MGASA-2023-0340 - Updated samba packages fix security vulnerabilities

Publication date: 05 Dec 2023
URL: https://advisories.mageia.org/MGASA-2023-0340.html
Type: security
Affected Mageia releases: 9
CVE: CVE-2023-3961,
     CVE-2023-4091,
     CVE-2023-42669

This update fixes the security issues below.

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.
(CVE-2023-3961)

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. (CVE-2023-4091)

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
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. (CVE-2023-42669)

Apart from the new version, a Recommends for cifs-client was added in
samba-client for https://bugs.mageia.org/show_bug.cgi?id=28606

References:
- https://bugs.mageia.org/show_bug.cgi?id=32560
- https://bugs.mageia.org/show_bug.cgi?id=28606
- https://lwn.net/Articles/952257/
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-3961
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-4091
- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-42669

SRPMS:
- 9/core/samba-4.17.12-1.mga9

Mageia 2023-0340: samba security update

This update fixes the security issues below

Summary

This update fixes the security issues below.
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. (CVE-2023-3961)
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. (CVE-2023-4091)
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 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. (CVE-2023-42669)
Apart from the new version, a Recommends for cifs-client was added in samba-client for https://bugs.mageia.org/show_bug.cgi?id=28606

References

- https://bugs.mageia.org/show_bug.cgi?id=32560

- https://bugs.mageia.org/show_bug.cgi?id=28606

- https://lwn.net/Articles/952257/

- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-3961

- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-4091

- https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-42669

Resolution

MGASA-2023-0340 - Updated samba packages fix security vulnerabilities

SRPMS

- 9/core/samba-4.17.12-1.mga9

Severity
Publication date: 05 Dec 2023
URL: https://advisories.mageia.org/MGASA-2023-0340.html
Type: security
CVE: CVE-2023-3961, CVE-2023-4091, CVE-2023-42669

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