/* packet-gpef.c * Routines for dissection of Group Policy : Encrypted File System Extension * Described in Microsoft document MS-GPEF.pdf * Copyright 2008, Ronnie Sahlberg * * Wireshark - Network traffic analyzer * By Gerald Combs * Copyright 1998 Gerald Combs * * SPDX-License-Identifier: GPL-2.0-or-later */ #include "config.h" #include #include "packet-windows-common.h" #include #include "packet-x509af.h" void proto_register_gpef(void); static int proto_gpef; static int hf_gpef_keycount; static int hf_gpef_efskey; static int hf_gpef_efskey_length1; static int hf_gpef_efskey_length2; static int hf_gpef_efskey_sid_offset; static int hf_gpef_efskey_cert_offset; static int hf_gpef_efskey_cert_length; static int hf_gpef_efskey_certificate; static int ett_gpef; static int ett_gpef_efskey; /* MS-GPEF section 2.2.1.2.2 EfsKey*/ static int dissect_gpef_efskey(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *parent_tree) { proto_item *item = NULL; proto_tree *tree = NULL; int old_offset = offset; uint32_t length1, sid_offset; uint32_t cert_length, cert_offset; tvbuff_t *next_tvb; asn1_ctx_t asn1_ctx; asn1_ctx_init(&asn1_ctx, ASN1_ENC_BER, true, pinfo); if (parent_tree) { item = proto_tree_add_item(parent_tree, hf_gpef_efskey, tvb, -1, -1, ENC_NA); tree = proto_item_add_subtree(item, ett_gpef_efskey); } /* length 1 */ length1 = tvb_get_letohl(tvb, offset); proto_tree_add_item(tree, hf_gpef_efskey_length1, tvb, offset, 4, ENC_LITTLE_ENDIAN); offset += 4; /* length 2 */ proto_tree_add_item(tree, hf_gpef_efskey_length2, tvb, offset, 4, ENC_LITTLE_ENDIAN); offset += 4; /* sid offset */ sid_offset = tvb_get_letohl(tvb, offset); proto_tree_add_item(tree, hf_gpef_efskey_sid_offset, tvb, offset, 4, ENC_LITTLE_ENDIAN); offset += 4; /* reserved */ offset += 4; /* cert length */ cert_length = tvb_get_letohl(tvb, offset); proto_tree_add_item(tree, hf_gpef_efskey_cert_length, tvb, offset, 4, ENC_LITTLE_ENDIAN); offset += 4; /* cert offset */ cert_offset = tvb_get_letohl(tvb, offset); proto_tree_add_item(tree, hf_gpef_efskey_cert_offset, tvb, offset, 4, ENC_LITTLE_ENDIAN); /*offset += 4;*/ /* reserved, must be 0x20 0x00 0x00 0x00 */ /*offset += 4;*/ /* sid */ dissect_nt_sid(tvb, old_offset+4+sid_offset, tree, "sid", NULL, -1); /* certificate */ next_tvb = tvb_new_subset_length(tvb, old_offset+4+cert_offset, cert_length); (void)dissect_x509af_Certificate(false, next_tvb, 0, &asn1_ctx, tree, hf_gpef_efskey_certificate); offset = old_offset + length1; proto_item_set_len(item, offset-old_offset); return offset; } /* MS-GPEF section 2.2.1.2.1 */ static int dissect_gpef_efsblob(tvbuff_t *tvb, packet_info *pinfo, proto_tree *parent_tree, void *data _U_) { int offset = 0; proto_tree *tree; proto_item *item; uint32_t count; item = proto_tree_add_item(parent_tree, proto_gpef, tvb, 0, -1, ENC_NA); tree = proto_item_add_subtree(item, ett_gpef); /* reserved, must be 0x01 0x00 0x01 0x00 */ offset += 4; /* key count */ count = tvb_get_letohl(tvb, offset); proto_tree_add_item(tree, hf_gpef_keycount, tvb, offset, 4, ENC_LITTLE_ENDIAN); offset += 4; while (count--) { offset = dissect_gpef_efskey(tvb, offset, pinfo, tree); } return offset; } void proto_register_gpef(void) { static hf_register_info hf[] = { { &hf_gpef_keycount, { "Key Count", "gpef.key_count", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_gpef_efskey_length1, { "Length1", "gpef.efskey.length1", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_gpef_efskey_length2, { "Length2", "gpef.efskey.length2", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_gpef_efskey_sid_offset, { "SID Offset", "gpef.efskey.sid_offset", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_gpef_efskey_cert_offset, { "Cert Offset", "gpef.efskey.cert_offset", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_gpef_efskey_cert_length, { "Cert Length", "gpef.efskey.cert_length", FT_UINT32, BASE_DEC, NULL, 0x0, NULL, HFILL }}, { &hf_gpef_efskey, { "EfsKey", "gpef.efskey", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL }}, { &hf_gpef_efskey_certificate, { "Certificate", "gpef.efskey.certificate", FT_NONE, BASE_NONE, NULL, 0x0, NULL, HFILL }}, }; static int *ett[] = { &ett_gpef, &ett_gpef_efskey, }; proto_gpef = proto_register_protocol("GPEF", "GPEF", "gpef"); proto_register_field_array(proto_gpef, hf, array_length(hf)); proto_register_subtree_array(ett, array_length(ett)); register_dissector("efsblob", dissect_gpef_efsblob, proto_gpef); } /* * Editor modelines - https://www.wireshark.org/tools/modelines.html * * Local variables: * c-basic-offset: 8 * tab-width: 8 * indent-tabs-mode: t * End: * * vi: set shiftwidth=8 tabstop=8 noexpandtab: * :indentSize=8:tabSize=8:noTabs=false: */