CVE-2017-3738: Infoleak
OpenSSL could allow a remote attacker to obtain sensitive information, caused by an overflow bug in the AVX2 Montgomery multiplication procedure used in exponentiation with 1024-bit moduli. An attacker could exploit this vulnerability to obtain information about the private key.
Note: In order to exploit this vulnerability, the server would have to share the DH1024 private key among multiple clients, which is no longer an option since CVE-2016-0701.
Other sources
There is an overflow bug in the AVX2 Montgomery multiplication procedure used in exponentiation with 1024-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH1024 are considered just feasible, because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be significant. However, for an attack on TLS to be meaningful, the server would have to share the DH1024 private key among multiple clients, which is no longer an option since CVE-2016-0701.
This only affects processors that support the AVX2 but not ADX extensions like Intel Haswell (4th generation).
Note: The impact from this issue is similar to CVE-2017-3736, CVE-2017-3732 and CVE-2015-3193.
External References:
https://www.openssl.org/news/secadv/20171207.txt
— Red Hat
There is an overflow bug in the AVX2 Montgomery multiplication procedure used in exponentiation with 1024-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH1024 are considered just feasible, because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be significant. However, for an attack on TLS to be meaningful, the server would have to share the DH1024 private key among multiple clients, which is no longer an option since CVE-2016-0701. This only affects processors that support the AVX2 but not ADX extensions like Intel Haswell (4th generation). Note: The impact from this issue is similar to CVE-2017-3736, CVE-2017-3732 and CVE-2015-3193. OpenSSL version 1.0.2-1.0.2m and 1.1.0-1.1.0g are affected. Fixed in OpenSSL 1.0.2n. Due to the low severity of this issue we are not issuing a new release of OpenSSL 1.1.0 at this time. The fix will be included in OpenSSL 1.1.0h when it becomes available. The fix is also available in commit e502cc86d in the OpenSSL git repository.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is CVE-2017-3738?
CVE-2017-3738 is a vulnerability in OpenSSL that could allow a remote attacker to obtain sensitive information caused by an overflow bug in the AVX2 Montgomery multiplication procedure.
Which software versions are affected by CVE-2017-3738?
Versions 1.0.2 up to and excluding 1.1.0 of OpenSSL, as well as certain versions of Node.js and IBM Security Verify Governance, are affected by CVE-2017-3738.
What is the severity of CVE-2017-3738?
The severity of CVE-2017-3738 is medium, with a CVSS score of 5.9.
Are RSA and DSA algorithms affected by CVE-2017-3738?
No, analysis suggests that attacks against RSA and DSA as a result of this vulnerability would be very difficult to perform and are not believed likely.
Where can I find more information about CVE-2017-3738?
You can find more information about CVE-2017-3738 on the Red Hat website: [link1], [link2], [link3].