Integer overflow in the rsCStrExtendBuf function in runtime/stringbuf.c in the imfile module in rsyslog 4.x before 4.6.6, 5.x before 5.7.4, and 6.x before 6.1.4 allows local users to cause a denial of service (daemon hang) via a large file, which triggers a heap-based buffer overflow.

The remote host is affected by the vulnerability described in GLSA-201412-35 (RSYSLOG: Denial of Service)

    Multiple vulnerabilities have been discovered in RSYSLOG. Please review       the CVE identifiers referenced below for details.
  Impact :

    A context-dependent attacker may be able to create a Denial of Service       condition.
  Workaround :

    There is no known workaround at this time.

A numeric truncation error, leading to a heap-based buffer overflow, was found in the way the rsyslog imfile module processed text files containing long lines. An attacker could use this flaw to crash the rsyslogd daemon or, possibly, execute arbitrary code with the privileges of rsyslogd, if they are able to cause a long line to be written to a log file that rsyslogd monitors with imfile. The imfile module is not enabled by default. (CVE-2011-4623)

The remote Oracle Linux 6 host has packages installed that are affected by a vulnerability as referenced in the ELSA-2012-0796 advisory.

    [5.8.10-2]
    - add patch to update information on debugging in the man page       Resolves: #820311
    - add patch to prevent debug output to stdout after forking       Resolves: #820996
    - add patch to support ssl certificates with domain names longer than 128 chars       Resolves: #822118

    [5.8.10-1]
    - rebase to rsyslog 5.8.10       Resolves: #803550       Resolves: #805424       Resolves: #813079       Resolves: #813084
    - consider lock file in 'status' action       Resolves: #807608
    - add impstats and imptcp modules
    - include new license text files
    - specify which versions of sysklogd are obsoleted

    [5.8.7-1]
    - rebase to rsyslog-5.8.7
      - change license from 'GPLv3+' to '(GPLv3+ and ASL 2.0)'         http://blog.gerhards.net/2012/01/rsyslog-licensing-update.html
      - remove patches obsoleted by rebase
      - add patches for better sysklogd compatibility (taken from upstream)
      - update included files for the new major version       Resolves: #672182       Resolves: #727380       Resolves: #756664       Resolves: #767527       Resolves: #769025
    - add several directories for storing auxiliary data       Resolves: #740420
    - fix source package URL

Tenable has extracted the preceding description block directly from the Oracle Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The rsyslog packages provide an enhanced, multi-threaded syslog daemon.

A numeric truncation error, leading to a heap-based buffer overflow, was found in the way the rsyslog imfile module processed text files containing long lines. An attacker could use this flaw to crash the rsyslogd daemon or, possibly, execute arbitrary code with the privileges of rsyslogd, if they are able to cause a long line to be written to a log file that rsyslogd monitors with imfile. The imfile module is not enabled by default. (CVE-2011-4623)

Bug fixes :

  - Several variables were incorrectly deinitialized with     Transport Layer Security (TLS) transport and keys in     PKCS#8 format. The rsyslogd daemon aborted with a     segmentation fault when keys in this format were     provided. Now, the variables are correctly     deinitialized.

  - Previously, the imgssapi plug-in initialization was     incomplete. As a result, the rsyslogd daemon aborted     when configured to provide a GSSAPI listener. Now, the     plug-in is correctly initialized.

  - The fully qualified domain name (FQDN) for the localhost     used in messages was the first alias found. This did not     always produce the expected result on multihomed hosts.
    With this update, the algorithm uses the alias that     corresponds to the hostname.

  - The gtls module leaked a file descriptor every time it     was loaded due to an error in the GnuTLS library. No new     files or network connections could be opened when the     limit for the file descriptor count was reached. This     update modifies the gtls module so that it is not     unloaded during the process lifetime.

  - rsyslog could not override the hostname to set an     alternative hostname for locally generated messages.
    Now, the local hostname can be overridden.

  - The rsyslogd init script did not pass the lock file path     to the 'status' action. As a result, the lock file was     ignored and a wrong exit code was returned. This update     modifies the init script to pass the lock file to the     'status' action. Now, the correct exit code is returned.

  - Data could be incorrectly deinitialized when rsyslogd     was supplied with malformed spool files. The rsyslogd     daemon could be aborted with a segmentation fault. This     update modifies the underlying code to correctly     deinitialize the data.

  - Previously, deinitialization of non-existent data could,     in certain error cases, occur. As a result, rsyslogd     could abort with a segmentation fault when rsyslog was     configured to use a disk assisted queue without     specifying a spool file. With this update, the error     cases are handled gracefully.

  - The manual page wrongly stated that the '-d' option to     turn on debugging caused the daemon to run in the     foreground, which was misleading as the current behavior     is to run in the background. Now, the manual page     reflects the correct behavior.

  - rsyslog attempted to write debugging messages to     standard output even when run in the background. This     resulted in the debugging information being written to     some other output. This was corrected and the debug     messages are no longer written to standard output when     run in the background.

  - The string buffer to hold the distinguished name (DN) of     a certificate was too small. DNs with more than 128     characters were not displayed. This update enlarges the     buffer to process longer DNs.

Enhancements :

  - Support for rate limiting and multi-line message     capability. Now, rsyslogd can limit the number of     messages it accepts through a UNIX socket.

  - The addition of the '/etc/rsyslog.d/' configuration     directory to supply syslog configuration files.

All users of rsyslog are advised to upgrade to these updated packages, which upgrade rsyslog to version 5.8.10 and correct these issues and add these enhancements. After installing this update, the rsyslog daemon will be restarted automatically.

Updated rsyslog packages that fix one security issue, multiple bugs, and add two enhancements are now available for Red Hat Enterprise Linux 6.

The Red Hat Security Response Team has rated this update as having moderate 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 rsyslog packages provide an enhanced, multi-threaded syslog daemon.

A numeric truncation error, leading to a heap-based buffer overflow, was found in the way the rsyslog imfile module processed text files containing long lines. An attacker could use this flaw to crash the rsyslogd daemon or, possibly, execute arbitrary code with the privileges of rsyslogd, if they are able to cause a long line to be written to a log file that rsyslogd monitors with imfile. The imfile module is not enabled by default. (CVE-2011-4623)

Bug fixes :

* Several variables were incorrectly deinitialized with Transport Layer Security (TLS) transport and keys in PKCS#8 format. The rsyslogd daemon aborted with a segmentation fault when keys in this format were provided. Now, the variables are correctly deinitialized. (BZ#727380)

* Previously, the imgssapi plug-in initialization was incomplete. As a result, the rsyslogd daemon aborted when configured to provide a GSSAPI listener. Now, the plug-in is correctly initialized.
(BZ#756664)

* The fully qualified domain name (FQDN) for the localhost used in messages was the first alias found. This did not always produce the expected result on multihomed hosts. With this update, the algorithm uses the alias that corresponds to the hostname. (BZ#767527)

* The gtls module leaked a file descriptor every time it was loaded due to an error in the GnuTLS library. No new files or network connections could be opened when the limit for the file descriptor count was reached. This update modifies the gtls module so that it is not unloaded during the process lifetime. (BZ#803550)

* rsyslog could not override the hostname to set an alternative hostname for locally generated messages. Now, the local hostname can be overridden. (BZ#805424)

* The rsyslogd init script did not pass the lock file path to the 'status' action. As a result, the lock file was ignored and a wrong exit code was returned. This update modifies the init script to pass the lock file to the 'status' action. Now, the correct exit code is returned. (BZ#807608)

* Data could be incorrectly deinitialized when rsyslogd was supplied with malformed spool files. The rsyslogd daemon could be aborted with a segmentation fault. This update modifies the underlying code to correctly deinitialize the data. (BZ#813079)

* Previously, deinitialization of non-existent data could, in certain error cases, occur. As a result, rsyslogd could abort with a segmentation fault when rsyslog was configured to use a disk assisted queue without specifying a spool file. With this update, the error cases are handled gracefully. (BZ#813084)

* The manual page wrongly stated that the '-d' option to turn on debugging caused the daemon to run in the foreground, which was misleading as the current behavior is to run in the background. Now, the manual page reflects the correct behavior. (BZ#820311)

* rsyslog attempted to write debugging messages to standard output even when run in the background. This resulted in the debugging information being written to some other output. This was corrected and the debug messages are no longer written to standard output when run in the background. (BZ#820996)

* The string buffer to hold the distinguished name (DN) of a certificate was too small. DNs with more than 128 characters were not displayed. This update enlarges the buffer to process longer DNs.
(BZ#822118)

Enhancements :

* Support for rate limiting and multi-line message capability. Now, rsyslogd can limit the number of messages it accepts through a UNIX socket. (BZ#672182)

* The addition of the '/etc/rsyslog.d/' configuration directory to supply syslog configuration files. (BZ#740420)

All users of rsyslog are advised to upgrade to these updated packages, which upgrade rsyslog to version 5.8.10 and correct these issues and add these enhancements. After installing this update, the rsyslog daemon will be restarted automatically.

A vulnerability has been discovered and corrected in rsyslog :

An integer signedness error, leading to heap based buffer overflow was found in the way the imfile module of rsyslog, an enhanced system logging and kernel message trapping daemon, processed text files larger than 64 KB. When the imfile rsyslog module was enabled, a local attacker could use this flaw to cause denial of service (rsyslogd daemon hang) via specially crafted message, to be logged (CVE-2011-4623).

The updated packages have been patched to correct this issue.

Peter Eisentraut discovered that Rsyslog would not properly perform input validation when configured to use imfile. If an attacker were able to craft messages in a file that Rsyslog monitored, an attacker could cause a denial of service. The imfile module is disabled by default in Ubuntu.

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

ID	Name	Product	Family	Severity
80240	GLSA-201412-35 : RSYSLOG: Denial of Service	Nessus	Gentoo Local Security Checks	high
69595	Amazon Linux AMI : rsyslog (ALAS-2012-105)	Nessus	Amazon Linux Local Security Checks	low
68549	Oracle Linux 6 : rsyslog (ELSA-2012-0796)	Nessus	Oracle Linux Local Security Checks	high
61348	Scientific Linux Security Update : rsyslog on SL6.x i386/x86_64 (20120620)	Nessus	Scientific Linux Local Security Checks	low
59920	CentOS 6 : rsyslog (CESA-2012:0796)	Nessus	CentOS Local Security Checks	low
59710	Mandriva Linux Security Advisory : rsyslog (MDVSA-2012:100)	Nessus	Mandriva Local Security Checks	low
59585	RHEL 6 : rsyslog (RHSA-2012:0796)	Nessus	Red Hat Local Security Checks	low
57662	Ubuntu 11.04 : rsyslog vulnerability (USN-1338-1)	Nessus	Ubuntu Local Security Checks	low

Detections

Analytics

CVE-2011-4623

medium

Tenable Plugins

high

low

high

low

low

low

low

low