#VU13370 Memory-cache side-channel attack in Libgcrypt - CVE-2018-0495

Vulnerability identifier: #VU13370

Vulnerability risk: Low

CVSSv4.0: 1.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P/U:Clear]

CVE-ID: CVE-2018-0495

CWE-ID: CWE-200

Exploitation vector: Local

Exploit availability: Yes

Vulnerable software:
Libgcrypt
Client/Desktop applications / Encryption software

Vendor: GNU

Description

The vulnerability allows a local attacker to obtain potentially sensitive information.

The vulnerability exists due to a leakage of information through memory caches when the affected library uses a private key to create Elliptic Curve Digital Signature Algorithm (ECDSA) signatures.  A local attacker can conduct a memory-cache side-channel attack on ECDSA signatures and recover sensitive information, such as ECDSA private keys, which could be used to conduct further attacks. 

Note: The vulnerability is known as the "Return Of the Hidden Number Problem" or ROHNP.

Mitigation
Update to version 1.7.10, 1.8.3.

Vulnerable software versions

Libgcrypt: 1.5.0 - 1.8.2

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External links
http://lists.gnupg.org/pipermail/gnupg-announce/2018q2/000426.html

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.