full-disclosure - local buffer overflow in htpasswd for apache 1.3.31 not fixed in .33?

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Message-ID: <20041029175340.GA28655@vapid.dhs.org>
From: lwc at vapid.ath.cx (Larry Cashdollar)
Subject: local buffer overflow in htpasswd for apache 1.3.31 not fixed in .33?

This was posted on the full-disclosure list sept 16 2004 by
Luiz Fernando.

http://archives.neohapsis.com/archives/fulldisclosure/2004-09/0547.html

The nessus check for this vulnerability recommends upgrading to
Apache version 1.3.32:

http://cgi.nessus.org/plugins/dump.php3?id=14771

But in Apache 1.3.33:

lachoy# grep strcpy /install/src/apache_1.3.33/src/support/htpasswd.c
    strcpy(record, user);
        strcpy(pwfilename, argv[i]);
    strcpy(user, argv[i + 1]);
        strcpy(password, argv[i + 2]);
            strcpy(scratch, line);

It is still vulnerable.

I patched my version that seemed to thwart the exploit offered by
Luiz.  Here is the diff:

root@...choy:~/tes/apache_1.3.33/src/support# diff -uN  htpasswd.orig.c
htpasswd.c
--- htpasswd.orig.c     2004-10-28 18:20:13.000000000 -0400
+++ htpasswd.c  2004-10-28 18:17:25.000000000 -0400
@@ -202,9 +202,9 @@
        ap_cpystrn(record, "resultant record too long", (rlen - 1));
        return ERR_OVERFLOW;
     }
-    strcpy(record, user);
+    strncpy(record, user,MAX_STRING_LEN - 1);
     strcat(record, ":");
-    strcat(record, cpw);
+    strncat(record, cpw,MAX_STRING_LEN - 1);
     return 0;
 }

@@ -410,14 +410,14 @@
            fprintf(stderr, "%s: filename too long\n", argv[0]);
            return ERR_OVERFLOW;
        }
-       strcpy(pwfilename, argv[i]);
+       strncpy(pwfilename, argv[i], MAX_STRING_LEN-1);
        if (strlen(argv[i + 1]) > (sizeof(user) - 1)) {
            fprintf(stderr, "%s: username too long (>%lu)\n", argv[0],
                    (unsigned long)(sizeof(user) - 1));
            return ERR_OVERFLOW;
        }
     }
-    strcpy(user, argv[i + 1]);
+    strncpy(user, argv[i + 1],MAX_STRING_LEN-1);
     if ((arg = strchr(user, ':')) != NULL) {
        fprintf(stderr, "%s: username contains illegal character
'%c'\n",
                argv[0], *arg);
@@ -429,7 +429,7 @@
                    (unsigned long)(sizeof(password) - 1));
            return ERR_OVERFLOW;
        }
-       strcpy(password, argv[i + 2]);
+       strncpy(password, argv[i + 2],MAX_STRING_LEN - 1 );
     }

 #ifdef WIN32
@@ -553,7 +553,7 @@
                putline(ftemp, line);
                continue;
            }
-           strcpy(scratch, line);
+           strncpy(scratch, line,MAX_STRING_LEN -1);
            /*
             * See if this is our user.
             */


Larry W. Cashdollar
http://vapid.ath.cx