A flaw was found in Samba. Some SMB1 write requests were not correctly range-checked to ensure the client had sent enough data to fulfill the write, allowing server memory contents to be written into the file (or printer) instead of client-supplied data. The client cannot control the area of the server memory written to the file (or printer).
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.
Kerberos acceptors need easy access to stable AD identifiers (eg objectSid). Samba as an AD DC now provides a way for Linux applications to obtain a reliable SID (and samAccountName) in issued tickets.
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.
A flaw was found in the way samba implemented DCE/RPC. If a client to a Samba server sent a very large DCE/RPC request, and chose to fragment it, an attacker could replace later fragments with their own data, bypassing the signature requirements.
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.
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.
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.
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.
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.
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.
All versions of Samba prior to 4.13.16 are vulnerable to a malicious client using an SMB1 or NFS race to allow a directory to be created in an area of the server file system not exported under the share definition. Note that SMB1 has to be enabled, or the share also available via NFS in order for this attack to succeed.
USN-5142-1 fixed vulnerabilities in Samba. Some of the upstream changes
introduced a regression in Kerberos authentication in certain environments.
Please see the following upstream bug for more information:
https://bugzilla.samba.org/show_bug.cgi?id=14922
This update fixes the problem.
Original advisory details:
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 po
USN-5142-1 fixed vulnerabilities in Samba. Some of the upstream changes
introduced regressions in name mapping and backups.
Please see the following upstream bugs for more information:
https://bugzilla.samba.org/show_bug.cgi?id=14901
https://bugzilla.samba.org/show_bug.cgi?id=14918
This update fixes the problem.
Original advisory details:
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 authe
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.
A flaw was found in samba. The Samba smbd file server must map Windows group identities (SIDs) into unix group ids (gids). The code that performs this had a flaw that could allow it to read data beyond the end of the array in the case where a negative cache entry had been added to the mapping cache. This could cause the calling code to return those values into the process token that stores the group membership for a user. The highest threat from this vulnerability is to data confidentiality and integrity.
A flaw was found in the way samba handled file and directory permissions. An authenticated user could use this flaw to gain access to certain file and directory information which otherwise would be unavailable to the attacker.
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 null pointer dereference flaw was found in samba's Winbind service in versions before 4.11.15, before 4.12.9 and before 4.13.1. A local user could use this flaw to crash the winbind service causing denial of service.