FreeBSD : pycrypto -- vulnerable ElGamal key generation (f45c0049-be72-11e1-a284-0023ae8e59f0)

NASLDB: FreeBSD : pycrypto -- vulnerable ElGamal key generation (f45c0049-be72-11e1-a284-0023ae8e59f0)

General

ID: 59700
Name: FreeBSD : pycrypto — vulnerable ElGamal key generation (f45c0049-be72-11e1-a284-0023ae8e59f0)

Summary: Checks for updated package in pkg_info output

Credits: Tenable Network Security, Inc.

Classification

Risk: –

CVSS: –
CVSS Base Vector: CVSS2#AV:N/AC:M/Au:N/C:N/I:P/A:N
CVSS Temporal Vector: –

Port: 0
Family: FreeBSD Local Security Checks
Type: Local

Description

Dwayne C. Litzenberger of PyCrypto reports :

In the ElGamal schemes (for both encryption and signatures), g is
supposed to be the generator of the entire Z^*_p group. However, in
PyCrypto 2.5 and earlier, g is more simply the generator of a random
sub-group of Z^*_p.

The result is that the signature space (when the key is used for
signing) or the public key space (when the key is used for encryption)
may be greatly reduced from its expected size of log(p) bits, possibly
down to 1 bit (the worst case if the order of g is 2).

While it has not been confirmed, it has also been suggested that an
attacker might be able to use this fact to determine the private key.

Anyone using ElGamal keys should generate new keys as soon as
practical.

Any additional information about this bug will be tracked at
https://bugs.launchpad.net/pycrypto/+bug/985164

Exploiting

Exploit Available: –
Exploitability Ease: –

Sources

CVE: CVE-2012-2417
OSVDB: –
Bugtraq: –
scipID: –

Timeline

Vulnerability Disclosure: 2012/05/24
Patch Release: 2012/06/24
Plugin Release: 2012/06/26

Plugin

Version: 1.1
Filename: freebsd_pkg_f45c0049be7211e1a2840023ae8e59f0.nasl
Filesize: 5018 bytes
MD5 Hash: 8887fc3e807e4f050e2c4df297116250

Identification: Host/local_checks_enabled
Require Keys: Host/local_checks_enabled", "Host/FreeBSD/release", "Host/FreeBSD/pkg_info
Dependencies: "ssh_get_info.nasl"