libgcrypt before version 1.7.8 is vulnerable to a cache side-channel attack resulting into a complete break of RSA-1024 while using the left-to-right method for computing the sliding-window expansion. The same attack is believed to work on RSA-2048 with moderately more computation. This side-channel requires that attacker can run arbitrary software on the hardware where the private RSA key is used.
The MITRE CVE dictionary describes this issue as:
Find out more about CVE-2017-7526 from the MITRE CVE dictionary dictionary and NIST NVD.
This side-channel attack requires that the attacker can run arbitrary software on the hardware where the private RSA key is used. Allowing execute access to a box with private keys should be considered as an unsafe security practice, anyway. Thus in practice there are easier ways to access the private keys than to mount this side-channel attack. However, on boxes with virtual machines this attack may be used by one VM to steal private keys from another VM.
NOTE: The following CVSS v3 metrics and score provided are preliminary and subject to review.
| CVSS3 Base Score | 6.1 |
|---|---|
| CVSS3 Base Metrics | CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:N/A:N |
| Attack Vector | Network |
| Attack Complexity | High |
| Privileges Required | None |
| User Interaction | Required |
| Scope | Changed |
| Confidentiality | High |
| Integrity Impact | None |
| Availability Impact | None |
| Platform | Package | State |
|---|---|---|
| Red Hat Enterprise Linux 7 | libgcrypt | Will not fix |
| Red Hat Enterprise Linux 6 | libgcrypt | Will not fix |
| Red Hat Enterprise Linux 5 | libgcrypt | Will not fix |
| RHEV Manager 3 | mingw-virt-viewer | Will not fix |
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