REDHAT-BUG-2227852: Low severity OpenSSL OpenSSL vulnerability
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OpenSSL Security Advisory [31st July 2023] ==========================================
Excessive time spent checking DH q parameter value (CVE-2023-3817) ==================================================================
Severity: Low
Issue summary: Checking excessively long DH keys or parameters may be very slow.
Impact summary: Applications that use the functions DHcheck(), DHcheckex() or EVPPKEYparamcheck() to check a DH key or DH parameters may experience long delays. Where the key or parameters that are being checked have been obtained from an untrusted source this may lead to a Denial of Service.
The function DHcheck() performs various checks on DH parameters. After fixing CVE-2023-3446 it was discovered that a large q parameter value can also trigger an overly long computation during some of these checks. A correct q value, if present, cannot be larger than the modulus p parameter, thus it is unnecessary to perform these checks if q is larger than p.
An application that calls DHcheck() and supplies a key or parameters obtained from an untrusted source could be vulnerable to a Denial of Service attack.
The function DHcheck() is itself called by a number of other OpenSSL functions. An application calling any of those other functions may similarly be affected. The other functions affected by this are DHcheckex() and EVPPKEYparamcheck().
Also vulnerable are the OpenSSL dhparam and pkeyparam command line applications when using the "-check" option.
The OpenSSL SSL/TLS implementation is not affected by this issue.
The OpenSSL 3.0 and 3.1 FIPS providers are not affected by this issue.
OpenSSL 3.1, 3.0, 1.1.1 and 1.0.2 are vulnerable to this issue.
Due to the low severity of this issue we are not issuing new releases of OpenSSL at this time. The fix will be included in the next releases when they become available. The fix is also available in commit 6a1eb62c2 (for 3.1), commit 9002fd073 (for 3.0) and commit 91ddeba0f (for 1.1.1) in the OpenSSL git repository. It is available to premium support customer in commit 869ad69a (for 1.0.2).
This issue was reported on 20th July 2023 by Bernd Edlinger. The fix was developed by Tomas Mraz.
General Advisory Notes ======================
URL for this Security Advisory: https://www.openssl.org/news/secadv/20230731.txt
Note: the online version of the advisory may be updated with additional details over time.
For details of OpenSSL severity classifications please see: https://www.openssl.org/policies/secpolicy.html
OpenSSL 1.1.1 will reach end-of-life on 2023-09-11. After that date security fixes for 1.1.1 will only be available to premium support customers. -----BEGIN PGP SIGNATURE-----
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Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
OpenSSLto a version that resolves this vulnerability.Patch CVE-2023-3446 - Upgrade
Upgrade
OpenSSLto a version that resolves this vulnerability.Patch CVE-2023-3817 - Upgrade
Upgrade
OpenSSLto a version that resolves this vulnerability.Patch commit 6a1eb62c2 (for 3.1) - Upgrade
Upgrade
OpenSSLto a version that resolves this vulnerability.Patch commit 9002fd073 (for 3.0) - Upgrade
Upgrade
OpenSSLto a version that resolves this vulnerability.Patch commit 91ddeba0f (for 1.1.1) - Compensating control
Avoid invoking OpenSSL DH key/parameter validation functions on attacker-controlled or untrusted DH values (e.g., do not call DH_check(), DH_check_ex(), EVP_PKEY_param_check() or related DH parameter checks with keys/parameters obtained from an untrusted source), since excessive computation can lead to a Denial of Service.
Event History
Frequently Asked Questions
What is the severity of REDHAT-BUG-2227852?
The severity of REDHAT-BUG-2227852 is classified as high due to potential excessive resource consumption resulting from DH parameter validation.
How do I fix REDHAT-BUG-2227852?
To fix REDHAT-BUG-2227852, upgrade to OpenSSL version 1.1.1 or later to ensure proper handling of DH parameters.
What systems are affected by REDHAT-BUG-2227852?
REDHAT-BUG-2227852 affects OpenSSL versions between 1.0.2 and 1.1.1.
What exploit does REDHAT-BUG-2227852 address?
REDHAT-BUG-2227852 addresses an exploit that allows for excessive resource consumption during DH parameter validation, potentially leading to denial of service.
Is there a workaround for REDHAT-BUG-2227852?
A temporary workaround for REDHAT-BUG-2227852 may involve implementing strict validation rules for DH parameters until the software is updated.