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SYNTHESIS OF THE VULNERABILITY

An attacker can detect if a username is valid by looking at the
pam_krb5 prompt.

Severity: 1/4

Consequences: data reading

Provenance: intranet client

Means of attack: no proof of concept, no attack

Ability of attacker: expert (4/4)

Confidence: confirmed by the editor (5/5)

Diffusion of the vulnerable configuration: high (3/3)

Creation date: 27/05/2009

IMPACTED PRODUCTS

– Red Hat Enterprise Linux

DESCRIPTION OF THE VULNERABILITY

The pam_krb5 PAM module handles the authentication using the
Kerberos protocol.

When an attacker enters a valid username, the prompt is different
than the prompt for invalid usernames.

An attacker can therefore use a brute force attack to detect valid
usernames.

CHARACTERISTICS

Identifiers: 502602, BID-35112, CVE-2009-1384, VIGILANCE-VUL-8739

http://vigilance.fr/vulnerability/pam-krb5-user-detection-8739