As per upstream samba advisory:

All versions of Samba from 3.5.0 to 4.2.0rc4 are vulnerable to an unexpected code execution vulnerability in the smbd file server daemon.

A malicious client could send packets that may set up the stack in such a way that the freeing of memory in a subsequent anonymous netlogon packet could allow execution of arbitrary code. This code would execute with root privileges.

As per upstream advisory:

All versions of Samba from 4.0.0 onwards are vulnerable to a use after free vulnerability, where a malicious SMB1 request can be used to control the contents of heap memory via a deallocated heap pointer. It is possible this may be used to compromise the SMB server.

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.

As per upstream report:

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 sessioninfo'.

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.

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.

As per upstream advisory:

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.

As per samba upstream advisory:

The Samba AD DC includes checks when adding service principals names (SPNs) to an account to ensure that SPNs do not alias with those already in the database. Some of these checks are able to be bypassed if an account modification re-adds an SPN that was previously present on that account, such as one added when a computer is joined to a domain.

An attacker who has the ability to write to an account can exploit this to perform a denial-of-service attack by adding an SPN that matches an existing service. Additionally, an attacker who can intercept traffic can impersonate existing services, resulting in a loss of confidentiality and integrity.

A flaw was found in samba versions 4.0.0 to 4.5.2. The Samba routine ndrpulldnspname contains an integer wrap problem, leading to an attacker-controlled memory overwrite. ndrpulldnspname parses data from the Samba Active Directory ldb database. Any user who can write to the dnsRecord attribute over LDAP can trigger this memory corruption. By default, all authenticated LDAP users can write to the dnsRecord attribute on new DNS objects. This makes the defect a remote privilege escalation.

Samba 4.0.x before 4.0.24, 4.1.x before 4.1.16, and 4.2.x before 4.2rc4, when an Active Directory Domain Controller (AD DC) is configured, allows remote authenticated users to set the LDB userAccountControl UFSERVERTRUSTACCOUNT bit, and consequently gain privileges, by leveraging delegation of authority for user-account or computer-account creation.

Heap-based buffer overflow in the dcerpcreadncacnpacketdone function in librpc/rpc/dcerpcutil.c in winbindd in Samba 3.x before 3.6.22, 4.0.x before 4.0.13, and 4.1.x before 4.1.3 allows remote AD domain controllers to execute arbitrary code via an invalid fragment length in a DCE-RPC packet.

Heimdal before 7.4 allows remote attackers to impersonate services with Orpheus' Lyre attacks because it obtains service-principal names in a way that violates the Kerberos 5 protocol specification. In krb5extractticket() the KDC-REP service name must be obtained from the encrypted version stored in 'encpart' instead of the unencrypted version stored in 'ticket'. Use of the unencrypted version provides an opportunity for successful server impersonation and other attacks. NOTE: this CVE is only for Heimdal and other products that embed Heimdal code; it does not apply to other instances in which this part of the Kerberos 5 protocol specification is violated.

As reported in the upstream advisory and bugzilla [1]:

All current versions of Samba 4.x.x are vulnerable to a remote code execution vulnerability in the nmbd NetBIOS name services daemon.

A malicious browser can send packets that may overwrite the heap of the target nmbd NetBIOS name services daemon. It may be possible to use this to generate a remote code execution vulnerability as the superuser (root).

Patches are available for 4.1.x [2] and 4.0.x [3].

[1] https://bugzilla.samba.org/showbug.cgi?id=10735 [2] https://git.samba.org/?p=samba.git;a=commitdiff;h=e6a848630da3ba958c442438ea131c99fa088605 [3] https://git.samba.org/?p=samba.git;a=commitdiff;h=fb1d325d96dfe9bc2e9c4ec46ad4c55e8f18f4a2

External References:

https://www.samba.org/samba/security/CVE-2014-3560

Statement:

This issue did not affect the versions of samba or samba3x as shipped with Red Hat Enterprise Linux 5, and the versions of samba as shipped with Red Hat Enterprise Linux 6, as it only affected Samba 4.0.0 and higher.

The fix in 4.6.16, 4.7.9, 4.8.4 and 4.9.7 for CVE-2018-10919 Confidential attribute disclosure vi LDAP filters was insufficient and an attacker may be able to obtain confidential BitLocker recovery keys from a Samba AD DC.

A design flaw was found in Samba's DirSync control implementation, which exposes passwords and secrets in Active Directory to privileged users and Read-Only Domain Controllers (RODCs). This flaw allows RODCs and users possessing the GETCHANGES right to access all attributes, including sensitive secrets and passwords. Even in a default setup, RODC DC accounts, which should only replicate some passwords, can gain access to all domain secrets, including the vital krbtgt, effectively eliminating the RODC / DC distinction. Furthermore, the vulnerability fails to account for error conditions (fail open), like out-of-memory situations, potentially granting access to secret attributes, even under low-privileged attacker influence.

As per samba upstream advisory:

Samba, operating as an AD DC, is sometimes operated in a domain with a mix of Samba and Windows Active Directory Domain Controllers.

All versions of Samba from 4.0.0 to 4.3.2 inclusive, when deployed as an AD DC in the same domain with Windows DCs, could be used to override the protection against the MS15-096 / CVE-2015-2535 security issue in Windows.

Prior to MS16-096 it was possible to bypass the quota of machine accounts a non-administrative user could create. Pure Samba domains are not impacted, as Samba does not implement the SeMachineAccountPrivilege functionality to allow non-administrator users to create new computer objects.

The following mitigation was suggested by upstream:

Only users with SeMachineAccountPrivilege can exploit this issue in Windows, removing this privilege from "Authenticated Users" can provide a mitigation.

It was reported that when adding an LDB DN to the database, that if a \00 (null byte) is used, remote memory can be read due to a combination of tallocstrdup() and a length assignment.

Upstream bug:

https://bugzilla.samba.org/showbug.cgi?id=11599

A denial-of-service vulnerability for the AD-DC due to insuffiecient checking on asn1 memory allocation was reported.

Upstream bug:

https://bugzilla.samba.org/showbug.cgi?id=9187

A flaw was found in Samba's libldb. Multiple, consecutive leading spaces in an LDAP attribute can lead to an out-of-bounds memory write, leading to a crash of the LDAP server process handling the request. The highest threat from this vulnerability is to system availability.

A flaw was found in samba. Spaces used in a string around a domain name (DN), while supposed to be ignored, can cause invalid DN strings with spaces to instead write a zero-byte into out-of-bounds memory, resulting in a crash. The highest threat from this vulnerability is to system availability.

A flaw was found when using samba as an Active Directory Domain Controller. Due to the way samba handles certain requests as an Active Directory Domain Controller LDAP server, an unauthorized user can cause a stack overflow leading to a denial of service. The highest threat from this vulnerability is to system availability. This issue affects all samba versions before 4.10.15, before 4.11.8 and before 4.12.2.

libcli/smb/smbXclibase.c in Samba 4.x before 4.2.14, 4.3.x before 4.3.11, and 4.4.x before 4.4.5 allows man-in-the-middle attackers to bypass a client-signing protection mechanism, and consequently spoof SMB2 and SMB3 servers, via the (1) SMB2SESSIONFLAGISGUEST or (2) SMB2SESSIONFLAGISNULL flag.

Samba 4.x before 4.2.11, 4.3.x before 4.3.8, and 4.4.x before 4.4.2 does not verify X.509 certificates from TLS servers, which allows man-in-the-middle attackers to spoof LDAPS and HTTPS servers and obtain sensitive information via a crafted certificate.

A vulnerability was found in Samba's "rpcecho" development server, a non-Windows RPC server used to test Samba's DCE/RPC stack elements. This vulnerability stems from an RPC function that can be blocked indefinitely. The issue arises because the "rpcecho" service operates with only one worker in the main RPC task, allowing calls to the "rpcecho" server to be blocked for a specified time, causing service disruptions. This disruption is triggered by a "sleep()" call in the "dcesrvechoTestSleep()" function under specific conditions. Authenticated users or attackers can exploit this vulnerability to make calls to the "rpcecho" server, requesting it to block for a specified duration, effectively disrupting most services and leading to a complete denial of service on the AD DC. The DoS affects all other services as "rpcecho" runs in the main RPC task.

As per upstream:

A remote, authenticated, attacker can cause the winbindd process to crash using a legitimate Kerberos ticket due to incorrect handling of the PAC checksum. A local service with access to the winbindd privileged pipe can cause winbindd to cache elevated access permissions.

For the remote attack, the memory overwrite kills the main winbindd process and an authenticated attacker can construct this situation by watching for password changes in Samba.

One specific trigger occurs when winbindd changes its machine account password and the client has still a valid Kerberos ticket (that was encrypted with the old password).

A flaw was found in samba's DNS server. An authenticated user could use this flaw to the RPC server to crash. This RPC server, which also serves protocols other than dnsserver, will be restarted after a short delay, but it is easy for an authenticated non administrative attacker to crash it again as soon as it returns. The Samba DNS server itself will continue to operate, but many RPC services will not.

A heap-based buffer overflow vulnerability was found in Samba within the GSSAPI unwrapdes() and unwrapdes3() routines of Heimdal. The DES and Triple-DES decryption routines in the Heimdal GSSAPI library allow a length-limited write buffer overflow on malloc() allocated memory when presented with a maliciously small packet. This flaw allows a remote user to send specially crafted malicious data to the application, possibly resulting in a denial of service (DoS) attack.

The NETLOGON service in Samba 3.x and 4.x before 4.2.11, 4.3.x before 4.3.8, and 4.4.x before 4.4.2, when a domain controller is configured, allows remote attackers to spoof the computer name of a secure channel's endpoint, and obtain sensitive session information, by running a crafted application and leveraging the ability to sniff network traffic, a related issue to CVE-2015-0005.

Samba 4.x before 4.0.4, when configured as an Active Directory domain controller, uses world-writable permissions on non-default CIFS shares, which allows remote authenticated users to read, modify, create, or delete arbitrary files via standard filesystem operations.

The Samba AD DC administration tool, when operating against a remote LDAP server, will by default send new or reset passwords over a signed-only connection.

The internal DNS server in Samba 4.x before 4.1.23, 4.2.x before 4.2.9, 4.3.x before 4.3.6, and 4.4.x before 4.4.0rc4, when an AD DC is configured, allows remote authenticated users to cause a denial of service (out-of-bounds read) or possibly obtain sensitive information from process memory by uploading a crafted DNS TXT record.