CVE-2021-3738

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.

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.

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.

Samba is a suite of programs for Linux and Unix to interoperate with Windows.

Security Fix(es):

A flaw was discovered in the way samba implements SMB1 authentication. Even if Kerberos authentication is required, an attacker can use this flaw to retrieve the clear text password sent over the wire.(CVE-2016-2124)

Several flaws were found in the way that samba AD DC implements storage data access and consistency checking. Attackers can use this flaw to cause damage to the entire domain.(CVE-2020-25722)

A use-after-free issue was found in the Samba AD DC RPC server, which may allow handles to point to different user states, leading to more privileged access.(CVE-2021-3738)

A flaw was found in the way that samba as an AD domain controller can support RODC. This will allow RODC to print administrator credentials.(CVE-2020-25718)

A flaw was discovered in the way that Samba, as an AD domain controller, implements Kerberos name-based authentication. If Samba AD DC does not strictly require Kerberos PAC and always uses the SID found in it, it may not be able to distinguish the user represented by the credential.(CVE-2020-25719)

The AD Kerberos acceptance service in Samba cannot perform authorization by accessing the user's unique and long-term stable identifier.(CVE-2020-25721)

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.

• SECURITY UPDATE: use after free in Samba AD DC RPC server
  • debian/patches/CVE-2021-3738-pre.patch: prepare service routines before fixing CVE-2021-3738
  • debian/patches/CVE-2021-3738.patch: avoids a crash caused by use-after-free in Samba AD DC RPC server
  • CVE-2021-3738.patch
• SECURITY UPDATE: integer overflow in PAC parsing
  • debian/patches/CVE-2022-42898.patch: catch overflows that result from adding PAC_INFO_BUFFER_SIZE
  • CVE-2022-42898

• SECURITY UPDATE: improper handling of association groups can lead to use- after-free vulnerability
  • debian/patches/CVE-2021-3738.patch: Fix routines for preparing service before handling CVE-2021-3738
  • debian/patches/CVE-2021-3738-1.patch: Fix DsBindAssocGroupAdmin to use admin credentials for DsBind
  • CVE-2021-3738

• SECURITY UPDATE: use after free in Samba AD DC RPC server
  • debian/patches/CVE-2021-3738-pre.patch: prepare service routines before fixing CVE-2021-3738
  • debian/patches/CVE-2021-3738.patch: avoids a crash caused by use-after-free in Samba AD DC RPC server
  • CVE-2021-3738.patch

Multiple security issues affecting ldb, samba and sssd. See references for details.

This update for samba and ldb fixes the following issues:

• CVE-2020-25718: Fixed that an RODC can issue (forge) administrator tickets to other servers (bsc#1192246).
• CVE-2021-3738: Fixed crash in dsdb stack (bsc#1192215).
• CVE-2016-2124: Fixed not to fallback to non spnego authentication if we require kerberos (bsc#1014440).
• CVE-2020-25717: Fixed privilege escalation inside an AD Domain where a user could become root on domain members (bsc#1192284).
• CVE-2020-25719: Fixed AD DC Username based races when no PAC is given (bsc#1192247).
• CVE-2020-25722: Fixed AD DC UPN vs samAccountName not checked (top-level bug for AD DC validation issues) (bsc#1192283).
• CVE-2021-23192: Fixed dcerpc requests to don't check all fragments against the first auth_state (bsc#1192214).
• CVE-2020-25721: Fixed fill in the new HAS_SAM_NAME_AND_SID values (bsc#1192505).

Samba was updated to 4.13.13

• rodc_rwdc test flaps;(bso#14868).
• Backport bronze bit fixes, tests, and selftest improvements; (bso#14881).
• Provide a fix for MS CVE-2020-17049 in Samba [SECURITY] 'Bronze bit' S4U2Proxy Constrained Delegation bypass in Samba with embedded Heimdal;(bso#14642).
• Python ldb.msg_diff() memory handling failure;(bso#14836).
• 'in' operator on ldb.Message is case sensitive;(bso#14845).
• Fix Samba support for UF_NO_AUTH_DATA_REQUIRED;(bso#14871).
• Allow special chars like '@' in samAccountName when generating the salt;(bso#14874).
• Fix transit path validation;(bso#12998).
• Prepare to operate with MIT krb5 >= 1.20;(bso#14870).
• rpcclient NetFileEnum and net rpc file both cause lock order violation: brlock.tdb, share_entries.tdb;(bso#14645).
• Python ldb.msg_diff() memory handling failure;(bso#14836).
• Release LDB 2.3.1 for Samba 4.14.9;(bso#14848).

Samba was updated to 4.13.12:

• Address a signifcant performance regression in database access in the AD DC since Samba 4.12;(bso#14806).
• Fix performance regression in lsa_LookupSids3/LookupNames4 since Samba 4.9 by using an explicit database handle cache; (bso#14807).
• An unuthenticated user can crash the AD DC KDC by omitting the server name in a TGS-REQ;(bso#14817).
• Address flapping samba_tool_drs_showrepl test;(bso#14818).
• Address flapping dsdb_schema_attributes test;(bso#14819).
• An unuthenticated user can crash the AD DC KDC by omitting the server name in a TGS-REQ;(bso#14817).
• Fix CTDB flag/status update race conditions(bso#14784).

Samba was updated to 4.13.11:

• smbd: panic on force-close share during offload write; (bso#14769).
• Fix returned attributes on fake quota file handle and avoid hitting the VFS;(bso#14731).
• smbd: 'deadtime' parameter doesn't work anymore;(bso#14783).
• net conf list crashes when run as normal user;(bso#14787).
• Work around special SMB2 READ response behavior of NetApp Ontap 7.3.7;(bso#14607).
• Start the SMB encryption as soon as possible;(bso#14793).
• Winbind should not start if the socket path for the privileged pipe is too long;(bso#14792).

ldb was updated to 2.2.2:

• CVE-2020-25718: samba: An RODC can issue (forge) administrator tickets to other servers; (bsc#1192246); (bso#14558)
• CVE-2021-3738: samba: crash in dsdb stack; (bsc#1192215);(bso#14848)

Release ldb 2.2.2

• Corrected python behaviour for 'in' for LDAP attributes contained as part of ldb.Message;(bso#14845).
• Fix memory handling in ldb.msg_diff Corrected python docstrings;(bso#14836)
• Backport bronze bit fixes, tests, and selftest improvements; (bso#14881).

These are all security issues fixed in the ctdb-4.15.2+git.193.a4d6307f1fd-1.1 package on the GA media of openSUSE Tumbleweed.

This update for samba and ldb fixes the following issues:

• CVE-2020-25718: Fixed that an RODC can issue (forge) administrator tickets to other servers (bsc#1192246).
• CVE-2021-3738: Fixed crash in dsdb stack (bsc#1192215).
• CVE-2016-2124: Fixed not to fallback to non spnego authentication if we require kerberos (bsc#1014440).
• CVE-2020-25717: Fixed privilege escalation inside an AD Domain where a user could become root on domain members (bsc#1192284).
• CVE-2020-25719: Fixed AD DC Username based races when no PAC is given (bsc#1192247).
• CVE-2020-25722: Fixed AD DC UPN vs samAccountName not checked (top-level bug for AD DC validation issues) (bsc#1192283).
• CVE-2021-23192: Fixed dcerpc requests to don't check all fragments against the first auth_state (bsc#1192214).
• CVE-2020-25721: Fixed fill in the new HAS_SAM_NAME_AND_SID values (bsc#1192505).

Samba was updated to 4.13.13

• rodc_rwdc test flaps;(bso#14868).
• Backport bronze bit fixes, tests, and selftest improvements; (bso#14881).
• Provide a fix for MS CVE-2020-17049 in Samba [SECURITY] 'Bronze bit' S4U2Proxy Constrained Delegation bypass in Samba with embedded Heimdal;(bso#14642).
• Python ldb.msg_diff() memory handling failure;(bso#14836).
• 'in' operator on ldb.Message is case sensitive;(bso#14845).
• Fix Samba support for UF_NO_AUTH_DATA_REQUIRED;(bso#14871).
• Allow special chars like '@' in samAccountName when generating the salt;(bso#14874).
• Fix transit path validation;(bso#12998).
• Prepare to operate with MIT krb5 >= 1.20;(bso#14870).
• rpcclient NetFileEnum and net rpc file both cause lock order violation: brlock.tdb, share_entries.tdb;(bso#14645).
• Python ldb.msg_diff() memory handling failure;(bso#14836).
• Release LDB 2.3.1 for Samba 4.14.9;(bso#14848).

Samba was updated to 4.13.12:

• Address a signifcant performance regression in database access in the AD DC since Samba 4.12;(bso#14806).
• Fix performance regression in lsa_LookupSids3/LookupNames4 since Samba 4.9 by using an explicit database handle cache; (bso#14807).
• An unuthenticated user can crash the AD DC KDC by omitting the server name in a TGS-REQ;(bso#14817).
• Address flapping samba_tool_drs_showrepl test;(bso#14818).
• Address flapping dsdb_schema_attributes test;(bso#14819).
• An unuthenticated user can crash the AD DC KDC by omitting the server name in a TGS-REQ;(bso#14817).
• Fix CTDB flag/status update race conditions(bso#14784).

Samba was updated to 4.13.11:

• smbd: panic on force-close share during offload write; (bso#14769).
• Fix returned attributes on fake quota file handle and avoid hitting the VFS;(bso#14731).
• smbd: 'deadtime' parameter doesn't work anymore;(bso#14783).
• net conf list crashes when run as normal user;(bso#14787).
• Work around special SMB2 READ response behavior of NetApp Ontap 7.3.7;(bso#14607).
• Start the SMB encryption as soon as possible;(bso#14793).
• Winbind should not start if the socket path for the privileged pipe is too long;(bso#14792).

ldb was updated to 2.2.2:

• CVE-2020-25718: samba: An RODC can issue (forge) administrator tickets to other servers; (bsc#1192246); (bso#14558)
• CVE-2021-3738: samba: crash in dsdb stack; (bsc#1192215);(bso#14848)

Release ldb 2.2.2

• Corrected python behaviour for 'in' for LDAP attributes contained as part of ldb.Message;(bso#14845).
• Fix memory handling in ldb.msg_diff Corrected python docstrings;(bso#14836)
• Backport bronze bit fixes, tests, and selftest improvements; (bso#14881).

This update for ldb, samba fixes the following issues:

Changes in ldb:

• CVE-2020-25718: An RODC can issue (forge) administrator tickets to other servers; (bsc#1192246)
• CVE-2021-3738: Fixed a crash in dsdb stack (bsc#1192215)

Release ldb 2.2.2

• Corrected python behaviour for 'in' for LDAP attributes contained as part of ldb.Message
• Fix memory handling in ldb.msg_diff
• Backport bronze bit fixes, tests, and selftest improvements.

Changes in samba:

• CVE-2021-44142: Fixed an Out-of-Bound Read/Write on Samba vfs_fruit module; (bsc#1194859)

• The username map [script] advice from CVE-2020-25717 advisory note has undesired side effects for the local nt token. Fallback to a SID/UID based mapping if the name based lookup fails; (bsc#1192849); (bso#14901).

• Fix regression introduced by CVE-2020-25717 patches, winbindd does not start when 'allow trusted domains' is off; (bso#14899);

• CVE-2020-25717: Fixed that a user on the domain can become root on domain members; (bsc#1192284); (bso#14556).

• CVE-2020-25721: auth: Fill in the new HAS_SAM_NAME_AND_SID values; (bsc#1192505); (bso#14564).

• CVE-2020-25718: An RODC can issue (forge) administrator tickets to other servers; (bsc#1192246);(bso#14558).

• CVE-2020-25719: Fixed AD DC Username based races when no PAC is given;(bsc#1192247);(bso#14561).

• CVE-2020-25722: Fixed that AD DC UPN vs samAccountName not checked (top-level bug for AD DC validation issues);(bsc#1192283); (bso#14564).

• CVE-2021-3738: Fixed a crash in dsdb stack;(bsc#1192215); (bso#14468).

• CVE-2021-23192: Fixed that dcerpc requests don't check all fragments against the first auth_state;(bsc#1192214);(bso#14875).

• CVE-2016-2124: don't fallback to non spnego authentication if we require kerberos; (bsc#1014440); (bso#12444).

Update to 4.13.13

• rodc_rwdc test flaps;(bso#14868).
• Backport bronze bit fixes, tests, and selftest improvements; (bso#14881).
• Provide a fix for MS CVE-2020-17049 in Samba [SECURITY] 'Bronze bit' S4U2Proxy Constrained Delegation bypass in Samba with embedded Heimdal;(bso#14642).
• Python ldb.msg_diff() memory handling failure;(bso#14836).
• 'in' operator on ldb.Message is case sensitive;(bso#14845).
• Fix Samba support for UF_NO_AUTH_DATA_REQUIRED;(bso#14871).
• Allow special chars like '@' in samAccountName when generating the salt;(bso#14874).
• Fix transit path validation;(bso#12998).
• Prepare to operate with MIT krb5 >= 1.20;(bso#14870).
• rpcclient NetFileEnum and net rpc file both cause lock order violation: brlock.tdb, share_entries.tdb;(bso#14645).
• Python ldb.msg_diff() memory handling failure;(bso#14836).
• Release LDB 2.3.1 for Samba 4.14.9;(bso#14848).

• Update to 4.13.12

  • Address a signifcant performance regression in database access in the AD DC since Samba 4.12;(bso#14806).
  • Fix performance regression in lsa_LookupSids3/LookupNames4 since Samba 4.9 by using an explicit database handle cache; (bso#14807).
  • An unuthenticated user can crash the AD DC KDC by omitting the server name in a TGS-REQ;(bso#14817).
  • Address flapping samba_tool_drs_showrepl test;(bso#14818).
  • Address flapping dsdb_schema_attributes test;(bso#14819).
  • An unuthenticated user can crash the AD DC KDC by omitting the server name in a TGS-REQ;(bso#14817).
  • Fix CTDB flag/status update race conditions(bso#14784).

• Update to 4.13.11

  • smbd: panic on force-close share during offload write; (bso#14769).
  • Fix returned attributes on fake quota file handle and avoid hitting the VFS;(bso#14731).
  • smbd: 'deadtime' parameter doesn't work anymore;(bso#14783).
  • net conf list crashes when run as normal user;(bso#14787).
  • Work around special SMB2 READ response behavior of NetApp Ontap 7.3.7;(bso#14607).
  • Start the SMB encryption as soon as possible;(bso#14793).
  • Winbind should not start if the socket path for the…

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 possibly use this issue to become root on domain members. (CVE-2020-25717)

Andrew Bartlett discovered that Samba did not correctly sandbox Kerberos tickets issues by an RODC. An RODC could print administrator tickets, contrary to expectations. (CVE-2020-25718)

Andrew Bartlett discovered that Samba incorrectly handled Kerberos tickets. Delegated administrators could possibly use this issue to impersonate accounts, leading to total domain compromise. (CVE-2020-25719)

Andrew Bartlett discovered that Samba did not provide stable AD identifiers to Kerberos acceptors. (CVE-2020-25721)

Andrew Bartlett discovered that Samba did not properly check sensitive attributes. An authenticated attacker could possibly use this issue to escalate privileges. (CVE-2020-25722)

Stefan Metzmacher discovered that Samba incorrectly handled certain large DCE/RPC requests. A remote attacker could possibly use this issue to bypass signature requirements. (CVE-2021-23192)

William Ross discovered that Samba incorrectly handled memory. A remote attacker could use this issue to cause Samba to crash, resulting in a denial of service, or possibly escalate privileges. (CVE-2021-3738)

Joseph Sutton discovered that Samba incorrectly handled certain TGS requests. An authenticated attacker could possibly use this issue to cause Samba to crash, resulting in a denial of service. (CVE-2021-3671)

The fix for CVE-2020-25717 results in possible behaviour changes that could affect certain environments. Please see the upstream advisory for more information:

https://www.samba.org/samba/security/CVE-2020-25717.html