[UNIX] GWCC Insecure Temporary File Creation

From: SecuriTeam (support_at_securiteam.com)
Date: 09/19/05

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Date: 19 Sep 2005 10:33:06 +0200

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      GWCC Insecure Temporary File Creation
    ------------------------------------------------------------------------

    SUMMARY

    " <http://gwcc.sourceforge.net/> GWCC allows users to execute network
    utilities (ping, nslookup, traceroute) and workstation commands (netstat,
    df, process grep) from a single tabbed window."

    GWCC creates temporary files in an insecure manner that allow local
    attackers to perform symbolic link attacks.

    DETAILS

    Vulnerable Systems:
     * gwcc version 0.9.6-r2 and prior

    GWCC creates a constant temporary file on user home directory, or in the
    /tmp directory if the environment variable is null.

    An cause GWCC to create the temporary file name in the /tmp directory, and
    overwrite files using a symbolic link attack.

    Possible Patch:
     <http://bugs.gentoo.org/attachment.cgi?id=67477>
    http://bugs.gentoo.org/attachment.cgi?id=67477:
    diff -ru gwcc-0.9.6/src/callbacks.c gwcc-0.9.6.new/src/callbacks.c
    --- gwcc-0.9.6/src/callbacks.c 2001-07-26 19:50:16.000000000 +0100
    +++ gwcc-0.9.6.new/src/callbacks.c 2005-09-02 14:19:39.344296608 +0100
    @@ -1697,10 +1697,14 @@
         }
     
         // Create temp file to be Printed (via file saving function).
    - perform_file_save("temp", NULL);
    + if (perform_file_save("temp", NULL) != 0)
    + return;
     
         // Pipe print command and voila!, the doc is printed.
    - strcat(print_command, " /tmp/gwcc_out.txt");
    + snprintf (print_command + strlen(print_command),
    + sizeof(print_command) - strlen(print_command) - 1,
    + " %s%s", getenv("HOME"), "/gwcc_temp.txt");
    +
         if (system(print_command) == -1) {
     // sprintf(entry_text, "The System Call '%s' failed!", print_command);
             
    gnome_dialog_run_and_close(GNOME_DIALOG(gnome_error_dialog(entry_text)));
    diff -ru gwcc-0.9.6/src/prefs.c gwcc-0.9.6.new/src/prefs.c
    --- gwcc-0.9.6/src/prefs.c 2001-07-15 07:00:30.000000000 +0100
    +++ gwcc-0.9.6.new/src/prefs.c 2005-09-02 14:04:41.998713872 +0100
    @@ -27,6 +27,7 @@
        #include <string.h> /* for string functs */
        #include <fcntl.h> /* for open() command */
        #include <sys/stat.h> /* for mkdir() funct */
    + #include <errno.h>
        #include "prefs.h"
        #include "interface.h"
        #include "support.h"
    diff -ru gwcc-0.9.6/src/utils.c gwcc-0.9.6.new/src/utils.c
    --- gwcc-0.9.6/src/utils.c 2001-05-15 04:42:21.000000000 +0100
    +++ gwcc-0.9.6.new/src/utils.c 2005-09-02 14:20:07.050084688 +0100
    @@ -91,16 +91,15 @@
             }
             gtk_widget_destroy(GTK_WIDGET(user_data));
         }
    - else if (strcmp(operation, "temp") == 0) {
    - strcat(file_name, "/tmp/gwcc_out.txt");
    - }
    - else if (strcmp(operation, "home") == 0) {
    - env_homedir = getenv("HOME");
    - if (env_homedir == NULL) {
    - strcpy(env_homedir, "/tmp");
    - }
    - strcpy(file_name, env_homedir);
    - strcat(file_name, "/gwcc_out.txt");
    + else if ((strcmp(operation, "temp") == 0) || strcmp(operation, "home")
    == 0) {
    + env_homedir = getenv("HOME");
    + if (env_homedir == NULL)
    + return 1;
    + strcpy(file_name, env_homedir);
    + if (strcmp(operation, "home") == 0)
    + strcat(file_name, "/gwcc_out.txt");
    + else
    + strcat(file_name, "/gwcc_temp.txt");
         }
     
         // Get the number (int) of current notebook page (0...n-1),

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:exploits@zataz.net> ZATAZ
    Audits.
    The original article can be found at:
    <http://www.zataz.net/adviso/gwcc-09052005.txt>
    http://www.zataz.net/adviso/gwcc-09052005.txt

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