Debian update for libgcrypt20

1) Memory-cache side-channel attack

EUVDB-ID: #VU13370

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 - Exposure of sensitive information to an unauthorized actor

Exploit availability: Yes

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 the affected package to version: 1.7.6-2+deb9u3

Vulnerable software versions

Debian Linux: All versions

CPE2.3

• cpe:2.3:o:debian:debian_linux:*:*:*:*:*:*:*:*

External links

https://www.debian.org/security/2018/dsa-4231

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.