Memory leak in the Privilege Attribute Certificate (PAC) responder plugin (sssd_pac_plugin.so) in System Security Services Daemon (SSSD) 1.10 before 1.13.1 allows remote authenticated users to cause a denial of service (memory consumption) via a large number of logins that trigger parsing of PAC blobs during Kerberos authentication.

Security fix for CVE-2015-5292

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

It was found that SSSD's Privilege Attribute Certificate (PAC) responder plug-in would leak a small amount of memory on each authentication request. A remote attacker could potentially use this flaw to exhaust all available memory on the system by making repeated requests to a Kerberized daemon application configured to authenticate using the PAC responder plug-in.

It was found that SSSD's Privilege Attribute Certificate (PAC) responder plug-in would leak a small amount of memory on each authentication request. A remote attacker could potentially use this flaw to exhaust all available memory on the system by making repeated requests to a Kerberized daemon application configured to authenticate using the PAC responder plug-in. (CVE-2015-5292)

The sssd packages have been upgraded to upstream version 1.13.0, which provides a number of bug fixes and enhancements over the previous version.

  - SSSD smart card support * Cache authentication in SSSD *     SSSD supports overriding automatically discovered AD     site * SSSD can now deny SSH access to locked accounts *     SSSD enables UID and GID mapping on individual clients *     Background refresh of cached entries * Multi-step     prompting for one-time and long-term passwords * Caching     for initgroups operations

Bugs fixed :

  - When the SELinux user content on an IdM server was set     to an empty string, the SSSD SELinux evaluation utility     returned an error.

  - If the ldap_child process failed to initialize     credentials and exited with an error multiple times,     operations that create files in some cases started     failing due to an insufficient amount of i-nodes.

  - The SRV queries used a hard-coded TTL timeout, and     environments that wanted the SRV queries to be valid for     a certain time only were blocked. Now, SSSD parses the     TTL value out of the DNS packet.

  - Previously, initgroups operation took an excessive     amount of time. Now, logins and ID processing are faster     for setups with AD back end and disabled ID mapping.

  - When an IdM client with Scientific Linux 7.1 or later     was connecting to a server with Scientific Linux 7.0 or     earlier, authentication with an AD trusted domain caused     the sssd_be process to terminate unexpectedly.

  - If replication conflict entries appeared during HBAC     processing, the user was denied access. Now, the     replication conflict entries are skipped and users are     permitted access.

  - The array of SIDs no longer contains an uninitialized     value and SSSD no longer crashes.

  - SSSD supports GPOs from different domain controllers and     no longer crashes when processing GPOs from different     domain controllers.

  - SSSD could not refresh sudo rules that contained groups     with special characters, such as parentheses, in their     name.

  - The IPA names are not qualified on the client side if     the server already qualified them, and IdM group members     resolve even if default_domain_suffix is used on the     server side.

  - The internal cache cleanup task has been disabled by     default to improve performance of the sssd_be process.

  - Now, default_domain_suffix is not considered anymore for     autofs maps.

  - The user can set subdomain_inherit=ignore_group-members     to disable fetching group members for trusted domains.

  - The group resolution failed with an error message:
    'Error: 14 (Bad address)'. The binary GUID handling has     been fixed.

Enhancements added :

  - The description of default_domain_suffix has been     improved in the manual pages.

  - With the new '%0' template option, users on SSSD IdM     clients can now use home directories set on AD.

Updated sssd packages that fix one security issue, multiple bugs, and add various enhancements are now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

The System Security Services Daemon (SSSD) service provides a set of daemons to manage access to remote directories and authentication mechanisms.

It was found that SSSD's Privilege Attribute Certificate (PAC) responder plug-in would leak a small amount of memory on each authentication request. A remote attacker could potentially use this flaw to exhaust all available memory on the system by making repeated requests to a Kerberized daemon application configured to authenticate using the PAC responder plug-in. (CVE-2015-5292)

The sssd packages have been upgraded to upstream version 1.13.0, which provides a number of bug fixes and enhancements over the previous version. (BZ#1205554)

Several enhancements are described in the Red Hat Enterprise Linux 7.2 Release Notes, linked to in the References section :

* SSSD smart card support (BZ#854396)

* Cache authentication in SSSD (BZ#910187)

* SSSD supports overriding automatically discovered AD site (BZ#1163806)

* SSSD can now deny SSH access to locked accounts (BZ#1175760)

* SSSD enables UID and GID mapping on individual clients (BZ#1183747)

* Background refresh of cached entries (BZ#1199533)

* Multi-step prompting for one-time and long-term passwords (BZ#1200873)

* Caching for initgroups operations (BZ#1206575)

Bugs fixed :

* When the SELinux user content on an IdM server was set to an empty string, the SSSD SELinux evaluation utility returned an error.
(BZ#1192314)

* If the ldap_child process failed to initialize credentials and exited with an error multiple times, operations that create files in some cases started failing due to an insufficient amount of i-nodes.
(BZ#1198477)

* The SRV queries used a hard-coded TTL timeout, and environments that wanted the SRV queries to be valid for a certain time only were blocked. Now, SSSD parses the TTL value out of the DNS packet.
(BZ#1199541)

* Previously, initgroups operation took an excessive amount of time.
Now, logins and ID processing are faster for setups with AD back end and disabled ID mapping. (BZ#1201840)

* When an IdM client with Red Hat Enterprise Linux 7.1 or later was connecting to a server with Red Hat Enterprise Linux 7.0 or earlier, authentication with an AD trusted domain caused the sssd_be process to terminate unexpectedly. (BZ#1202170)

* If replication conflict entries appeared during HBAC processing, the user was denied access. Now, the replication conflict entries are skipped and users are permitted access. (BZ#1202245)

* The array of SIDs no longer contains an uninitialized value and SSSD no longer crashes. (BZ#1204203)

* SSSD supports GPOs from different domain controllers and no longer crashes when processing GPOs from different domain controllers.
(BZ#1205852)

* SSSD could not refresh sudo rules that contained groups with special characters, such as parentheses, in their name. (BZ#1208507)

* The IPA names are not qualified on the client side if the server already qualified them, and IdM group members resolve even if default_domain_suffix is used on the server side. (BZ#1211830)

* The internal cache cleanup task has been disabled by default to improve performance of the sssd_be process. (BZ#1212489)

* Now, default_domain_suffix is not considered anymore for autofs maps. (BZ#1216285)

* The user can set subdomain_inherit=ignore_group-members to disable fetching group members for trusted domains. (BZ#1217350)

* The group resolution failed with an error message: 'Error: 14 (Bad address)'. The binary GUID handling has been fixed. (BZ#1226119)

Enhancements added :

* The description of default_domain_suffix has been improved in the manual pages. (BZ#1185536)

* With the new '%0' template option, users on SSSD IdM clients can now use home directories set on AD. (BZ#1187103)

All sssd users are advised to upgrade to these updated packages, which correct these issues and add these enhancements.

From Red Hat Security Advisory 2015:2355 :

Updated sssd packages that fix one security issue, multiple bugs, and add various enhancements are now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

The System Security Services Daemon (SSSD) service provides a set of daemons to manage access to remote directories and authentication mechanisms.

It was found that SSSD's Privilege Attribute Certificate (PAC) responder plug-in would leak a small amount of memory on each authentication request. A remote attacker could potentially use this flaw to exhaust all available memory on the system by making repeated requests to a Kerberized daemon application configured to authenticate using the PAC responder plug-in. (CVE-2015-5292)

The sssd packages have been upgraded to upstream version 1.13.0, which provides a number of bug fixes and enhancements over the previous version. (BZ#1205554)

Several enhancements are described in the Red Hat Enterprise Linux 7.2 Release Notes, linked to in the References section :

* SSSD smart card support (BZ#854396)

* Cache authentication in SSSD (BZ#910187)

* SSSD supports overriding automatically discovered AD site (BZ#1163806)

* SSSD can now deny SSH access to locked accounts (BZ#1175760)

* SSSD enables UID and GID mapping on individual clients (BZ#1183747)

* Background refresh of cached entries (BZ#1199533)

* Multi-step prompting for one-time and long-term passwords (BZ#1200873)

* Caching for initgroups operations (BZ#1206575)

Bugs fixed :

* When the SELinux user content on an IdM server was set to an empty string, the SSSD SELinux evaluation utility returned an error.
(BZ#1192314)

* If the ldap_child process failed to initialize credentials and exited with an error multiple times, operations that create files in some cases started failing due to an insufficient amount of i-nodes.
(BZ#1198477)

* The SRV queries used a hard-coded TTL timeout, and environments that wanted the SRV queries to be valid for a certain time only were blocked. Now, SSSD parses the TTL value out of the DNS packet.
(BZ#1199541)

* Previously, initgroups operation took an excessive amount of time.
Now, logins and ID processing are faster for setups with AD back end and disabled ID mapping. (BZ#1201840)

* When an IdM client with Red Hat Enterprise Linux 7.1 or later was connecting to a server with Red Hat Enterprise Linux 7.0 or earlier, authentication with an AD trusted domain caused the sssd_be process to terminate unexpectedly. (BZ#1202170)

* If replication conflict entries appeared during HBAC processing, the user was denied access. Now, the replication conflict entries are skipped and users are permitted access. (BZ#1202245)

* The array of SIDs no longer contains an uninitialized value and SSSD no longer crashes. (BZ#1204203)

* SSSD supports GPOs from different domain controllers and no longer crashes when processing GPOs from different domain controllers.
(BZ#1205852)

* SSSD could not refresh sudo rules that contained groups with special characters, such as parentheses, in their name. (BZ#1208507)

* The IPA names are not qualified on the client side if the server already qualified them, and IdM group members resolve even if default_domain_suffix is used on the server side. (BZ#1211830)

* The internal cache cleanup task has been disabled by default to improve performance of the sssd_be process. (BZ#1212489)

* Now, default_domain_suffix is not considered anymore for autofs maps. (BZ#1216285)

* The user can set subdomain_inherit=ignore_group-members to disable fetching group members for trusted domains. (BZ#1217350)

* The group resolution failed with an error message: 'Error: 14 (Bad address)'. The binary GUID handling has been fixed. (BZ#1226119)

Enhancements added :

* The description of default_domain_suffix has been improved in the manual pages. (BZ#1185536)

* With the new '%0' template option, users on SSSD IdM clients can now use home directories set on AD. (BZ#1187103)

All sssd users are advised to upgrade to these updated packages, which correct these issues and add these enhancements.

It was found that SSSD's Privilege Attribute Certificate (PAC) responder plug-in would leak a small amount of memory on each authentication request. A remote attacker could potentially use this flaw to exhaust all available memory on the system by making repeated requests to a Kerberized daemon application configured to authenticate using the PAC responder plug-in. (CVE-2015-5292)

This update also fixes the following bugs :

  - Previously, SSSD did not correctly handle sudo rules     that applied to groups with names containing special     characters, such as the '(' opening parenthesis sign.
    Consequently, SSSD skipped such sudo rules. The internal     sysdb search has been modified to escape special     characters when searching for objects to which sudo     rules apply. As a result, SSSD applies the described     sudo rules as expected.

  - Prior to this update, SSSD did not correctly handle     group names containing special Lightweight Directory     Access Protocol (LDAP) characters, such as the '(' or     ')' parenthesis signs. When a group name contained one     or more such characters, the internal cache cleanup     operation failed with an I/O error. With this update,     LDAP special characters in the Distinguished Name (DN)     of a cache entry are escaped before the cleanup     operation starts. As a result, the cleanup operation     completes successfully in the described situation.

  - Applications performing Kerberos authentication     previously increased the memory footprint of the     Kerberos plug-in that parses the Privilege Attribute     Certificate (PAC) information. The plug-in has been     updated to free the memory it allocates, thus fixing     this bug.

  - Previously, when malformed POSIX attributes were defined     in an Active Directory (AD) LDAP server, SSSD     unexpectedly switched to offline mode. This update     relaxes certain checks for AD POSIX attribute validity.
    As a result, SSSD now works as expected even when     malformed POSIX attributes are present in AD and no     longer enters offline mode in the described situation.

After installing the update, the sssd service will be restarted automatically. Additionally, all running applications using the PAC responder plug-in must be restarted for the changes to take effect.

Updated sssd packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 6.

Red Hat Product Security has rated this update as having Low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

The System Security Services Daemon (SSSD) service provides a set of daemons to manage access to remote directories and authentication mechanisms. It also provides the Name Service Switch (NSS) and the Pluggable Authentication Modules (PAM) interfaces toward the system, and a pluggable back-end system to connect to multiple different account sources.

It was found that SSSD's Privilege Attribute Certificate (PAC) responder plug-in would leak a small amount of memory on each authentication request. A remote attacker could potentially use this flaw to exhaust all available memory on the system by making repeated requests to a Kerberized daemon application configured to authenticate using the PAC responder plug-in. (CVE-2015-5292)

This update also fixes the following bugs :

* Previously, SSSD did not correctly handle sudo rules that applied to groups with names containing special characters, such as the '(' opening parenthesis sign. Consequently, SSSD skipped such sudo rules.
The internal sysdb search has been modified to escape special characters when searching for objects to which sudo rules apply. As a result, SSSD applies the described sudo rules as expected.
(BZ#1258398)

* Prior to this update, SSSD did not correctly handle group names containing special Lightweight Directory Access Protocol (LDAP) characters, such as the '(' or ')' parenthesis signs. When a group name contained one or more such characters, the internal cache cleanup operation failed with an I/O error. With this update, LDAP special characters in the Distinguished Name (DN) of a cache entry are escaped before the cleanup operation starts. As a result, the cleanup operation completes successfully in the described situation.
(BZ#1264098)

* Applications performing Kerberos authentication previously increased the memory footprint of the Kerberos plug-in that parses the Privilege Attribute Certificate (PAC) information. The plug-in has been updated to free the memory it allocates, thus fixing this bug. (BZ#1268783)

* Previously, when malformed POSIX attributes were defined in an Active Directory (AD) LDAP server, SSSD unexpectedly switched to offline mode. This update relaxes certain checks for AD POSIX attribute validity. As a result, SSSD now works as expected even when malformed POSIX attributes are present in AD and no longer enters offline mode in the described situation. (BZ#1268784)

All sssd users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. After installing the update, the sssd service will be restarted automatically.
Additionally, all running applications using the PAC responder plug-in must be restarted for the changes to take effect.

From Red Hat Security Advisory 2015:2019 :

Updated sssd packages that fix one security issue and several bugs are now available for Red Hat Enterprise Linux 6.

Red Hat Product Security has rated this update as having Low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

The System Security Services Daemon (SSSD) service provides a set of daemons to manage access to remote directories and authentication mechanisms. It also provides the Name Service Switch (NSS) and the Pluggable Authentication Modules (PAM) interfaces toward the system, and a pluggable back-end system to connect to multiple different account sources.

It was found that SSSD's Privilege Attribute Certificate (PAC) responder plug-in would leak a small amount of memory on each authentication request. A remote attacker could potentially use this flaw to exhaust all available memory on the system by making repeated requests to a Kerberized daemon application configured to authenticate using the PAC responder plug-in. (CVE-2015-5292)

This update also fixes the following bugs :

* Previously, SSSD did not correctly handle sudo rules that applied to groups with names containing special characters, such as the '(' opening parenthesis sign. Consequently, SSSD skipped such sudo rules.
The internal sysdb search has been modified to escape special characters when searching for objects to which sudo rules apply. As a result, SSSD applies the described sudo rules as expected.
(BZ#1258398)

* Prior to this update, SSSD did not correctly handle group names containing special Lightweight Directory Access Protocol (LDAP) characters, such as the '(' or ')' parenthesis signs. When a group name contained one or more such characters, the internal cache cleanup operation failed with an I/O error. With this update, LDAP special characters in the Distinguished Name (DN) of a cache entry are escaped before the cleanup operation starts. As a result, the cleanup operation completes successfully in the described situation.
(BZ#1264098)

* Applications performing Kerberos authentication previously increased the memory footprint of the Kerberos plug-in that parses the Privilege Attribute Certificate (PAC) information. The plug-in has been updated to free the memory it allocates, thus fixing this bug. (BZ#1268783)

* Previously, when malformed POSIX attributes were defined in an Active Directory (AD) LDAP server, SSSD unexpectedly switched to offline mode. This update relaxes certain checks for AD POSIX attribute validity. As a result, SSSD now works as expected even when malformed POSIX attributes are present in AD and no longer enters offline mode in the described situation. (BZ#1268784)

All sssd users are advised to upgrade to these updated packages, which contain backported patches to correct these issues. After installing the update, the sssd service will be restarted automatically.
Additionally, all running applications using the PAC responder plug-in must be restarted for the changes to take effect.

ID	Name	Product	Family	Severity
89413	Fedora 21 : sssd-1.12.5-4.fc21 (2015-cdea5324a8)	Nessus	Fedora Local Security Checks	medium
89296	Fedora 22 : sssd-1.13.1-2.fc22 (2015-7b47df69d3)	Nessus	Fedora Local Security Checks	medium
89171	Fedora 23 : sssd-1.13.1-2.fc23 (2015-202c127199)	Nessus	Fedora Local Security Checks	medium
87969	Amazon Linux AMI : sssd (ALAS-2016-635)	Nessus	Amazon Linux Local Security Checks	medium
87575	Scientific Linux Security Update : sssd on SL7.x x86_64 (20151119)	Nessus	Scientific Linux Local Security Checks	medium
87151	CentOS 7 : sssd (CESA-2015:2355)	Nessus	CentOS Local Security Checks	medium
87095	Oracle Linux 7 : sssd (ELSA-2015-2355)	Nessus	Oracle Linux Local Security Checks	medium
86983	RHEL 7 : sssd (RHSA-2015:2355)	Nessus	Red Hat Local Security Checks	medium
86846	Scientific Linux Security Update : sssd on SL6.x i386/x86_64 (20151110)	Nessus	Scientific Linux Local Security Checks	medium
86845	RHEL 6 : sssd (RHSA-2015:2019)	Nessus	Red Hat Local Security Checks	medium
86843	Oracle Linux 6 : sssd (ELSA-2015-2019)	Nessus	Oracle Linux Local Security Checks	medium
86831	CentOS 6 : sssd (CESA-2015:2019)	Nessus	CentOS Local Security Checks	medium

Detections

Analytics

CVE-2015-5292

high

Tenable Plugins

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium

medium