Samba : Security Vulnerabilities, CVEs, CVSS score >= 6

A flaw was found in Samba. It is susceptible to a vulnerability where multiple incompatible RPC listeners can be initiated, causing disruptions in the AD DC service. When Samba's RPC server experiences a high load or unresponsiveness, servers intended for non-AD DC purposes (for example, NT4-emulation "classic DCs") can erroneously start and compete for the same unix domain sockets. This issue leads to partial query responses from the AD DC, causing issues such as "The procedure number is out of range" when using tools like Active Directory Users. This flaw allows an attacker to disrupt AD DC services.

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 "dcesrv_echo_TestSleep()" 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.

An infinite loop vulnerability was found in Samba's mdssvc RPC service for Spotlight. When parsing Spotlight mdssvc RPC packets sent by the client, the core unmarshalling function sl_unpack_loop() did not validate a field in the network packet that contains the count of elements in an array-like structure. By passing 0 as the count value, the attacked function will run in an endless loop consuming 100% CPU. This flaw allows an attacker to issue a malformed RPC request, triggering an infinite loop, resulting in a denial of service condition.

A heap-based Buffer Overflow flaw was discovered in Samba. It could allow a remote, authenticated attacker to exploit this vulnerability to cause a denial of service.

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 GET_CHANGES 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.

A vulnerability was discovered in Samba, where the flaw allows SMB clients to truncate files, even with read-only permissions when the Samba VFS module "acl_xattr" is configured with "acl_xattr:ignore system acls = yes". The SMB protocol allows opening files when the client requests read-only access but then implicitly truncates the opened file to 0 bytes if the client specifies a separate OVERWRITE create disposition request. The issue arises in configurations that bypass kernel file system permissions checks, relying solely on Samba's permissions.

A path traversal vulnerability was identified in Samba when processing client pipe names connecting to Unix domain sockets within a private directory. Samba typically uses this mechanism to connect SMB clients to remote procedure call (RPC) services like SAMR LSA or SPOOLSS, which Samba initiates on demand. However, due to inadequate sanitization of incoming client pipe names, allowing a client to send a pipe name containing Unix directory traversal characters (../). This could result in SMB clients connecting as root to Unix domain sockets outside the private directory. If an attacker or client managed to send a pipe name resolving to an external service using an existing Unix domain socket, it could potentially lead to unauthorized access to the service and consequential adverse events, including compromise or service crashes.

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.

Since the Windows Kerberos RC4-HMAC Elevation of Privilege Vulnerability was disclosed by Microsoft on Nov 8 2022 and per RFC8429 it is assumed that rc4-hmac is weak, Vulnerable Samba Active Directory DCs will issue rc4-hmac encrypted tickets despite the target server supporting better encryption (eg aes256-cts-hmac-sha1-96).

Heimdal before 7.7.1 allows remote attackers to execute arbitrary code because of an invalid free in the ASN.1 codec used by the Key Distribution Center (KDC).

PAC parsing in MIT Kerberos 5 (aka krb5) before 1.19.4 and 1.20.x before 1.20.1 has integer overflows that may lead to remote code execution (in KDC, kadmind, or a GSS or Kerberos application server) on 32-bit platforms (which have a resultant heap-based buffer overflow), and cause a denial of service on other platforms. This occurs in krb5_pac_parse in lib/krb5/krb/pac.c. Heimdal before 7.7.1 has "a similar bug."

Netlogon RPC Elevation of Privilege Vulnerability

Windows Kerberos Elevation of Privilege Vulnerability

Windows Kerberos RC4-HMAC Elevation of Privilege Vulnerability

A flaw was found in Samba. Samba AD users can cause the server to access uninitialized data with an LDAP add or modify the request, usually resulting in a segmentation fault.

A flaw was found in Samba. The KDC accepts kpasswd requests encrypted with any key known to it. By encrypting forged kpasswd requests with its own key, a user can change other users' passwords, enabling full domain takeover.

Samba does not validate the Validated-DNS-Host-Name right for the dNSHostName attribute which could permit unprivileged users to write it.

An issue was discovered in rsync before 3.2.5 that allows malicious remote servers to write arbitrary files inside the directories of connecting peers. The server chooses which files/directories are sent to the client. However, the rsync client performs insufficient validation of file names. A malicious rsync server (or Man-in-The-Middle attacker) can overwrite arbitrary files in the rsync client target directory and subdirectories (for example, overwrite the .ssh/authorized_keys file).

In cifs-utils through 6.14, a stack-based buffer overflow when parsing the mount.cifs ip= command-line argument could lead to local attackers gaining root privileges.

A vulnerability classified as problematic has been found in ppp. Affected is the function dumpppp of the file pppdump/pppdump.c of the component pppdump. The manipulation of the argument spkt.buf/rpkt.buf leads to improper validation of array index. The real existence of this vulnerability is still doubted at the moment. The name of the patch is a75fb7b198eed50d769c80c36629f38346882cbf. It is recommended to apply a patch to fix this issue. VDB-216198 is the identifier assigned to this vulnerability. NOTE: pppdump is not used in normal process of setting up a PPP connection, is not installed setuid-root, and is not invoked automatically in any scenario.

A symlink following vulnerability was found in Samba, where a user can create a symbolic link that will make 'smbd' escape the configured share path. This flaw allows a remote user with access to the exported part of the file system under a share via SMB1 unix extensions or NFS to create symlinks to files outside the 'smbd' configured share path and gain access to another restricted server's filesystem.

A heap-based buffer overflow vulnerability was found in Samba within the GSSAPI unwrap_des() and unwrap_des3() 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.

A flaw was found in Samba. The security vulnerability occurs when KDC and the kpasswd service share a single account and set of keys, allowing them to decrypt each other's tickets. A user who has been requested to change their password, can exploit this flaw to obtain and use tickets to other services.

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.

The Samba vfs_fruit module uses extended file attributes (EA, xattr) to provide "...enhanced compatibility with Apple SMB clients and interoperability with a Netatalk 3 AFP fileserver." Samba versions prior to 4.13.17, 4.14.12 and 4.15.5 with vfs_fruit configured allow out-of-bounds heap read and write via specially crafted extended file attributes. A remote attacker with write access to extended file attributes can execute arbitrary code with the privileges of smbd, typically root.