Debian Security Advisory 5525-1

Gentoo Linux Security Advisory 202402-28 - Multiple vulnerabilities have been discovered in Samba, the worst of which can lead to remote code execution. Versions greater than or equal to 4.18.9 are affected.

Red Hat Security Advisory 2023-6209-01 - An update for samba is now available for Red Hat Enterprise Linux 9.0 Extended Update Support. Issues addressed include a denial of service vulnerability.

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 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.

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.

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 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.

Ubuntu Security Notice 6425-3 - USN-6425-1 fixed vulnerabilities in Samba. This update provides the corresponding updates for Ubuntu 23.10. Sri Nagasubramanian discovered that the Samba acl_xattr VFS module incorrectly handled read-only files. When Samba is configured to ignore system ACLs, a remote attacker could possibly use this issue to truncate read-only files. Andrew Bartlett discovered that Samba incorrectly handled the DirSync control. A remote attacker with an RODC DC account could possibly use this issue to obtain all domain secrets. Andrew Bartlett discovered that Samba incorrectly handled the rpcecho development server. A remote attacker could possibly use this issue to cause Samba to stop responding, resulting in a denial of service. Kirin van der Veer discovered that Samba incorrectly handled certain RPC service listeners. A remote attacker could possibly use this issue to cause Samba to start multiple incompatible RPC listeners, resulting in a denial of service. This iss...

Ubuntu Security Notice 6425-2 - USN-6425-1 fixed vulnerabilities in Samba. Due to a build issue on Ubuntu 20.04 LTS, the update introduced regressions in macro handling and possibly other functionality. This update fixes the problem. Sri Nagasubramanian discovered that the Samba acl_xattr VFS module incorrectly handled read-only files. When Samba is configured to ignore system ACLs, a remote attacker could possibly use this issue to truncate read-only files. Andrew Bartlett discovered that Samba incorrectly handled the DirSync control. A remote attacker with an RODC DC account could possibly use this issue to obtain all domain secrets. Andrew Bartlett discovered that Samba incorrectly handled the rpcecho development server. A remote attacker could possibly use this issue to cause Samba to stop responding, resulting in a denial of service. Kirin van der Veer discovered that Samba incorrectly handled certain RPC service listeners. A remote attacker could possibly use this issue to cause ...