This alert is being posted to Bugtraq as our public release of the
vulnerability discovered in Sendmail by Cade Cairns <cairnscsecurityfocus.com>.

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                              Security Alert

Subject: Sendmail Debugger Arbitrary Code Execution Vulnerability
BUGTRAQ ID: 3163 CVE ID: CAN-2001-0653
Published: August 17, 2001 MT Updated: August 20, 2001 MT

Remote: No Local: Yes
Availability: Always Authentication: Not Required
Credibility: Vendor Confirmed Ease: No Exploit Available
Class: Input Validation Error

Impact: 10.00 Severity: 7.50 Urgency: 6.58

Last Change: Updated packages that rectify this issue are now available
              from Sendmail.
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Vulnerable Systems:

  Sendmail Consortium Sendmail 8.12beta7
  Sendmail Consortium Sendmail 8.12beta5
  Sendmail Consortium Sendmail 8.12beta16
  Sendmail Consortium Sendmail 8.12beta12
  Sendmail Consortium Sendmail 8.12beta10
  Sendmail Consortium Sendmail 8.11.5
  Sendmail Consortium Sendmail 8.11.4
  Sendmail Consortium Sendmail 8.11.3
  Sendmail Consortium Sendmail 8.11.2
  Sendmail Consortium Sendmail 8.11.1
  Sendmail Consortium Sendmail 8.11

Non-Vulnerable Systems:

Summary:

  Sendmail contains an input validation error, may lead to the execution
  of arbitrary code with elevated privileges.

Impact:

  Local users may be able to write arbitrary data to process memory,
  possibly allowing the execution of code/commands with elevated
  privileges.

Technical Description:

  An input validation error exists in Sendmail's debugging functionality.

  The problem is the result of the use of signed integers in the
  program's tTflag() function, which is responsible for processing
  arguments supplied from the command line with the '-d' switch and
  writing the values to it's internal "trace vector." The vulnerability
  exists because it is possible to cause a signed integer overflow by
  supplying a large numeric value for the 'category' part of the debugger
  arguments. The numeric value is used as an index for the trace vector.

  Before the vector is written to, a check is performed to ensure that
  the supplied index value is not greater than the size of the vector.
  However, because a signed integer comparison is used, it is possible to
  bypass the check by supplying the signed integer equivalent of a
  negative value. This may allow an attacker to write data to anywhere
  within a certain range of locations in process memory.

  Because the '-d' command-line switch is processed before the program
  drops its elevated privileges, this could lead to a full system
  compromise. This vulnerability has been successfully exploited in a
  laboratory environment.

Attack Scenarios:

  An attacker with local access must determine the memory offsets of the
  program's internal tTdvect variable and the location to which he or she
  wishes to have data written.

  The attacker must craft in architecture specific binary code the
  commands (or 'shellcode') to be executed with higher privilege. The
  attacker must then run the program, using the '-d' flag to overwrite a
  function return address with the location of the supplied shellcode.

Exploits:

  Currently the SecurityFocus staff are not aware of any exploits for
  this issue. If you feel we are in error or are aware of more recent
  information, please mail us at: vuldbsecurityfocus.com
  <mailto:vuldbsecurityfocus.com>.

Mitigating Strategies:

  Restrict local access to trusted users only.

Solutions:

  Below is a statement from the Sendmail Consortium regarding this issue:

  --------------------
  This vulnerability, present in sendmail open source versions between
  8.11.0 and 8.11.5 has been corrected in 8.11.6. sendmail 8.12.0.Beta
  users should upgrade to 8.12.0.Beta19. The problem was not present in
  8.10 or earlier versions. However, as always, we recommend using the
  latest version. Note that this problem is not remotely exploitable.
  Additionally, sendmail 8.12 will no longer uses a set-user-id root
  binary by default.
  --------------------

  Updated packages that rectify this issue are available from the vendor:

  For Sendmail Consortium Sendmail 8.11:

    Sendmail Consortium upgrade sendmail 8.11.6
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.11.6.tar.gz

  For Sendmail Consortium Sendmail 8.11.1:

    Sendmail Consortium upgrade sendmail 8.11.6
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.11.6.tar.gz

  For Sendmail Consortium Sendmail 8.11.2:

    Sendmail Consortium upgrade sendmail 8.11.6
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.11.6.tar.gz

  For Sendmail Consortium Sendmail 8.11.3:

    Sendmail Consortium upgrade sendmail 8.11.6
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.11.6.tar.gz

  For Sendmail Consortium Sendmail 8.11.4:

    Sendmail Consortium upgrade sendmail 8.11.6
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.11.6.tar.gz

  For Sendmail Consortium Sendmail 8.11.5:

    Sendmail Consortium upgrade sendmail 8.11.6
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.11.6.tar.gz

  For Sendmail Consortium Sendmail 8.12beta10:

    Sendmail Consortium upgrade sendmail 8.12.0 Beta19
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.12.0.Beta19.tar.gz

  For Sendmail Consortium Sendmail 8.12beta12:

    Sendmail Consortium upgrade sendmail 8.12.0 Beta19
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.12.0.Beta19.tar.gz

  For Sendmail Consortium Sendmail 8.12beta16:

    Sendmail Consortium upgrade sendmail 8.12.0 Beta19
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.12.0.Beta19.tar.gz

  For Sendmail Consortium Sendmail 8.12beta5:

    Sendmail Consortium upgrade sendmail 8.12.0 Beta19
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.12.0.Beta19.tar.gz

  For Sendmail Consortium Sendmail 8.12beta7:

    Sendmail Consortium upgrade sendmail 8.12.0 Beta19
    ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.12.0.Beta19.tar.gz

Credit:

  Discovered by Cade Cairns <cairnscsecurityfocus.com> of the Security
  Focus SIA Threat Analysis Team.

References:

  web page:
  Sendmail Homepage (Sendmail)
  http://www.sendmail.org/

ChangeLog:

  Aug 20, 2001: Updated packages that rectify this issue are now
                available from Sendmail.
  Aug 20, 2001: Updated versions of Sendmail will be available today at
                4:00 PDT.
  Aug 09, 2001: Initial analysis.

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HOW TO INTERPRET THIS ALERT

            BUGTRAQ ID: This is a unique identifier assigned to the
                        vulnerability by SecurityFocus.com.

                CVE ID: This is a unique identifier assigned to the
                        vulnerability by the CVE.

             Published: The date the vulnerability was first made public.

               Updated: The date the information was last updated.

                Remote: Whether this is a remotely exploitable
                        vulnerability.

                 Local: Whether this is a locally exploitable
                        vulnerability.

           Credibility: Describes how credible the information about the
                        vulnerability is. Possible values are:

                        Conflicting Reports: The are multiple conflicting
                        about the existance of the vulnerability.

                        Single Source: There is a single non-reliable
                        source reporting the existence of the
                        vulnerability.

                        Reliable Source: There is a single reliable source
                        reporting the existence of the vulnerability.

                        Conflicting Details: There is consensus on the
                        existence of the vulnerability but not it's
                        details.

                        Multiple Sources: There is consensus on the
                        existence and details of the vulnerability.

                        Vendor Confirmed: The vendor has confirmed the
                        vulnerability.

                 Class: The class of vulnerability. Possible values are:
                        Boundary Condition Error, Access Validation Error,
                        Origin Validation Error, Input Valiadtion Error,
                        Failure to Handle Exceptional Conditions, Race
                        Condition Error, Serialization Error, Atomicity
                        Error, Environment Error, and Configuration Error.

                  Ease: Rates how easiliy the vulnerability can be
                        exploited. Possible values are: No Exploit
                        Available, Exploit Available, and No Exploit
                        Required.

                Impact: Rates the impact of the vulnerability. It's range
                        is 1 through 10.

              Severity: Rates the severity of the vulnerability. It's range
                        is 1 through 10. It's computed from the impact
                        rating and remote flag. Remote vulnerabiliteis with
                        a high impact rating receive a high severity
                        rating. Local vulnerabilities with a low impact
                        rating receive a low severity rating.

               Urgency: Rates how quickly you should take action to fix or
                        mitigate the vulnerability. It's range is 1 through
                        10. It's computed from the severity rating, the
                        ease rating, and the credibility rating. High
                        severity vulnerabilities with a high ease rating,
                        and a high confidence rating have a higher urgency
                        rating. Low severity vulnerabilities with a low
                        ease rating, and a low confidence rating have a
                        lower urgency rating.

           Last Change: The last change made to the vulnerability
                        information.

    Vulnerable Systems: The list of vulnerable systems. A '+' preceding a
                        system name indicates that one of the system
                        components is vulnerable vulnerable. For example,
                        Windows 98 ships with Internet Explorer. So if a
                        vulnerability is found in IE you may see something
                        like: Microsoft Internet Explorer + Microsoft
                        Windows 98

Non-Vulnerable Systems: The list of non-vulnerable systems.

               Summary: A concise summary of the vulnerability.

                Impact: The impact of the vulnerability.

 Technical Description: The in-depth description of the vulnerability.

      Attack Scenarios: Ways an attacker may make use of the vulnerability.

              Exploits: Exploit intructions or programs.

 Mitigating Strategies: Ways to mitigate the vulnerability.

             Solutions: Solutions to the vulnerability.

                Credit: Information about who disclosed the vulnerability.

            References: Sources of information on the vulnerability.

     Related Resources: Resources that might be of additional value.

             ChangeLog: History of changes to the vulnerability record.

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                     Copyright 2001 SecurityFocus.com

                     https://alerts.securityfocus.com/

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