Debian LTS: Security Advisory for samba (DLA-2668-1)

Published: 2021-05-30 03:00:14
CVE Author: NIST National Vulnerability Database

CVSS Base Vector:
AV:N/AC:L/Au:N/C:P/I:P/A:N

Summary:
The remote host is missing an update for the 'samba' Linux Distribution Package(s) announced via the DLA-2668-1 advisory.

Detection Method:
Checks if a vulnerable Linux Distribution Package version is present on the target host.

Technical Details:
Several vulnerabilities were discovered in Samba, SMB/CIFS file, print, and login server for Unix CVE-2019-10218 A flaw was found in the samba client, where a malicious server can supply a pathname to the client with separators. This could allow the client to access files and folders outside of the SMB network pathnames. An attacker could use this vulnerability to create files outside of the current working directory using the privileges of the client user. CVE-2019-14833 A flaw was found in Samba, in the way it handles a user password change or a new password for a samba user. The Samba Active Directory Domain Controller can be configured to use a custom script to check for password complexity. This configuration can fail to verify password complexity when non-ASCII characters are used in the password, which could lead to weak passwords being set for samba users, making it vulnerable to dictionary attacks. CVE-2019-14847 A flaw was found in samba where an attacker can crash AD DC LDAP server via dirsync resulting in denial of service. Privilege escalation is not possible with this issue. CVE-2019-14861 Samba have an issue, where the (poorly named) dnsserver RPC pipe provides administrative facilities to modify DNS records and zones. Samba, when acting as an AD DC, stores DNS records in LDAP. In AD, the default permissions on the DNS partition allow creation of new records by authenticated users. This is used for example to allow machines to self-register in DNS. If a DNS record was created that case-insensitively matched the name of the zone, the ldb_qsort() and dns_name_compare() routines could be confused into reading memory prior to the list of DNS entries when responding to DnssrvEnumRecords() or DnssrvEnumRecords2() and so following invalid memory as a pointer. CVE-2019-14870 Samba have an issue, where the S4U (MS-SFU) Kerberos delegation model includes a feature allowing for a subset of clients to be opted out of constrained delegation in any way, either S4U2Self or regular Kerberos authentication, by forcing all tickets for these clients to be non-forwardable. In AD this is implemented by a user attribute delegation_not_allowed (aka not-delegated), which translates to disallow-forwardable. However the Samba AD DC does not do that for S4U2Self and does set the forwardable flag even if the impersonated client has the not-delegated flag set. CVE-2019-14902 There is an issue in samba, where the removal of the right to create or modify a subtree would not automatically be taken away on all domain controllers. CVE-2019-14907 samba have an issue where if it is set ... Description truncated. Please see the references for more information.

Affected Versions:
'samba' Linux Distribution Package(s) on Debian Linux.

Recommendations:
For Debian 9 stretch, these problems have been fixed in version 2:4.5.16+dfsg-1+deb9u4. We recommend that you upgrade your samba Linux Distribution Packages.

Solution Type:
Vendor Patch

Detection Type:
Linux Distribution Package

NIST (National Institute of Standards and Technology) NVD (National Vulnerability Database)

https://nvd.nist.gov/vuln/detail/CVE-2019-10218
https://nvd.nist.gov/vuln/detail/CVE-2019-14833
https://nvd.nist.gov/vuln/detail/CVE-2019-14847
https://nvd.nist.gov/vuln/detail/CVE-2019-14861
https://nvd.nist.gov/vuln/detail/CVE-2019-14870
https://nvd.nist.gov/vuln/detail/CVE-2019-14902
https://nvd.nist.gov/vuln/detail/CVE-2019-14907
https://nvd.nist.gov/vuln/detail/CVE-2021-20254

References:

https://lists.debian.org/debian-lts-announce/2021/05/msg00023.html
https://security-tracker.debian.org/tracker/DLA-2668-1

https://bugs.debian.org/946786

Severity
Medium
CVSS Score
6.4
Published
2021-05-30
Modified
2021-06-01
Category
Debian Local Security Checks

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