/*
* Copyright (C) 2013-2019 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2011-2013 Sourcefire, Inc.
*
* The code is based on Flasm, command line assembler & disassembler of Flash
* ActionScript bytecode Copyright (c) 2001 Opaque Industries, (c) 2002-2007
* Igor Kogan, (c) 2005 Wang Zhen. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice, this list
* of conditions and the following disclaimer.
* - Redistributions in binary form must reproduce the above copyright notice, this
* list of conditions and the following disclaimer in the documentation and/or other
* materials provided with the distribution.
* - Neither the name of the Opaque Industries nor the names of its contributors may
* be used to endorse or promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
* SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
* BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
* WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/stat.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <time.h>
#include <zlib.h>
#include "swf.h"
#include "clamav.h"
#include "scanners.h"
#include "lzma_iface.h"
#define EC16(v) le16_to_host(v)
#define EC32(v) le32_to_host(v)
#define INITBITS \
{ \
if(fmap_readn(map, &get_c, offset, sizeof(get_c)) == sizeof(get_c)) { \
bitpos = 8; \
bitbuf = (unsigned int) get_c; \
offset += sizeof(get_c); \
} else { \
cli_warnmsg("cli_scanswf: INITBITS: Can't read file or file truncated\n"); \
return CL_EFORMAT; \
} \
}
#define GETBITS(v, n) \
{ \
getbits_n = n; \
bits = 0; \
while(getbits_n > bitpos) { \
getbits_n -= bitpos; \
bits |= bitbuf << getbits_n; \
if(fmap_readn(map, &get_c, offset, sizeof(get_c)) == sizeof(get_c)) { \
bitbuf = (unsigned int) get_c; \
bitpos = 8; \
offset += sizeof(get_c); \
} else { \
cli_warnmsg("cli_scanswf: GETBITS: Can't read file or file truncated\n"); \
return CL_EFORMAT; \
} \
} \
bitpos -= getbits_n; \
bits |= bitbuf >> bitpos; \
bitbuf &= 0xff >> (8 - bitpos); \
v = bits & 0xffff; \
}
#define GETWORD(v) \
{ \
if(fmap_readn(map, &get_c, offset, sizeof(get_c)) == sizeof(get_c)) { \
getword_1 = (unsigned int) get_c; \
offset += sizeof(get_c); \
} else { \
cli_warnmsg("cli_scanswf: GETWORD: Can't read file or file truncated\n"); \
return CL_EFORMAT; \
} \
if(fmap_readn(map, &get_c, offset, sizeof(get_c)) == sizeof(get_c)) { \
getword_2 = (unsigned int) get_c; \
offset += sizeof(get_c); \
} else { \
cli_warnmsg("cli_scanswf: GETWORD: Can't read file or file truncated\n"); \
return CL_EFORMAT; \
} \
v = (uint16_t)(getword_1 & 0xff) | ((getword_2 & 0xff) << 8); \
}
#define GETDWORD(v) \
{ \
GETWORD(getdword_1); \
GETWORD(getdword_2); \
v = (uint32_t)(getdword_1 | (getdword_2 << 16)); \
}
struct swf_file_hdr {
char signature[3];
uint8_t version;
uint32_t filesize;
};
static int scanzws(cli_ctx *ctx, struct swf_file_hdr *hdr)
{
struct CLI_LZMA lz;
unsigned char inbuff[FILEBUFF], outbuff[FILEBUFF];
fmap_t *map = *ctx->fmap;
/* strip off header */
off_t offset = 8;
uint32_t d_insize;
size_t outsize = 8;
int ret, lret, count;
char *tmpname;
int fd;
if((ret = cli_gentempfd(ctx->engine->tmpdir, &tmpname, &fd)) != CL_SUCCESS) {
cli_errmsg("scanzws: Can't generate temporary file\n");
return ret;
}
hdr->signature[0] = 'F';
if(cli_writen(fd, hdr, sizeof(struct swf_file_hdr)) != sizeof(struct swf_file_hdr)) {
cli_errmsg("scanzws: Can't write to file %s\n", tmpname);
close(fd);
if(cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EWRITE;
}
/* read 4 bytes (for compressed 32-bit filesize) [not used for LZMA] */
if (fmap_readn(map, &d_insize, offset, sizeof(d_insize)) != sizeof(d_insize)) {
cli_errmsg("scanzws: Error reading SWF file\n");
close(fd);
if (cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EREAD;
}
offset += sizeof(d_insize);
/* check if declared input size matches actual output size */
/* map->len = header (8 bytes) + d_insize (4 bytes) + flags (5 bytes) + compressed stream */
if (d_insize != (map->len - 17)) {
cli_warnmsg("SWF: declared input length != compressed stream size, %u != %llu\n",
d_insize, (long long unsigned)(map->len - 17));
} else {
cli_dbgmsg("SWF: declared input length == compressed stream size, %u == %llu\n",
d_insize, (long long unsigned)(map->len - 17));
}
/* first buffer required for initializing LZMA */
ret = fmap_readn(map, inbuff, offset, FILEBUFF);
if (ret < 0) {
cli_errmsg("scanzws: Error reading SWF file\n");
close(fd);
if (cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EUNPACK;
}
/* nothing written, likely truncated */
if (!ret) {
cli_errmsg("scanzws: possibly truncated file\n");
close(fd);
if (cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EFORMAT;
}
offset += ret;
memset(&lz, 0, sizeof(lz));
lz.next_in = inbuff;
lz.next_out = outbuff;
lz.avail_in = ret;
lz.avail_out = FILEBUFF;
lret = cli_LzmaInit(&lz, hdr->filesize);
if (lret != LZMA_RESULT_OK) {
cli_errmsg("scanzws: LzmaInit() failed\n");
close(fd);
if (cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EUNPACK;
}
while (lret == LZMA_RESULT_OK) {
if (lz.avail_in == 0) {
lz.next_in = inbuff;
ret = fmap_readn(map, inbuff, offset, FILEBUFF);
if (ret < 0) {
cli_errmsg("scanzws: Error reading SWF file\n");
cli_LzmaShutdown(&lz);
close(fd);
if (cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EUNPACK;
}
if (!ret)
break;
lz.avail_in = ret;
offset += ret;
}
lret = cli_LzmaDecode(&lz);
count = FILEBUFF - lz.avail_out;
if (count) {
if (cli_checklimits("SWF", ctx, outsize + count, 0, 0) != CL_SUCCESS)
break;
if (cli_writen(fd, outbuff, count) != count) {
cli_errmsg("scanzws: Can't write to file %s\n", tmpname);
cli_LzmaShutdown(&lz);
close(fd);
if (cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EWRITE;
}
outsize += count;
}
lz.next_out = outbuff;
lz.avail_out = FILEBUFF;
}
cli_LzmaShutdown(&lz);
if (lret != LZMA_STREAM_END && lret != LZMA_RESULT_OK) {
/* outsize starts at 8, therefore, if its still 8, nothing was decompressed */
if (outsize == 8) {
cli_infomsg(ctx, "scanzws: Error decompressing SWF file. No data decompressed.\n");
close(fd);
if (cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EUNPACK;
}
cli_infomsg(ctx, "scanzws: Error decompressing SWF file. Scanning what was decompressed.\n");
}
cli_dbgmsg("SWF: Decompressed[LZMA] to %s, size %llu\n", tmpname, (long long unsigned)outsize);
/* check if declared output size matches actual output size */
if (hdr->filesize != outsize) {
cli_warnmsg("SWF: declared output length != inflated stream size, %u != %llu\n",
hdr->filesize, (long long unsigned)outsize);
} else {
cli_dbgmsg("SWF: declared output length == inflated stream size, %u == %llu\n",
hdr->filesize, (long long unsigned)outsize);
}
ret = cli_magic_scandesc(fd, tmpname, ctx);
close(fd);
if (!(ctx->engine->keeptmp)) {
if (cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
}
free(tmpname);
return ret;
}
static int scancws(cli_ctx *ctx, struct swf_file_hdr *hdr)
{
z_stream stream;
char inbuff[FILEBUFF], outbuff[FILEBUFF];
fmap_t *map = *ctx->fmap;
int offset = 8, ret, zret, outsize = 8, count, zend;
char *tmpname;
int fd;
if((ret = cli_gentempfd(ctx->engine->tmpdir, &tmpname, &fd)) != CL_SUCCESS) {
cli_errmsg("scancws: Can't generate temporary file\n");
return ret;
}
hdr->signature[0] = 'F';
if(cli_writen(fd, hdr, sizeof(struct swf_file_hdr)) != sizeof(struct swf_file_hdr)) {
cli_errmsg("scancws: Can't write to file %s\n", tmpname);
close(fd);
if(cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EWRITE;
}
stream.avail_in = 0;
stream.next_in = (Bytef *)inbuff;
stream.next_out = (Bytef *)outbuff;
stream.zalloc = (alloc_func) NULL;
stream.zfree = (free_func) NULL;
stream.opaque = (voidpf) 0;
stream.avail_out = FILEBUFF;
zret = inflateInit(&stream);
if(zret != Z_OK) {
cli_errmsg("scancws: inflateInit() failed\n");
close(fd);
if(cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EUNPACK;
}
do {
if(stream.avail_in == 0) {
stream.next_in = (Bytef *)inbuff;
ret = fmap_readn(map, inbuff, offset, FILEBUFF);
if(ret < 0) {
cli_errmsg("scancws: Error reading SWF file\n");
close(fd);
inflateEnd(&stream);
if(cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EUNPACK;
}
if(!ret)
break;
stream.avail_in = ret;
offset += ret;
}
zret = inflate(&stream, Z_SYNC_FLUSH);
count = FILEBUFF - stream.avail_out;
if(count) {
if(cli_checklimits("SWF", ctx, outsize + count, 0, 0) != CL_SUCCESS)
break;
if(cli_writen(fd, outbuff, count) != count) {
cli_errmsg("scancws: Can't write to file %s\n", tmpname);
inflateEnd(&stream);
close(fd);
if(cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EWRITE;
}
outsize += count;
}
stream.next_out = (Bytef *)outbuff;
stream.avail_out = FILEBUFF;
} while(zret == Z_OK);
zend = inflateEnd(&stream);
if((zret != Z_STREAM_END && zret != Z_OK) || zend != Z_OK) {
/*
* outsize is initialized to 8, it being 8 here means that we couldn't even read a single byte.
* If outsize > 8, then we have data. Let's scan what we have.
*/
if (outsize == 8) {
cli_infomsg(ctx, "scancws: Error decompressing SWF file. No data decompressed.\n");
close(fd);
if(cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
free(tmpname);
return CL_EUNPACK;
}
cli_infomsg(ctx, "scancws: Error decompressing SWF file. Scanning what was decompressed.\n");
}
cli_dbgmsg("SWF: Decompressed[zlib] to %s, size %d\n", tmpname, outsize);
/* check if declared output size matches actual output size */
if (hdr->filesize != outsize) {
cli_warnmsg("SWF: declared output length != inflated stream size, %u != %llu\n",
hdr->filesize, (long long unsigned)outsize);
} else {
cli_dbgmsg("SWF: declared output length == inflated stream size, %u == %llu\n",
hdr->filesize, (long long unsigned)outsize);
}
ret = cli_magic_scandesc(fd, tmpname, ctx);
close(fd);
if(!ctx->engine->keeptmp) {
if(cli_unlink(tmpname)) {
free(tmpname);
return CL_EUNLINK;
}
}
free(tmpname);
return ret;
}
static const char *tagname(tag_id id)
{
unsigned int i;
for(i = 0; tag_names[i].name; i++)
if(tag_names[i].id == id)
return tag_names[i].name;
return NULL;
}
int cli_scanswf(cli_ctx *ctx)
{
struct swf_file_hdr file_hdr;
fmap_t *map = *ctx->fmap;
unsigned int bitpos, bitbuf, getbits_n, nbits, getword_1, getword_2, getdword_1, getdword_2;
const char *pt;
unsigned char get_c;
size_t offset = 0;
unsigned int val, foo, tag_hdr, tag_type, tag_len;
unsigned long int bits;
cli_dbgmsg("in cli_scanswf()\n");
if(fmap_readn(map, &file_hdr, offset, sizeof(file_hdr)) != sizeof(file_hdr)) {
cli_dbgmsg("SWF: Can't read file header\n");
return CL_CLEAN;
}
offset += sizeof(file_hdr);
/*
** SWF stores the integer bytes with the least significate byte first
*/
file_hdr.filesize = le32_to_host (file_hdr.filesize);
cli_dbgmsg("SWF: Version: %u\n", file_hdr.version);
cli_dbgmsg("SWF: File size: %u\n", file_hdr.filesize);
if(!strncmp(file_hdr.signature, "CWS", 3)) {
cli_dbgmsg("SWF: zlib compressed file\n");
return scancws(ctx, &file_hdr);
} else if(!strncmp(file_hdr.signature, "ZWS", 3)) {
cli_dbgmsg("SWF: LZMA compressed file\n");
return scanzws(ctx, &file_hdr);
} else if(!strncmp(file_hdr.signature, "FWS", 3)) {
cli_dbgmsg("SWF: Uncompressed file\n");
} else {
cli_dbgmsg("SWF: Not a SWF file\n");
return CL_CLEAN;
}
INITBITS;
GETBITS(nbits, 5);
cli_dbgmsg("SWF: FrameSize RECT size bits: %u\n", nbits);
{
uint32_t xMin = 0, xMax = 0, yMin = 0, yMax = 0;
GETBITS(xMin, nbits); /* Should be zero */
GETBITS(xMax, nbits);
GETBITS(yMin, nbits); /* Should be zero */
GETBITS(yMax, nbits);
cli_dbgmsg("SWF: FrameSize xMin %u xMax %u yMin %u yMax %u\n", xMin, xMax, yMin, yMax);
}
GETWORD(foo);
GETWORD(val);
cli_dbgmsg("SWF: Frames total: %d\n", val);
/* Skip Flash tag walk unless debug mode */
if(!cli_debug_flag) {
return CL_CLEAN;
}
while(offset < map->len) {
GETWORD(tag_hdr);
tag_type = tag_hdr >> 6;
if(tag_type == 0)
break;
tag_len = tag_hdr & 0x3f;
if(tag_len == 0x3f)
GETDWORD(tag_len);
pt = tagname(tag_type);
cli_dbgmsg("SWF: %s\n", pt ? pt : "UNKNOWN TAG");
cli_dbgmsg("SWF: Tag length: %u\n", tag_len);
if (tag_len > map->len) {
cli_dbgmsg("SWF: Invalid tag length.\n");
return CL_EFORMAT;
}
if ((offset + tag_len) < offset) {
cli_warnmsg("SWF: Tag length too large.\n");
break;
}
if(!pt) {
offset += tag_len;
continue;
}
switch(tag_type) {
case TAG_SCRIPTLIMITS: {
unsigned int recursion, timeout;
GETWORD(recursion);
GETWORD(timeout);
cli_dbgmsg("SWF: scriptLimits recursion %u timeout %u\n", recursion, timeout);
break;
}
case TAG_FILEATTRIBUTES:
GETDWORD(val);
cli_dbgmsg("SWF: File attributes:\n");
if(val & SWF_ATTR_USENETWORK)
cli_dbgmsg(" * Use network\n");
if(val & SWF_ATTR_RELATIVEURLS)
cli_dbgmsg(" * Relative URLs\n");
if(val & SWF_ATTR_SUPPRESSCROSSDOMAINCACHE)
cli_dbgmsg(" * Suppress cross domain cache\n");
if(val & SWF_ATTR_ACTIONSCRIPT3)
cli_dbgmsg(" * ActionScript 3.0\n");
if(val & SWF_ATTR_HASMETADATA)
cli_dbgmsg(" * Has metadata\n");
if(val & SWF_ATTR_USEDIRECTBLIT)
cli_dbgmsg(" * Use hardware acceleration\n");
if(val & SWF_ATTR_USEGPU)
cli_dbgmsg(" * Use GPU\n");
break;
default:
offset += tag_len;
continue;
}
}
return CL_CLEAN;
}