enabled on the device. In one case, JDPI incorrectly classifies out-of-state asymmetric TCP flows as the dynamic-application INCONCLUSIVE instead of UNKNOWN, which is more permissive. A second issue was discovered where the dynamic-application classification is not properly provided to the policy module and hence traffic continues to use the pre-id-default-policy. In both cases, without the combination of fixes, the firewall allows traffic to be forwarded that should have been denied. causing the firewall to allow traffic to be forwarded that should have been denied.

These issues only occur when 'set security flow tcp-session no-syn-check' is configured on the device.

One or more of these issues affect Juniper Networks Junos OS on SRX Series:

  • 18.4 versions prior to 18.4R2-S10, 18.4R3-S10;
  • 19.1 versions prior to 19.1R3-S8;
  • 19.2 versions prior to 19.2R1-S8, 19.2R3-S4;
  • 19.3 versions prior to 19.3R3-S3;
  • 19.4 versions prior to 19.4R3-S5;
  • 20.1 versions prior to 20.1R3-S1;
  • 20.2 versions prior to 20.2R3-S2;
  • 20.3 versions prior to 20.3R3-S1;
  • 20.4 versions prior to 20.4R2-S2, 20.4R3;
  • 21.1 versions prior to 21.1R2-S2, 21.1R3;
  • 21.2 versions prior to 21.2R2.

These issues do not affect Juniper Networks Junos OS versions prior to 18.4R1.


These issues will only be seen when the following configuration is present:

[security flow tcp-session no-syn-check]


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

These issues were seen during production usage.


The following issues have been reported and resolved:

CVE CVSS Summary
CVE-2022-22157 7.2 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N) A traffic classification vulnerability in Juniper Networks Junos OS on the SRX Series Services Gateways may allow an attacker to bypass Juniper Deep Packet Inspection (JDPI) rules and access unauthorized networks or resources, when 'no-syn-check' is enabled on the device. JDPI incorrectly classifies out-of-state asymmetric TCP flows as the dynamic-application INCONCLUSIVE instead of UNKNOWN, which is more permissive, causing the firewall to allow traffic to be forwarded that should have been denied. This issue only occurs when 'set security flow tcp-session no-syn-check' is configured on the device.
CVE-2022-22167 7.2 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N) A traffic classification vulnerability in Juniper Networks Junos OS on the SRX Series Services Gateways may allow an attacker to bypass Juniper Deep Packet Inspection (JDPI) rules and access unauthorized networks or resources, when 'no-syn-check' is enabled on the device. While JDPI correctly classifies out-of-state asymmetric TCP flows as the dynamic-application UNKNOWN, this classification is not provided to the policy module properly and hence traffic continues to use the pre-id-default-policy, which is more permissive, causing the firewall to allow traffic to be forwarded that should have been denied. This issue only occurs when 'set security flow tcp-session no-syn-check' is configured on the device.
Solution:

The following software releases have been updated to resolve both issues: Junos OS 18.4R2-S10, 18.4R3-S10, 19.1R3-S8, 19.2R1-S8, 19.2R3-S4, 19.3R3-S3, 19.4R3-S5, 20.1R3-S1, 20.2R3-S2, 20.3R3-S1, 20.4R2-S2, 20.4R3, 21.1R2-S2, 21.1R3, 21.2R2, 21.3R1, and all subsequent releases.

Notes:

  1. The original issue was first introduced in Junos OS 18.4R1.
     
  2. PR 1561533 was resolved in Junos OS 18.4R2-S9, 18.4R3-S9, 19.1R2-S3, 19.1R3-S6, 19.2R1-S7, 19.2R3-S3, 19.3R2-S6, 19.3R3-S2, 19.4R2-S5, 19.4R3-S3, 20.1R2-S2, 20.1R3, 20.2R3-S1, 20.3R3, 20.4R2-S1, 20.4R3, 21.1R1-S1, 21.1R2, 21.2R1
     
  3. PR 1599053 was resolved in Junos OS 18.4R2-S10, 18.4R3-S10, 19.1R3-S8, 19.2R1-S8, 19.2R3-S4, 19.3R3-S3, 19.4R3-S5, 20.1R3-S1, 20.2R3-S2, 20.3R3-S1, 20.4R2-S2, 20.4R3, 21.1R2-S2, 21.1R3, 21.2R2, 21.3R1, 21.4R1

Both PRs are resolved in the releases listed above.

These issues are being tracked as 1561533 and 1599053.
 

Workaround:

Either of the following workarounds will mitigate these issues:

  1. Remove 'security flow tcp-session no-syn-check' from the configuration.
  2. Enable AppID cache configuration:
    set services application-identification application-system-cache security-services
Implementation:
Software releases or updates are available for download at https://support.juniper.net/support/downloads/
 
Modification History:
2022-01-12: Initial Publication.
 
CVSS Score:
7.2 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N)
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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