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/* Copyright (C) 2020-2022 Open Information Security Foundation
*
* You can copy, redistribute or modify this Program 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
* version 2 along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
/**
* \file detect-asn1.c
*
* Implements "asn1" keyword
*/
#include "suricata-common.h"
#include "decode.h"
#include "rust.h"
#include "detect.h"
#include "detect-parse.h"
#include "flow.h"
#include "detect-asn1.h"
#include "util-unittest.h"
#include "util-unittest-helper.h"
#include "util-byte.h"
#include "util-debug.h"
static int DetectAsn1Match(DetectEngineThreadCtx *, Packet *,
const Signature *, const SigMatchCtx *);
static int DetectAsn1Setup (DetectEngineCtx *, Signature *, const char *);
#ifdef UNITTESTS
static void DetectAsn1RegisterTests(void);
#endif
static void DetectAsn1Free(DetectEngineCtx *, void *);
/**
* \brief Registration function for asn1
*/
void DetectAsn1Register(void)
{
sigmatch_table[DETECT_ASN1].name = "asn1";
sigmatch_table[DETECT_ASN1].Match = DetectAsn1Match;
sigmatch_table[DETECT_ASN1].Setup = DetectAsn1Setup;
sigmatch_table[DETECT_ASN1].Free = DetectAsn1Free;
#ifdef UNITTESTS
sigmatch_table[DETECT_ASN1].RegisterTests = DetectAsn1RegisterTests;
#endif
}
/**
* \brief This function will decode the asn1 data and inspect the resulting
* nodes to detect if any of the specified checks match this data
*
* \param det_ctx pointer to the detect engine thread context
* \param p pointer to the current packet
* \param s pointer to the signature
* \param ctx pointer to the sigmatch that we will cast into `DetectAsn1Data`
*
* \retval 1 match
* \retval 0 no match
*/
static int DetectAsn1Match(DetectEngineThreadCtx *det_ctx, Packet *p,
const Signature *s, const SigMatchCtx *ctx)
{
uint8_t ret = 0;
if (p->payload_len == 0) {
/* No error, parser done, no data in bounds to decode */
return 0;
}
const DetectAsn1Data *ad = (const DetectAsn1Data *)ctx;
Asn1 *asn1 = rs_asn1_decode(p->payload, p->payload_len, det_ctx->buffer_offset, ad);
ret = rs_asn1_checks(asn1, ad);
rs_asn1_free(asn1);
return ret;
}
/**
* \brief This function is used to parse asn1 options passed via asn1: keyword
*
* \param asn1str pointer to the user provided asn1 options
*
* \retval pointer to `DetectAsn1Data` on success
* \retval NULL on failure
*/
static DetectAsn1Data *DetectAsn1Parse(const char *asn1str)
{
DetectAsn1Data *ad = rs_detect_asn1_parse(asn1str);
if (ad == NULL) {
SCLogError("Malformed asn1 argument: %s", asn1str);
}
return ad;
}
/**
* \brief this function is used to add the parsed asn1 data into
* the current signature
*
* \param de_ctx pointer to the detection engine context
* \param s pointer to the current signature
* \param asn1str pointer to the user provided asn1 options
*
* \retval 0 on success
* \retval -1 on failure
*/
static int DetectAsn1Setup(DetectEngineCtx *de_ctx, Signature *s, const char *asn1str)
{
DetectAsn1Data *ad = DetectAsn1Parse(asn1str);
if (ad == NULL)
return -1;
/* Okay so far so good, lets get this into a SigMatch
* and put it in the Signature. */
SigMatch *sm = SigMatchAlloc();
if (sm == NULL) {
DetectAsn1Free(de_ctx, ad);
return -1;
}
sm->type = DETECT_ASN1;
sm->ctx = (SigMatchCtx *)ad;
SigMatchAppendSMToList(s, sm, DETECT_SM_LIST_MATCH);
return 0;
}
/**
* \brief this function will free memory associated with `DetectAsn1Data`
*
* \param de_ctx pointer to the detection engine context
* \param ptr point to `DetectAsn1Data`
*/
static void DetectAsn1Free(DetectEngineCtx *de_ctx, void *ptr)
{
DetectAsn1Data *ad = (DetectAsn1Data *)ptr;
rs_detect_asn1_free(ad);
}
#ifdef UNITTESTS
/**
* \test DetectAsn1TestReal01 Ensure that all works together
*/
static int DetectAsn1TestReal01(void)
{
uint8_t *buf = (uint8_t *) "\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01"
"P""\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111"
"\x31\x1F\x61\x11\x1A\x05""Susan""\x1A\x01""B""\x1A\x05"
"Jones""\xA0\x0A\x43\x08""19590717"
"\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01""P"
"\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111""\x31\x1F"
"\x61\x11\x1A\x05""Pablo""\x1A\x01""B""\x1A\x05""Jones"
"\xA0\x0A\x43\x08""19590717";
uint16_t buflen = strlen((char *)buf) - 1;
/* Check the start with AA (this is to test the relative_offset keyword) */
uint8_t *buf2 = (uint8_t *) "AA\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01"
"P""\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111"
"\x31\x1F\x61\x11\x1A\x05""Susan""\x1A\x01""B""\x1A\x05"
"Jones""\xA0\x0A\x43\x08""19590717"
"\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01""P"
"\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111""\x31\x1F"
"\x61\x11\x1A\x05""Susan""\x1A\x01""B""\x1A\x05""Jones"
"\xA0\x0A\x43\x08""19590717";
uint16_t buflen2 = strlen((char *)buf2) - 1;
Packet *p[2];
p[0] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);
FAIL_IF_NULL(p[0]);
p[1] = UTHBuildPacket((uint8_t *)buf2, buflen2, IPPROTO_TCP);
FAIL_IF_NULL(p[1]);
const char *sigs[3];
sigs[0]= "alert ip any any -> any any (msg:\"Testing id 1\"; "
"content:\"Pablo\"; asn1:absolute_offset 0, "
"oversize_length 130; sid:1;)";
sigs[1]= "alert ip any any -> any any (msg:\"Testing id 2\"; "
"content:\"AA\"; asn1:relative_offset 0, "
"oversize_length 130; sid:2;)";
sigs[2]= "alert ip any any -> any any (msg:\"Testing id 3\"; "
"content:\"lalala\"; asn1: oversize_length 2000; sid:3;)";
uint32_t sid[3] = {1, 2, 3};
uint32_t results[2][3] = {
/* packet 0 match sid 1 */
{1, 0, 0},
/* packet 1 match sid 2 */
{0, 1, 0}};
/* None of the packets should match sid 3 */
FAIL_IF_NOT(UTHGenericTest(p, 2, sigs, sid, (uint32_t *)results, 3) == 1);
UTHFreePackets(p, 2);
PASS;
}
/**
* \test DetectAsn1TestReal02 Ensure that all works together
*/
static int DetectAsn1TestReal02(void)
{
int result = 0;
uint8_t *buf = (uint8_t *) "\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01"
"P""\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111"
"\x31\x1F\x61\x11\x1A\x05""Susan""\x1A\x01""B""\x1A\x05"
"Jones""\xA0\x0A\x43\x08""19590717"
"\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01""P"
"\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111""\x31\x1F"
"\x61\x11\x1A\x05""Pablo""\x1A\x01""B""\x1A\x05""Jones"
"\xA0\x0A\x43\x08""19590717";
uint16_t buflen = strlen((char *)buf) - 1;
/* Check the start with AA (this is to test the relative_offset keyword) */
uint8_t *buf2 = (uint8_t *) "AA\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01"
"P""\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111"
"\x31\x1F\x61\x11\x1A\x05""Susan""\x1A\x01""B""\x1A\x05"
"Jones""\xA0\x0A\x43\x08""19590717"
"\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01""P"
"\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111""\x31\x1F"
"\x61\x11\x1A\x05""Susan""\x1A\x01""B""\x1A\x05""Jones"
"\xA0\x0A\x43\x08""19590717";
uint16_t buflen2 = strlen((char *)buf2) - 1;
Packet *p[2];
p[0] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);
p[1] = UTHBuildPacket((uint8_t *)buf2, buflen2, IPPROTO_TCP);
if (p[0] == NULL || p[1] == NULL)
goto end;
const char *sigs[3];
sigs[0]= "alert ip any any -> any any (msg:\"Testing id 1\"; "
"content:\"Pablo\"; asn1:absolute_offset 0, "
"oversize_length 140; sid:1;)";
sigs[1]= "alert ip any any -> any any (msg:\"Testing id 2\"; "
"content:\"AA\"; asn1:relative_offset 0, "
"oversize_length 140; sid:2;)";
sigs[2]= "alert ip any any -> any any (msg:\"Testing id 3\"; "
"content:\"lalala\"; asn1: oversize_length 2000; sid:3;)";
uint32_t sid[3] = {1, 2, 3};
uint32_t results[2][3] = {
{0, 0, 0},
{0, 0, 0}};
/* None of the packets should match */
result = UTHGenericTest(p, 2, sigs, sid, (uint32_t *) results, 3);
UTHFreePackets(p, 2);
end:
return result;
}
/**
* \test DetectAsn1TestReal03 Ensure that all works together
*/
static int DetectAsn1TestReal03(void)
{
int result = 0;
uint8_t buf[261] = "";
/* universal class, primitive type, tag_num = 9 (Data type Real) */
buf[0] = '\x09';
/* length, definite form, 2 octets */
buf[1] = '\x82';
/* length is the sum of the following octets (257): */
buf[2] = '\x01';
buf[3] = '\x01';
/* Fill the content of the number */
uint16_t i = 4;
for (; i < 257;i++)
buf[i] = '\x05';
uint16_t buflen = 261;
/* Check the start with AA (this is to test the relative_offset keyword) */
uint8_t *buf2 = (uint8_t *) "AA\x03\x01\xFF";
uint16_t buflen2 = 5;
Packet *p[2] = { NULL, NULL };
p[0] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);
p[1] = UTHBuildPacket((uint8_t *)buf2, buflen2, IPPROTO_TCP);
if (p[0] == NULL || p[1] == NULL)
goto end;
const char *sigs[3];
/* This should match the first packet */
sigs[0]= "alert ip any any -> any any (msg:\"Testing id 1\"; "
"asn1:absolute_offset 0, double_overflow; sid:1;)";
/* This should match the second packet */
sigs[1]= "alert ip any any -> any any (msg:\"Testing id 2\"; "
"asn1:relative_offset 2, bitstring_overflow,"
"oversize_length 140; sid:2;)";
/* This should match no packet */
sigs[2]= "alert ip any any -> any any (msg:\"Testing id 3\"; "
"asn1: oversize_length 2000; sid:3;)";
uint32_t sid[3] = {1, 2, 3};
uint32_t results[2][3] = {{1, 0, 0},
{0, 1, 0}};
result = UTHGenericTest(p, 2, sigs, sid, (uint32_t *) results, 3);
UTHFreePackets(p, 2);
end:
return result;
}
/**
* \test DetectAsn1TestReal04 like the real test 02, but modified the
* relative offset to check negative offset values, in this case
* start decoding from -7 bytes respect the content match "John"
*/
static int DetectAsn1TestReal04(void)
{
int result = 0;
uint8_t *buf = (uint8_t *) "\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01"
"P""\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111"
"\x31\x1F\x61\x11\x1A\x05""Susan""\x1A\x01""B""\x1A\x05"
"Jones""\xA0\x0A\x43\x08""19590717"
"\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01""P"
"\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111""\x31\x1F"
"\x61\x11\x1A\x05""Pablo""\x1A\x01""B""\x1A\x05""Jones"
"\xA0\x0A\x43\x08""19590717";
uint16_t buflen = strlen((char *)buf) - 1;
/* Check the start with AA (this is to test the relative_offset keyword) */
uint8_t *buf2 = (uint8_t *) "AA\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01"
"P""\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111"
"\x31\x1F\x61\x11\x1A\x05""Susan""\x1A\x01""B""\x1A\x05"
"Jones""\xA0\x0A\x43\x08""19590717"
"\x60\x81\x85\x61\x10\x1A\x04""John""\x1A\x01""P"
"\x1A\x05""Smith""\xA0\x0A\x1A\x08""Director"
"\x42\x01\x33\xA1\x0A\x43\x08""19710917"
"\xA2\x12\x61\x10\x1A\x04""Mary""\x1A\x01""T""\x1A\x05"
"Smith""\xA3\x42\x31\x1F\x61\x11\x1A\x05""Ralph""\x1A\x01"
"T""\x1A\x05""Smith""\xA0\x0A\x43\x08""19571111""\x31\x1F"
"\x61\x11\x1A\x05""Susan""\x1A\x01""B""\x1A\x05""Jones"
"\xA0\x0A\x43\x08""19590717";
uint16_t buflen2 = strlen((char *)buf2) - 1;
Packet *p[2];
p[0] = UTHBuildPacket((uint8_t *)buf, buflen, IPPROTO_TCP);
p[1] = UTHBuildPacket((uint8_t *)buf2, buflen2, IPPROTO_TCP);
if (p[0] == NULL || p[1] == NULL)
goto end;
const char *sigs[3];
sigs[0]= "alert ip any any -> any any (msg:\"Testing id 1\"; "
"content:\"Pablo\"; asn1:absolute_offset 0, "
"oversize_length 140; sid:1;)";
sigs[1]= "alert ip any any -> any any (msg:\"Testing id 2\"; "
"content:\"John\"; asn1:relative_offset -11, "
"oversize_length 140; sid:2;)";
sigs[2]= "alert ip any any -> any any (msg:\"Testing id 3\"; "
"content:\"lalala\"; asn1: oversize_length 2000; sid:3;)";
uint32_t sid[3] = {1, 2, 3};
uint32_t results[2][3] = {
{0, 0, 0},
{0, 0, 0}};
/* None of the packets should match */
result = UTHGenericTest(p, 2, sigs, sid, (uint32_t *) results, 3);
UTHFreePackets(p, 2);
end:
return result;
}
/**
* \brief this function registers unit tests for DetectAsn1
*/
static void DetectAsn1RegisterTests(void)
{
UtRegisterTest("DetectAsn1TestReal01", DetectAsn1TestReal01);
UtRegisterTest("DetectAsn1TestReal02", DetectAsn1TestReal02);
UtRegisterTest("DetectAsn1TestReal03", DetectAsn1TestReal03);
UtRegisterTest("DetectAsn1TestReal04", DetectAsn1TestReal04);
}
#endif /* UNITTESTS */
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