The remote Redhat Enterprise Linux 8 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2021:5142 advisory.

    Red Hat Identity Management (IdM) is a centralized authentication, identity management, and authorization     solution for both traditional and cloud-based enterprise environments.

    Security Fix(es):

    * samba: Samba AD DC did not always rely on the SID and PAC in Kerberos tickets (CVE-2020-25719)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Oracle Linux 8 host has packages installed that are affected by a vulnerability as referenced in the ELSA-2021-5142 advisory.

    - Hardening for CVE-2020-25717, part 3       Related: RHBZ#2021489
    - Hardening for CVE-2020-25717, part 2
    - Hardening for CVE-2020-25717

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Redhat Enterprise Linux 7 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2021:5195 advisory.

    Red Hat Identity Management (IdM) is a centralized authentication, identity management, and authorization     solution for both traditional and cloud-based enterprise environments.

    Security Fix(es):

    * samba: Samba AD DC did not always rely on the SID and PAC in Kerberos tickets (CVE-2020-25719)

    For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and     other related information, refer to the CVE page(s) listed in the References section.

    Bug Fix(es):

    * RHEL 8.6 IPA Replica Failed to configure PKINIT setup against a RHEL 7.9 IPA server (BZ#2025848)

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Scientific Linux 7 host has packages installed that are affected by a vulnerability as referenced in the SLSA-2021:5195-1 advisory.

  - samba: Samba AD DC did not always rely on the SID and PAC in Kerberos tickets (CVE-2020-25719)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote CentOS Linux 7 host has packages installed that are affected by a vulnerability as referenced in the RHSA-2021:5195 advisory.

  - A flaw was found in the way Samba, as an Active Directory Domain Controller, implemented Kerberos name-     based authentication. The Samba AD DC, could become confused about the user a ticket represents if it did     not strictly require a Kerberos PAC and always use the SIDs found within. The result could include total     domain compromise. (CVE-2020-25719)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote MiracleLinux 8 host has packages installed that are affected by a vulnerability as referenced in the AXSA:2022-3004:01 advisory.

    * samba: Samba AD DC did not always rely on the SID and PAC in Kerberos tickets (CVE-2020-25719)

Tenable has extracted the preceding description block directly from the MiracleLinux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

According to the versions of the samba packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - A flaw was found in the way samba implemented SMB1 authentication. An attacker could use this flaw to     retrieve the plaintext password sent over the wire even if Kerberos authentication was required.
    (CVE-2016-2124)

  - A flaw was found in the way Samba maps domain users to local users. An authenticated attacker could use     this flaw to cause possible privilege escalation. (CVE-2020-25717)

  - A flaw was found in the way samba, as an Active Directory Domain Controller, is able to support an RODC     (read-only domain controller). This would allow an RODC to print administrator tickets. (CVE-2020-25718)

  - A flaw was found in the way Samba, as an Active Directory Domain Controller, implemented Kerberos name-     based authentication. The Samba AD DC, could become confused about the user a ticket represents if it did     not strictly require a Kerberos PAC and always use the SIDs found within. The result could include total     domain compromise. (CVE-2020-25719)

  - Multiple flaws were found in the way samba AD DC implemented access and conformance checking of stored     data. An attacker could use this flaw to cause total domain compromise. (CVE-2020-25722)

  - A null pointer de-reference was found in the way samba kerberos server handled missing sname in TGS-REQ     (Ticket Granting Server - Request). An authenticated user could use this flaw to crash the samba server.
    (CVE-2021-3671)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

According to the versions of the samba packages installed, the EulerOS installation on the remote host is affected by the following vulnerabilities :

  - A flaw was found in the way samba implemented SMB1 authentication. An attacker could use this flaw to     retrieve the plaintext password sent over the wire even if Kerberos authentication was required.
    (CVE-2016-2124)

  - A flaw was found in the way Samba maps domain users to local users. An authenticated attacker could use     this flaw to cause possible privilege escalation. (CVE-2020-25717)

  - A flaw was found in the way samba, as an Active Directory Domain Controller, is able to support an RODC     (read-only domain controller). This would allow an RODC to print administrator tickets. (CVE-2020-25718)

  - A flaw was found in the way Samba, as an Active Directory Domain Controller, implemented Kerberos name-     based authentication. The Samba AD DC, could become confused about the user a ticket represents if it did     not strictly require a Kerberos PAC and always use the SIDs found within. The result could include total     domain compromise. (CVE-2020-25719)

  - Multiple flaws were found in the way samba AD DC implemented access and conformance checking of stored     data. An attacker could use this flaw to cause total domain compromise. (CVE-2020-25722)

Note that Tenable Network Security has extracted the preceding description block directly from the EulerOS security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote AlmaLinux 8 host has packages installed that are affected by a vulnerability as referenced in the ALSA-2021:5142 advisory.

    * samba: Samba AD DC did not always rely on the SID and PAC in Kerberos tickets (CVE-2020-25719)

Tenable has extracted the preceding description block directly from the AlmaLinux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote SUSE Linux SUSE15 host has packages installed that are affected by multiple vulnerabilities as referenced in the openSUSE-SU-2021:3647-1 advisory.

  - An attacker can downgrade a negotiated SMB1 client connection and its capabitilities. Kerberos     authentication is only possible with the SMB2/3 protocol or SMB1 using the NT1 dialect and the extended     security (spnego) capability. Without mandatory SMB signing the protocol can be downgraded to an older     insecure dialect like CORE, COREPLUS/CORE+, LANMAN1 or LANMAN2. Even if SMB signing is required it's still     possible to downgrade to the NT1 dialect if extended security (spnego) is not negotiated. The attacker is     able to get the plaintext password sent over the wire even if Kerberos authentication was required. The     problem is only possible if all of the following options are explicitly set together: client NTLMv2 auth =     no client lanman auth = yes client plaintext auth = yes client min protocol = NT1 # or lower In currently     supported Samba versions all of the above options have different default values, so the problem is very     unlikely to happen. Samba 4.5 and older had an additional problem, even in the default configuration, as     they send ntlmv2, ntlm or lanman responses. Which means the attacker might be able to do offline attacks     in order to recover the plaintext password, lmhash or nthash values. Requiring Kerberos authentication for     SMB1/2/3 connections can be controlled by the '-k'/'--kerberos' or '-k yes'/'--kerberos=yes' command line     options of various tools like: smbclient, smbcquotas, smbcacls, net, rpcclient, samba-tool and others.
    Note that 4.15 deprecated '-k/--kerberos*' and introduced '--use-kerberos=required' command line option as     well as the smb.conf option client use kerberos = required. For libsmbclient based applications the     usage of Kerberos is controlled by the following function calls: smbc_setOptionUseKerberos(),     smbc_setOptionFallbackAfterKerberos() and smbc_setOptionNoAutoAnonymousLogin(). (CVE-2016-2124)

  - Windows Active Directory (AD) domains have by default a feature to allow users to create computer     accounts, controlled by ms-DS-MachineAccountQuota. In addition some (presumably trusted) users have the     right to create new users or computers in both Samba and Windows Active Directory Domains. These features     can be quite dangerous in the wrong hands, as the user who creates such accounts has broad privileges to     not just create them and set their passwords, but to rename them at a later time with the only contraint     being they may not match an existing samAccountName in AD. When Samba as an AD Domain member accepts a     Kerberos ticket, it must map the information found therein to a local UNIX user-id (uid). This is     currently done via the account name in the Active Directory generated Kerberos Privileged Attribute     Certificate (PAC), or the account name in the ticket (if there is no PAC). For example, Samba will attempt     to find a user DOMAIN\user before falling back to trying to find the user user. If the DOMAIN\user     lookup can be made to fail, then a privilege escalation is possible. The easiest example to illustrate     this is if an attacker creates an account named root (by renaming a MachineAccountQuota based machine     account), and asks for a login without a Kerberos PAC. Between obtaining the ticket and presenting it to a     server, the attacker renames the user account to a different name. Samba attempts to look up     DOMAIN\root, which fails (as this no longer exists) and then falls back to looking up user root, which     will map to the privileged UNIX uid of 0. This patch changes Samba to require a PAC (in all scenarios     related to active directory domains) and use the SID and account name values of the PAC, which means the     combination represents the same point in time. The processing is now similar to as with NTLM based logins.
    The SID is unique and non-repeating and so can't be confused with another user. Additionally, a new     parameter has been added min domain uid (default 1000), and no matter how we obtain the UNIX uid to use     in the process token (we may eventually read /etc/passwd or similar), by default no UNIX uid below this     value will be accepted. The patch also removes the fallback from 'DOMAIN\user' to just 'user', as it     dangerous and not needed when nss_winbind is used (even when 'winbind use default domain = yes' is set).
    However there are setups which are joined to an active directory domain just for authentication, but the     authorization is handled without nss_winbind by mapping the domain account to a local user provided by     nss_file, nss_ldap or something similar. NOTE: These setups won't work anymore without explicitly mapping     the users! For these setups administrators need to use the 'username map' or 'username map script' option     in order to map domain users explicitly to local users, e.g. user = DOMAIN\user Please consult 'man 5     smb.conf' for further details on 'username map' or 'username map script'. Also note that in the above     example '\' refers to the default value of the 'winbind separator' option. (CVE-2020-25717)

  - Samba as an Active Directory Domain Controller is able to support an RODC, which is meant to have minimal     privileges in a domain. However, in accepting a ticket from a Samba or Windows RODC, Samba was not     confirming that the RODC is authorized to print such a ticket, via the msDS-NeverRevealGroup and msDS-     RevealOnDemandGroup (typically Allowed RODC Replication Group and Denied RODC Replciation Group). This     would allow an RODC to print administrator tickets. (CVE-2020-25718)

  - Samba as an Active Directory Domain Controller is based on Kerberos, which provides name-based     authentication. These names are often then used for authorization. However Microsoft Windows and Active     Direcory is SID-based. SIDs in Windows, similar to UIDs in Linux/Unix (if managed well) are globally     unique and survive name changes. At the meeting of these two authorization schemes it is possible to     confuse a server into acting as one user when holding a ticket for another. A Kerberos ticket, once     issued, may be valid for some time, often 10 hours but potentially longer. In Active Directory, it may or     may not carry a PAC, holding the user's SIDs. A simple example of the problem is on Samba's LDAP server,     which would, unless gensec:require_pac = true was set, permit a fall back to using the name in the     Kerberos ticket alone. (All Samba AD services fall to the same issue in one way or another, LDAP is just a     good example). Delegated administrators with the right to create other user or machine accounts can abuse     the race between the time of ticket issue and the time of presentation (back to the AD DC) to impersonate     a different account, including a highly privileged account. This could allow total domain compromise.
    (CVE-2020-25719)

  - In order to avoid issues like CVE-2020-25717 AD Kerberos accepting services need access to unique, and     ideally long-term stable identifiers of a user to perform authorization. The AD PAC provides this, but the     most useful information is kept in a buffer which is NDR encoded, which means that so far in Free Software     only Samba and applications which use Samba components under the hood like FreeIPA and SSSD decode PAC.
    Recognising that the issues seen in Samba are not unique, Samba now provides an extension to UPN_DNS_INFO,     a component of the AD PAC, in a way that can be parsed using basic pointer handling. From this, future     non-Samba based Kerberised applications can easily obtain the user's SID, in the same packing as objectSID     in LDAP, confident that the ticket represents a specific user, not matter subsequent renames. This will     allow such non-Samba applications to avoid confusing one Kerberos user for another, even if they have the     same string name (due to the gap between time of ticket printing by the KDC and time of ticket     acceptance). The protocol deployment weakness, as demonstrated with the CVE-2020-25717 in Samba when     deployed in Active Directory, leaves most Linux and UNIX applications only to rely on the client name     from the Kerberos ticket. When the client name as seen by the KDC is under an attacker control across     multiple Kerberos requests, such applications need an additional information to correlate the client name     across those requests. Directories where only full administrators can create users are not the concern,     the concern is where that user/computer creation right is delegated in some way, explicitly or via ms-DS-     MachineAccountQuota. (CVE-2020-25721)

  - Samba as an Active Directory Domain Controller has to take care to protect a number of sensitive     attributes, and to follow a security model from Active Directory that relies totally on the intersection     of NT security descriptors and the underlying X.500 Directory Access Protocol (as then expressed in LDAP)     schema constraints for security. Some attributes in Samba AD are sensitive, they apply to one object but     protect others. Users who can set msDS-AllowedToDelegateTo can become any user in the domain on the server     pointed at by this list. Likewise in a domain mixed with Microsoft Windows, Samba's lack of protection of     sidHistory would be a similar issue. This would be limited to users with the right to create users or     modify them (typically those who created them), however, due to other flaws, all users are able to create     new user objects. Finally, Samba did not enforce userPrincipalName and servicePrincipalName uniqueness,     nor did it correctly implement the validated SPN feature allowing machine accounts to safely set their     own SPN (the checks were easily bypassed and additionally should have been restricted to     objectClass=computer). Samba has implemented this feature, which avoids a denial of service (UPNs) or     service impersonation (SPNs) between users privileged to add users to the domian (but see the above     point). This release adds a feature similar in goal but broader in implementation than that found in the     Windows 2012 Forest Functional level. (CVE-2020-25722)

  - Samba implements DCE/RPC, and in most cases it is provided over and protected by the underlying SMB     transport, with protections like 'SMB signing'. However there are other cases where large DCE/RPC request     payloads are exchanged and fragmented into several pieces. If this happens over untrusted transports (e.g.
    directly over TCP/IP or anonymous SMB) clients will typically protect by an explicit authentication at the     DCE/RPC layer, e.g. with GSSAPI/Kerberos/NTLMSSP or Netlogon Secure Channel. Because the checks on the     fragment protection were not done between the policy controls on the header and the subsequent fragments,     an attacker could replace subsequent fragments in requests with their own data, which might be able to     alter the server behaviour. DCE/RPC is a core component of all Samba servers, but we are most concerned     about Samba as a Domain Controller, given the role as a centrally trusted service. As active directory     domain controller this issue affects Samba versions greater or equal to 4.10.0. As NT4 classic domain     controller, domain member or standalone server this issue affects Samba versions greater or equal to     4.13.0. (CVE-2021-23192)

  - In DCE/RPC it is possible to share the handles (cookies for resource state) between multiple connections     via a mechanism called 'association groups'. These handles can reference connections to our sam.ldb     database. However while the database was correctly shared, the user credentials state was only pointed at,     and when one connection within that association group ended, the database would be left pointing at an     invalid 'struct session_info'. The most likely outcome here is a crash, but it is possible that the use-     after-free could instead allow different user state to be pointed at and this might allow more privileged     access. (CVE-2021-3738)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The remote Ubuntu 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-5142-1 advisory.

    Stefan Metzmacher discovered that Samba incorrectly handled SMB1 client connections. A remote attacker     could possibly use this issue to downgrade connections to plaintext authentication. (CVE-2016-2124)

    Andrew Bartlett discovered that Samba incorrectly mapping domain users to local users. An authenticated     attacker could possibly use this issue to become root on domain members. (CVE-2020-25717)

    Andrew Bartlett discovered that Samba did not correctly sandbox Kerberos tickets issues by an RODC. An     RODC could print administrator tickets, contrary to expectations. (CVE-2020-25718)

    Andrew Bartlett discovered that Samba incorrectly handled Kerberos tickets. Delegated administrators could     possibly use this issue to impersonate accounts, leading to total domain compromise. (CVE-2020-25719)

    Andrew Bartlett discovered that Samba did not provide stable AD identifiers to Kerberos acceptors.
    (CVE-2020-25721)

    Andrew Bartlett discovered that Samba did not properly check sensitive attributes. An authenticated     attacker could possibly use this issue to escalate privileges. (CVE-2020-25722)

    Stefan Metzmacher discovered that Samba incorrectly handled certain large DCE/RPC requests. A remote     attacker could possibly use this issue to bypass signature requirements. (CVE-2021-23192)

    William Ross discovered that Samba incorrectly handled memory. A remote attacker could use this issue to     cause Samba to crash, resulting in a denial of service, or possibly escalate privileges. (CVE-2021-3738)

    Joseph Sutton discovered that Samba incorrectly handled certain TGS requests. An authenticated attacker     could possibly use this issue to cause Samba to crash, resulting in a denial of service. (CVE-2021-3671)

    The fix for CVE-2020-25717 results in possible behaviour changes that could affect certain environments.
    Please see the upstream advisory for more information:

    https://www.samba.org/samba/security/CVE-2020-25717.html

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

ID	Name	Product	Family	Published	Updated	Severity
156107	RHEL 8 : idm:DL1 (RHSA-2021:5142)	Nessus	Red Hat Local Security Checks	12/15/2021	11/7/2024	high
156120	Oracle Linux 8 : idm:DL1 (ELSA-2021-5142)	Nessus	Oracle Linux Local Security Checks	12/16/2021	11/1/2024	high
156133	RHEL 7 : ipa (RHSA-2021:5195)	Nessus	Red Hat Local Security Checks	12/17/2021	11/7/2024	high
156176	Scientific Linux Security Update : ipa on SL7.x x86_64 (2021:5195)	Nessus	Scientific Linux Local Security Checks	12/18/2021	3/1/2022	high
156242	CentOS 7 : ipa (RHSA-2021:5195)	Nessus	CentOS Local Security Checks	12/21/2021	10/9/2024	high
294106	MiracleLinux 8 : idm:DL1 (AXSA:2022-3004:01)	Nessus	Miracle Linux Local Security Checks	1/20/2026	1/20/2026	high
158375	EulerOS 2.0 SP10 : samba (EulerOS-SA-2022-1258)	Nessus	Huawei Local Security Checks	2/25/2022	11/8/2022	high
158550	EulerOS 2.0 SP9 : samba (EulerOS-SA-2022-1295)	Nessus	Huawei Local Security Checks	3/2/2022	11/8/2022	high
158848	AlmaLinux 8 : idm:DL1 (ALSA-2021:5142)	Nessus	Alma Linux Local Security Checks	3/11/2022	1/13/2025	high
155177	openSUSE 15 Security Update : samba and ldb (openSUSE-SU-2021:3647-1)	Nessus	SuSE Local Security Checks	11/11/2021	11/28/2022	high
155297	Ubuntu 20.04 LTS : Samba vulnerabilities (USN-5142-1)	Nessus	Ubuntu Local Security Checks	11/12/2021	8/28/2024	high

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