[UNIX] Vulnerability in OpenCA Signature Verification

From: SecuriTeam (support_at_securiteam.com)
Date: 01/19/04

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    Date: 19 Jan 2004 12:56:17 +0200
    
    

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      Vulnerability in OpenCA Signature Verification
    ------------------------------------------------------------------------

    SUMMARY

     <http://www.openca.org/> OpenCA Project is "an open organization aimed to
    provide a framework for PKI studying and development of related projects".

    A flaw in OpenCA could cause OpenCA to accept a signature from a
    certificate if the certificate's chain is trusted byte chain directory of
    OpenCA. This means that a certificate from another PKI can authorize
    operations on the used PKI if the chain of the used signature certificate
    can establish a trust relationship to the actually used PKI.

    DETAILS

    Vulnerable Systems:
     * OpenCA version 0.9.1.6 and prior

    Immune Systems:
     * OpenCA version 0.9.1.7 and newer

    CVE Information:
     <http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0004>
    CAN-2004-0004

    OpenCA has a library for common crypto operations - crypto-utils.lib. This
    library includes a function to check a signature(libCheckSignature). The
    function loads the used signature certificate from OpenCA's database and
    finally ensures that the used signature certificate is identical with the
    certificate in the database. The comparison of the certificate in the
    database and the certificate of the signer was only performed on base of
    the serial of the certificate. The design of the function can cause the
    acceptance of a signature if the chain of the signature can create a trust
    relationship to the chain directory of OpenCA and a certificate with a
    matching serial exists in the used PKI.
    A security risk is present for people who are using digital signatures to
    secure approved requests or role based access control (RBAC).

    Workaround:
    The following patch can be applied to fix the vulnerability:

    -----BEGIN PATCH-----
    --- src/common/lib/functions/crypto-utils.lib 2004-01-15
    12:10:45.000000000 +0100
    +++ src/common/lib/functions/crypto-utils.lib.new 2004-01-15
    12:10:06.000000000 +0100
    @@ -201,7 +201,7 @@
                                                    "__ERRVAL__",
    $OpenCA::X509::errval);
                             return undef;
                     }

    - last if ( $tmpCert->getSerial() eq $sigCert->getSerial()
    );
    + last if ( $tmpCert->getPEM() eq $sigCert->getPEM() );
                     $sigCert = undef;
             }

    -----END PATCH-----

    Solution:
    Upgrade to 0.9.1.7 and use newer snapshots than
    openca-SNAP-20040114.tar.gz.

    ADDITIONAL INFORMATION

    The information has been provided by
    <mailto:michael.bel@cms.hu-berlin.de> Michael Bell.

    The original article can be found at:
    <http://www.openca.org/news/CAN-2004-0004.txt>
    http://www.openca.org/news/CAN-2004-0004.txt.

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