Fix KDC heap corruption vuln [CVE-2012-1015]

Fix KDC heap corruption vulnerability [MITKRB5-SA-2012-001
CVE-2012-1015].  The cleanup code in
kdc_handle_protected_negotiation() in kdc_util.c could free an
uninitialized pointer in some error conditions involving "similar"
enctypes and a failure in krb5_c_make_checksum().

Additionally, adjust the handling of "similar" enctypes to avoid
advertising enctypes that could lead to inadvertent triggering of this
vulnerability (possibly in unpatched KDCs).

Note that CVE-2012-1014 (also described in MITKRB5-SA-2012-001) only
applies to the krb5-1.10 branch and doesn't affect the master branch
or releases prior to krb5-1.10.

(cherry picked from commit 3551501359c6d2396fa4779d378ae165f5b37242)

ticket: 7225
version_fixed: 1.9.5
status: resolved

diff --git a/src/kdc/kdc_preauth.c b/src/kdc/kdc_preauth.c
index 52fb51a0c951f444c4f724b816d24303034b902f..fd3b580012c3e111a2675c7ab715aa75499a11d6 100644 (file)
--- a/src/kdc/kdc_preauth.c
+++ b/src/kdc/kdc_preauth.c
@@ -1562,7 +1562,8 @@ etype_info_helper(krb5_context context, krb5_kdc_req *request,
                 continue;
 
             }
-            if (request_contains_enctype(context, request, db_etype)) {
+            if (krb5_is_permitted_enctype(context, db_etype) &&
+                request_contains_enctype(context, request, db_etype)) {
                 retval = _make_etype_info_entry(context, client->princ,
                                                 client_key, db_etype,
                                                 &entry[i], etype_info2);

diff --git a/src/kdc/kdc_util.c b/src/kdc/kdc_util.c
index 2913738d2e65ecf84c176395828f06f616b33211..394094393f5c5b396667640f0db28296bde545b4 100644 (file)
--- a/src/kdc/kdc_util.c
+++ b/src/kdc/kdc_util.c
@@ -2469,6 +2469,7 @@ kdc_handle_protected_negotiation(krb5_data *req_pkt, krb5_kdc_req *request,
         return 0;
     pa.magic = KV5M_PA_DATA;
     pa.pa_type = KRB5_ENCPADATA_REQ_ENC_PA_REP;
+    memset(&checksum, 0, sizeof(checksum));
     retval = krb5_c_make_checksum(kdc_context,0, reply_key,
                                   KRB5_KEYUSAGE_AS_REQ, req_pkt, &checksum);
     if (retval != 0)

diff --git a/src/lib/kdb/kdb_default.c b/src/lib/kdb/kdb_default.c
index 18de7c75a01dcf3076b99bf54e1294c7d156a38a..ae184c417e5577dc81ef1997ec051dc2bc66902c 100644 (file)
--- a/src/lib/kdb/kdb_default.c
+++ b/src/lib/kdb/kdb_default.c
@@ -64,6 +64,9 @@ krb5_dbe_def_search_enctype(kcontext, dbentp, start, ktype, stype, kvno, kdatap)
     krb5_boolean        saw_non_permitted = FALSE;
 
     ret = 0;
+    if (ktype != -1 && !krb5_is_permitted_enctype(kcontext, ktype))
+        return KRB5_KDB_NO_PERMITTED_KEY;
+
     if (kvno == -1 && stype == -1 && ktype == -1)
         kvno = 0;