/*
* Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2007-2013 Sourcefire, Inc.
*
* Authors: Nigel Horne
*
* Acknowledgements: The algorithm was based on
* kdepim/ktnef/lib/ktnefparser.cpp from KDE.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <stdio.h>
#include <fcntl.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "clamav.h"
#include "others.h"
#include "mbox.h"
#include "tnef.h"
static int tnef_message(fmap_t *map, off_t *pos, uint16_t type, uint16_t tag, int32_t length, off_t fsize);
static int tnef_attachment(fmap_t *map, off_t *pos, uint16_t type, uint16_t tag, int32_t length, const char *dir, fileblob **fbref, off_t fsize);
static int tnef_header(fmap_t *map, off_t *pos, uint8_t *part, uint16_t *type, uint16_t *tag, int32_t *length);
#define TNEF_SIGNATURE 0x223E9f78
#define LVL_MESSAGE 0x01
#define LVL_ATTACHMENT 0x02
#define attMSGCLASS 0x8008
#define attBODY 0x800c
#define attATTACHDATA 0x800f /* Attachment Data */
#define attATTACHTITLE 0x8010 /* Attachment File Name */
#define attDATEMODIFIED 0x8020
#define attTNEFVERSION 0x9006
#define attOEMCODEPAGE 0x9007
#define host16(v) le16_to_host(v)
#define host32(v) le32_to_host(v)
/* a TNEF file must be at least this size */
#define MIN_SIZE (sizeof(uint32_t) + sizeof(uint16_t))
int
cli_tnef(const char *dir, cli_ctx *ctx)
{
uint32_t i32;
uint16_t i16;
fileblob *fb;
int ret, alldone;
off_t fsize, pos = 0;
fsize = ctx->fmap[0]->len;
if(fsize < (off_t) MIN_SIZE) {
cli_dbgmsg("cli_tngs: file too small, ignoring\n");
return CL_CLEAN;
}
if (fmap_readn(*ctx->fmap, &i32, pos, sizeof(uint32_t)) != sizeof(uint32_t)) {
/* The file is at least MIN_SIZE bytes, so it "can't" fail */
return CL_EREAD;
}
pos += sizeof(uint32_t);
if(host32(i32) != TNEF_SIGNATURE) {
return CL_EFORMAT;
}
if(fmap_readn(*ctx->fmap, &i16, pos, sizeof(uint16_t)) != sizeof(uint16_t)) {
/* The file is at least MIN_SIZE bytes, so it "can't" fail */
return CL_EREAD;
}
pos += sizeof(uint16_t);
fb = NULL;
ret = CL_CLEAN; /* we don't know if it's clean or not :-) */
alldone = 0;
do {
uint8_t part = 0;
uint16_t type = 0, tag = 0;
int32_t length = 0;
switch(tnef_header(*ctx->fmap, &pos, &part, &type, &tag, &length)) {
case 0:
alldone = 1;
break;
case 1:
break;
default:
/*
* Assume truncation, not file I/O error
*/
cli_warnmsg("cli_tnef: file truncated, returning CLEAN\n");
ret = CL_CLEAN;
alldone = 1;
break;
}
if(length == 0)
continue;
if(length < 0) {
cli_warnmsg("Corrupt TNEF header detected - length %d\n",
(int)length);
ret = CL_EFORMAT;
break;
}
if(alldone)
break;
switch(part) {
case LVL_MESSAGE:
cli_dbgmsg("TNEF - found message\n");
if(fb != NULL) {
fileblobDestroy(fb);
fb = NULL;
}
fb = fileblobCreate();
if(tnef_message(*ctx->fmap, &pos, type, tag, length, fsize) != 0) {
cli_dbgmsg("TNEF: Error reading TNEF message\n");
ret = CL_EFORMAT;
alldone = 1;
}
break;
case LVL_ATTACHMENT:
cli_dbgmsg("TNEF - found attachment\n");
if(tnef_attachment(*ctx->fmap, &pos, type, tag, length, dir, &fb, fsize) != 0) {
cli_dbgmsg("TNEF: Error reading TNEF attachment\n");
ret = CL_EFORMAT;
alldone = 1;
}
break;
case 0:
break;
default:
cli_warnmsg("TNEF - unknown level %d tag 0x%x\n", (int)part, (int)tag);
/*
* Dump the file incase it was part of an
* email that's about to be deleted
*/
if(cli_debug_flag) {
int fout = -1;
char *filename = cli_gentemp(ctx->engine->tmpdir);
char buffer[BUFSIZ];
if(filename)
fout = open(filename, O_WRONLY|O_CREAT|O_EXCL|O_TRUNC|O_BINARY, 0600);
if(fout >= 0) {
int count;
cli_warnmsg("Saving dump to %s: refer to https://www.clamav.net/documents/installing-clamav\n", filename);
pos = 0;
while ((count = fmap_readn(*ctx->fmap, buffer, pos, sizeof(buffer))) > 0) {
pos += count;
cli_writen(fout, buffer, count);
}
close(fout);
}
free(filename);
}
ret = CL_EFORMAT;
alldone = 1;
break;
}
} while(!alldone);
if(fb) {
cli_dbgmsg("cli_tnef: flushing final data\n");
if(fileblobGetFilename(fb) == NULL) {
cli_dbgmsg("Saving TNEF portion with an unknown name\n");
fileblobSetFilename(fb, dir, "tnef");
}
fileblobDestroy(fb);
fb = NULL;
}
cli_dbgmsg("cli_tnef: returning %d\n", ret);
return ret;
}
static int
tnef_message(fmap_t *map, off_t *pos, uint16_t type, uint16_t tag, int32_t length, off_t fsize)
{
off_t offset;
#ifdef CL_DEBUG
uint32_t i32;
char *string;
#endif
cli_dbgmsg("message tag 0x%x, type 0x%x, length %d\n", tag, type,
(int)length);
offset = *pos;
/*
* a lot of this stuff should be only discovered in debug mode...
*/
switch(tag) {
case attBODY:
cli_warnmsg("TNEF body not being scanned - if you believe this file contains a virus, submit it to www.clamav.net\n");
break;
#ifdef CL_DEBUG
case attTNEFVERSION:
/*assert(length == sizeof(uint32_t))*/
if(fmap_readn(map, &i32, *pos, sizeof(uint32_t)) != sizeof(uint32_t))
return -1;
(*pos) += sizeof(uint32_t);
i32 = host32(i32);
cli_dbgmsg("TNEF version %d\n", i32);
break;
case attOEMCODEPAGE:
/* 8 bytes, but just print the first 4 */
/*assert(length == sizeof(uint32_t))*/
if(fmap_readn(map, &i32, *pos, sizeof(uint32_t)) != sizeof(uint32_t))
return -1;
(*pos) += sizeof(uint32_t);
i32 = host32(i32);
cli_dbgmsg("TNEF codepage %d\n", i32);
break;
case attDATEMODIFIED:
/* 14 bytes, long */
break;
case attMSGCLASS:
if(length <= 0)
return -1;
string = cli_malloc(length + 1);
if(string == NULL) {
cli_errmsg("tnef_message: Unable to allocate memory for string\n");
return -1;
}
if((uint32_t)fmap_readn(map, string, *pos, (uint32_t)length) != (uint32_t)length) {
free(string);
return -1;
}
(*pos) += (uint32_t)length;
string[length] = '\0';
cli_dbgmsg("TNEF class %s\n", string);
free(string);
break;
default:
cli_dbgmsg("TNEF - unsupported message tag 0x%x type 0x%d length %d\n", tag, type, length);
break;
#endif
}
/*cli_dbgmsg("%lu %lu\n", (long)(offset + length), ftell(fp));*/
if(!CLI_ISCONTAINED2(0, fsize, offset, (off_t)length)) {
cli_dbgmsg("TNEF: Incorrect length field in tnef_message\n");
return -1;
}
(*pos) = offset + length;
/* Checksum - TODO, verify */
(*pos) += 2;
return 0;
}
static int
tnef_attachment(fmap_t *map, off_t *pos, uint16_t type, uint16_t tag, int32_t length, const char *dir, fileblob **fbref, off_t fsize)
{
uint32_t todo;
off_t offset;
char *string;
cli_dbgmsg("attachment tag 0x%x, type 0x%x, length %d\n", tag, type,
(int)length);
offset = *pos;
switch(tag) {
case attATTACHTITLE:
if(length <= 0)
return -1;
string = cli_malloc(length + 1);
if(string == NULL) {
cli_errmsg("tnef_attachment: Unable to allocate memory for string\n");
return -1;
}
if((uint32_t)fmap_readn(map, string, *pos, (uint32_t)length) != (uint32_t)length) {
free(string);
return -1;
}
(*pos) += (uint32_t)length;
string[length] = '\0';
cli_dbgmsg("TNEF filename %s\n", string);
if(*fbref == NULL) {
*fbref = fileblobCreate();
if(*fbref == NULL) {
free(string);
return -1;
}
}
fileblobSetFilename(*fbref, dir, string);
free(string);
break;
case attATTACHDATA:
if(*fbref == NULL) {
*fbref = fileblobCreate();
if(*fbref == NULL)
return -1;
}
todo = length;
while(todo) {
unsigned char buf[BUFSIZ];
int32_t got = fmap_readn(map, buf, *pos, MIN(sizeof(buf), todo));
if (got <= 0)
break;
(*pos) += got;
fileblobAddData(*fbref, buf, got);
todo -= got;
}
break;
default:
cli_dbgmsg("TNEF - unsupported attachment tag 0x%x type 0x%d length %d\n",
tag, type, (int)length);
break;
}
/*cli_dbgmsg("%lu %lu\n", (long)(offset + length), ftell(fp));*/
if(!CLI_ISCONTAINED2(0, fsize, (off_t)offset, (off_t)length)) {
cli_dbgmsg("TNEF: Incorrect length field in tnef_attachment\n");
return -1;
}
(*pos) = (long)(offset + length); /* shouldn't be needed */
(*pos) += 2;
return 0;
}
static int
tnef_header(fmap_t *map, off_t *pos, uint8_t *part, uint16_t *type, uint16_t *tag, int32_t *length)
{
uint32_t i32;
int rc;
if (fmap_readn(map, part, *pos, 1) != 1)
return 0;
(*pos)++;
if(*part == (uint8_t)0)
return 0;
rc = fmap_readn(map, &i32, *pos, sizeof(uint32_t));
if (rc != sizeof(uint32_t)) {
if(((*part == '\n') || (*part == '\r')) && (rc == 0)) {
/*
* trailing newline in the file, could be caused by
* broken quoted-printable encoding in the source
* message missing a final '='
*/
cli_dbgmsg("tnef_header: ignoring trailing newline\n");
return 0;
}
return -1;
}
(*pos) += sizeof(uint32_t);
i32 = host32(i32);
*tag = (uint16_t)(i32 & 0xFFFF);
*type = (uint16_t)((i32 & 0xFFFF0000) >> 16);
if(fmap_readn(map, &i32, *pos, sizeof(uint32_t)) != sizeof(uint32_t))
return -1;
(*pos) += sizeof(uint32_t);
*length = (int32_t)host32(i32);
cli_dbgmsg("message tag 0x%x, type 0x%x, length %d\n",
*tag, *type, (int)*length);
return 1;
}