Authentication bypass in heimdal (Alpine package)

Published: 2017-07-18

Risk	Low
Patch available	YES
Number of vulnerabilities	1
CVE-ID	CVE-2017-11103
CWE-ID	CWE-311
Exploitation vector	Local network
Public exploit	N/A
Vulnerable software Subscribe	heimdal (Alpine package) Operating systems & Components / Operating system package or component
Vendor	Alpine Linux Development Team

Security Bulletin

This security bulletin contains one low risk vulnerability.

1) Authentication bypass

EUVDB-ID: #VU7482

Risk: Low

CVSSv3.1: 5.7 [CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-11103

CWE-ID: CWE-311 - Missing Encryption of Sensitive Data

Exploit availability: No

Description

The vulnerability allows a remote attacker to impersonate a trusted server and intercept users' credentials.

The vulnerability exists due to the KDC-REP service name is stored in unencrypted "ticket" instead of encrypted "enc_part" and used later by the _krb5_extract_ticket() function. An attacker in local network can perform a man-in-the-middle attack, intercept the KDC-REP service name and impersonate a trusted server.

Successful exploitation of the vulnerability may allow an attacker to obtain credentials of all Samba users from Samba DRS replication service during password replication process between trusted and fake DC.

Mitigation

Install update from vendor's website.

Vulnerable software versions

heimdal (Alpine package): 1.6_rc2-r4 - 1.6_rc2-r5

External links

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.