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detect/xbits: parse keywords w strtok_r

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Ticket: 4820

Forward ported by Victor Julien from
2c5eead479 ("detect/xbits: parse keywords w strtok_r")

(cherry picked from commit 926ef4c49a)
pull/14575/head
Shivani Bhardwaj 4 years ago committed by Victor Julien
parent 91c07f10bd
commit 5eb629cbd6
1 changed files with 262 additions and 119 deletions
Show Stats Download Patch File Download Diff File

381
src/detect-xbits.c
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@ -58,9 +58,6 @@
xbits:set,bitname,track ip_pair,expire 60
*/
#define PARSE_REGEX "^([a-z]+)" "(?:,\\s*([^,]+))?" "(?:,\\s*(?:track\\s+([^,]+)))" "(?:,\\s*(?:expire\\s+([^,]+)))?"
static DetectParseRegex parse_regex;
static int DetectXbitTxMatch(DetectEngineThreadCtx *det_ctx, Flow *f, uint8_t flags, void *state,
void *txv, const Signature *s, const SigMatchCtx *ctx);
static int DetectXbitMatch (DetectEngineThreadCtx *, Packet *, const Signature *, const SigMatchCtx *);
@ -84,8 +81,6 @@ void DetectXbitsRegister (void)
#endif
/* this is compatible to ip-only signatures */
sigmatch_table[DETECT_XBITS].flags |= (SIGMATCH_IPONLY_COMPAT | SIGMATCH_SUPPORT_FIREWALL);
DetectSetupParseRegexes(PARSE_REGEX, &parse_regex);
}
static int DetectIPPairbitMatchToggle (Packet *p, const DetectXbitsData *fd)
@ -239,136 +234,116 @@ static int DetectXbitTxMatch(DetectEngineThreadCtx *det_ctx, Flow *f, uint8_t fl
static int DetectXbitParse(DetectEngineCtx *de_ctx,
const char *rawstr, DetectXbitsData **cdout)
{
DetectXbitsData *cd = NULL;
uint8_t fb_cmd = 0;
uint8_t hb_dir = 0;
size_t pcre2len;
char fb_cmd_str[16] = "", fb_name[256] = "";
char hb_dir_str[16] = "";
bool cmd_set = false;
bool name_set = false;
bool track_set = false;
bool expire_set = false;
uint8_t cmd = 0;
uint8_t track = 0;
enum VarTypes var_type = VAR_TYPE_NOT_SET;
uint32_t expire = DETECT_XBITS_EXPIRE_DEFAULT;
pcre2_match_data *match = NULL;
int ret = DetectParsePcreExec(&parse_regex, &match, rawstr, 0, 0);
if (ret != 2 && ret != 3 && ret != 4 && ret != 5) {
SCLogError("\"%s\" is not a valid setting for xbits.", rawstr);
if (match) {
pcre2_match_data_free(match);
DetectXbitsData *cd = NULL;
char name[256] = "";
char copy[strlen(rawstr) + 1];
strlcpy(copy, rawstr, sizeof(copy));
char *context = NULL;
char *token = strtok_r(copy, ",", &context);
while (token != NULL) {
while (*token != '\0' && isblank(*token)) {
token++;
}
return -1;
}
SCLogDebug("ret %d, %s", ret, rawstr);
pcre2len = sizeof(fb_cmd_str);
int res = pcre2_substring_copy_bynumber(match, 1, (PCRE2_UCHAR8 *)fb_cmd_str, &pcre2len);
if (res < 0) {
SCLogError("pcre2_substring_copy_bynumber failed");
pcre2_match_data_free(match);
return -1;
}
if (ret >= 3) {
pcre2len = sizeof(fb_name);
res = pcre2_substring_copy_bynumber(match, 2, (PCRE2_UCHAR8 *)fb_name, &pcre2len);
if (res < 0) {
SCLogError("pcre2_substring_copy_bynumber failed");
pcre2_match_data_free(match);
return -1;
char *val = strchr(token, ' ');
if (val != NULL) {
*val++ = '\0';
while (*val != '\0' && isblank(*val)) {
val++;
}
} else {
SCLogDebug("val %s", token);
}
if (strlen(token) == 0) {
goto next;
}
if (strcmp(token, "noalert") == 0 && !cmd_set) {
if (strtok_r(NULL, ",", &context) != NULL) {
return -1;
}
if (val && strlen(val) != 0) {
return -1;
}
*cdout = NULL;
return 0;
}
if (ret >= 4) {
pcre2len = sizeof(hb_dir_str);
res = pcre2_substring_copy_bynumber(match, 3, (PCRE2_UCHAR8 *)hb_dir_str, &pcre2len);
if (res < 0) {
SCLogError("pcre2_substring_copy_bynumber failed");
pcre2_match_data_free(match);
if (!cmd_set) {
if (val && strlen(val) != 0) {
return -1;
}
if (strcmp(token, "set") == 0) {
cmd = DETECT_XBITS_CMD_SET;
} else if (strcmp(token, "isset") == 0) {
cmd = DETECT_XBITS_CMD_ISSET;
} else if (strcmp(token, "unset") == 0) {
cmd = DETECT_XBITS_CMD_UNSET;
} else if (strcmp(token, "isnotset") == 0) {
cmd = DETECT_XBITS_CMD_ISNOTSET;
} else if (strcmp(token, "toggle") == 0) {
cmd = DETECT_XBITS_CMD_TOGGLE;
} else {
SCLogError("Invalid xbits cmd: %s", token);
return -1;
}
cmd_set = true;
} else if (!name_set) {
if (val && strlen(val) != 0) {
return -1;
}
SCLogDebug("hb_dir_str %s", hb_dir_str);
if (strlen(hb_dir_str) > 0) {
if (strcmp(hb_dir_str, "ip_src") == 0) {
hb_dir = DETECT_XBITS_TRACK_IPSRC;
strlcpy(name, token, sizeof(name));
name_set = true;
} else if (!track_set || !expire_set) {
if (val == NULL) {
return -1;
}
if (strcmp(token, "track") == 0) {
if (track_set) {
return -1;
}
if (strcmp(val, "ip_src") == 0) {
track = DETECT_XBITS_TRACK_IPSRC;
var_type = VAR_TYPE_HOST_BIT;
} else if (strcmp(hb_dir_str, "ip_dst") == 0) {
hb_dir = DETECT_XBITS_TRACK_IPDST;
} else if (strcmp(val, "ip_dst") == 0) {
track = DETECT_XBITS_TRACK_IPDST;
var_type = VAR_TYPE_HOST_BIT;
} else if (strcmp(hb_dir_str, "ip_pair") == 0) {
hb_dir = DETECT_XBITS_TRACK_IPPAIR;
} else if (strcmp(val, "ip_pair") == 0) {
track = DETECT_XBITS_TRACK_IPPAIR;
var_type = VAR_TYPE_IPPAIR_BIT;
} else if (strcmp(hb_dir_str, "tx") == 0) {
hb_dir = DETECT_XBITS_TRACK_TX;
} else if (strcmp(val, "tx") == 0) {
track = DETECT_XBITS_TRACK_TX;
var_type = VAR_TYPE_TX_BIT;
} else {
// TODO
pcre2_match_data_free(match);
return -1;
}
}
if (ret >= 5) {
char expire_str[16] = "";
pcre2len = sizeof(expire_str);
res = pcre2_substring_copy_bynumber(
match, 4, (PCRE2_UCHAR8 *)expire_str, &pcre2len);
if (res < 0) {
SCLogError("pcre2_substring_copy_bynumber failed");
pcre2_match_data_free(match);
SCLogError("Invalid xbits tracker: %s", val);
return -1;
}
SCLogDebug("expire_str %s", expire_str);
if (StringParseUint32(&expire, 10, 0, (const char *)expire_str) < 0) {
SCLogError("Invalid value for "
"expire: \"%s\"",
expire_str);
pcre2_match_data_free(match);
track_set = true;
} else if (strcmp(token, "expire") == 0) {
if (expire_set) {
return -1;
}
if (expire == 0) {
SCLogError("expire must be bigger than 0");
pcre2_match_data_free(match);
if ((StringParseUint32(&expire, 10, 0, val) < 0) || (expire == 0)) {
SCLogError("Invalid expire value: %s", val);
return -1;
}
SCLogDebug("expire %d", expire);
expire_set = true;
}
} else {
SCLogError("Invalid xbits keyword: %s", token);
return -1;
}
next:
token = strtok_r(NULL, ",", &context);
}
pcre2_match_data_free(match);
if (strcmp(fb_cmd_str,"noalert") == 0) {
fb_cmd = DETECT_XBITS_CMD_NOALERT;
} else if (strcmp(fb_cmd_str,"isset") == 0) {
fb_cmd = DETECT_XBITS_CMD_ISSET;
} else if (strcmp(fb_cmd_str,"isnotset") == 0) {
fb_cmd = DETECT_XBITS_CMD_ISNOTSET;
} else if (strcmp(fb_cmd_str,"set") == 0) {
fb_cmd = DETECT_XBITS_CMD_SET;
} else if (strcmp(fb_cmd_str,"unset") == 0) {
fb_cmd = DETECT_XBITS_CMD_UNSET;
} else if (strcmp(fb_cmd_str,"toggle") == 0) {
fb_cmd = DETECT_XBITS_CMD_TOGGLE;
} else {
SCLogError("xbits action \"%s\" is not supported.", fb_cmd_str);
return -1;
}
switch (fb_cmd) {
case DETECT_XBITS_CMD_NOALERT: {
if (strlen(fb_name) != 0)
return -1;
/* return ok, cd is NULL. Flag sig. */
*cdout = NULL;
return 0;
}
case DETECT_XBITS_CMD_ISNOTSET:
case DETECT_XBITS_CMD_ISSET:
case DETECT_XBITS_CMD_SET:
case DETECT_XBITS_CMD_UNSET:
case DETECT_XBITS_CMD_TOGGLE:
if (strlen(fb_name) == 0)
return -1;
break;
}
if (hb_dir == DETECT_XBITS_TRACK_TX) {
if (fb_cmd != DETECT_XBITS_CMD_ISSET && fb_cmd != DETECT_XBITS_CMD_SET) {
if (track == DETECT_XBITS_TRACK_TX) {
if (cmd != DETECT_XBITS_CMD_ISSET && cmd != DETECT_XBITS_CMD_SET) {
SCLogError("tx xbits only support set and isset");
return -1;
}
@ -378,14 +353,18 @@ static int DetectXbitParse(DetectEngineCtx *de_ctx,
if (unlikely(cd == NULL))
return -1;
cd->idx = VarNameStoreRegister(fb_name, var_type);
cd->cmd = fb_cmd;
cd->tracker = hb_dir;
uint32_t varname_id = VarNameStoreRegister(name, var_type);
if (unlikely(varname_id == 0)) {
SCFree(cd);
return -1;
}
cd->idx = varname_id;
cd->cmd = cmd;
cd->tracker = track;
cd->type = var_type;
cd->expire = expire;
SCLogDebug("idx %" PRIu32 ", cmd %s, name %s", cd->idx, fb_cmd_str,
strlen(fb_name) ? fb_name : "(none)");
SCLogDebug("idx %" PRIu32 ", cmd %d, name %s", cd->idx, cmd, strlen(name) ? name : "(none)");
*cdout = cd;
return 0;
@ -624,6 +603,164 @@ static int XBitsTestSig02(void)
PASS;
}
/* Test to demonstrate redmine bug 4820 */
static int XBitsTestSig03(void)
{
DetectEngineCtx *de_ctx = NULL;
XBitsTestSetup();
de_ctx = DetectEngineCtxInit();
FAIL_IF_NULL(de_ctx);
de_ctx->flags |= DE_QUIET;
Signature *s = DetectEngineAppendSig(
de_ctx, "alert http any any -> any any (msg:\"TEST - No Error\")\";\
flow:established,to_server; http.method; content:\"GET\"; \
xbits:set,ET.2020_8260.1,track ip_src,expire 10; sid:1;)");
FAIL_IF_NULL(s);
DetectEngineCtxFree(de_ctx);
XBitsTestShutdown();
PASS;
}
/* Test to demonstrate redmine bug 4820 */
static int XBitsTestSig04(void)
{
DetectEngineCtx *de_ctx = NULL;
XBitsTestSetup();
de_ctx = DetectEngineCtxInit();
FAIL_IF_NULL(de_ctx);
de_ctx->flags |= DE_QUIET;
Signature *s =
DetectEngineAppendSig(de_ctx, "alert http any any -> any any (msg:\"TEST - Error\")\"; \
flow:established,to_server; http.method; content:\"GET\"; \
xbits:set,ET.2020_8260.1,noalert,track ip_src,expire 10; sid:2;)");
FAIL_IF_NOT_NULL(s);
DetectEngineCtxFree(de_ctx);
XBitsTestShutdown();
PASS;
}
static int XBitsTestSig05(void)
{
DetectEngineCtx *de_ctx = NULL;
XBitsTestSetup();
de_ctx = DetectEngineCtxInit();
FAIL_IF_NULL(de_ctx);
de_ctx->flags |= DE_QUIET;
Signature *s = DetectEngineAppendSig(de_ctx,
"alert http any any -> any any (msg:\"ET EXPLOIT Possible Pulse Secure VPN RCE "
"Chain Stage 1 Inbound - Request Config Backup (CVE-2020-8260)\"; "
"flow:established,to_server; http.method; content:\"GET\"; http.uri; "
"content:\"/dana-admin/cached/config/config.cgi?type=system\"; fast_pattern; "
"xbits:set,ET.2020_8260.1,track ip_src,expire 10; xbits:noalert; "
"classtype:attempted-admin; sid:2033750; rev:1;");
FAIL_IF_NULL(s);
DetectEngineCtxFree(de_ctx);
XBitsTestShutdown();
PASS;
}
static int XBitsTestSig06(void)
{
DetectEngineCtx *de_ctx = NULL;
XBitsTestSetup();
de_ctx = DetectEngineCtxInit();
FAIL_IF_NULL(de_ctx);
de_ctx->flags |= DE_QUIET;
Signature *s = DetectEngineAppendSig(de_ctx,
"alert http any any -> any any (msg:\"ET EXPLOIT Possible Pulse Secure VPN RCE "
"Chain Stage 2 Inbound - Upload Malicious Config (CVE-2020-8260)\"; "
"flow:established,to_server; http.method; content:\"POST\"; http.uri; "
"content:\"/dana-admin/cached/config/import.cgi\"; "
"xbits:isset,ET.2020_8260.1,track ip_src,expire 10;"
"xbits:set,ET.2020_8260.2,track ip_src,expire 10; "
"classtype:attempted-admin; sid:2033751; rev:1;");
FAIL_IF_NULL(s);
DetectEngineCtxFree(de_ctx);
XBitsTestShutdown();
PASS;
}
static int DetectXBitsTestBadRules(void)
{
DetectEngineCtx *de_ctx = DetectEngineCtxInit();
FAIL_IF_NULL(de_ctx);
const char *sigs[] = {
"alert http any any -> any any (content:\"abc\"; xbits:set,bit1,noalert,track "
"ip_src;sid:1;)",
"alert http any any -> any any (content:\"abc\"; xbits:noalert,set,bit1,noalert,track "
"ip_src;sid:10;)",
"alert http any any -> any any (content:\"abc\"; xbits:isset,bit2,track "
"ip_dst,asdf;sid:2;)",
"alert http any any -> any any (content:\"abc\"; xbits:isnotset,track ip_pair;sid:3;)",
"alert http any any -> any any (content:\"abc\"; xbits:toggle,track ip_pair,bit4;sid:4;)",
"alert http any any -> any any (content:\"abc\"; xbits:unset,bit5,track ipsrc;sid:5;)",
"alert http any any -> any any (content:\"abc\"; xbits:bit6,set,track ip_src,expire "
"10;sid:6;)",
"alert http any any -> any any (content:\"abc\"; xbits:set,bit7,track "
"ip_pair,expire;sid:7;)",
"alert http any any -> any any (content:\"abc\"; xbits:set,bit7,trackk ip_pair,expire "
"3600, noalert;sid:8;)",
NULL,
};
const char **sig = sigs;
while (*sig) {
SCLogDebug("sig %s", *sig);
Signature *s = DetectEngineAppendSig(de_ctx, *sig);
FAIL_IF_NOT_NULL(s);
sig++;
}
DetectEngineCtxFree(de_ctx);
PASS;
}
static int DetectXBitsTestGoodRules(void)
{
DetectEngineCtx *de_ctx = DetectEngineCtxInit();
FAIL_IF_NULL(de_ctx);
const char *sigs[] = {
"alert http any any -> any any (content:\"abc\"; xbits:set,bit1,track ip_src;sid:1;)",
"alert http any any -> any any (content:\"abc\"; xbits:isset,bit2,track ip_dst;sid:2;)",
"alert http any any -> any any (content:\"abc\"; xbits:isnotset, bit3, track "
"ip_pair;sid:3;)",
"alert http any any -> any any (content:\"abc\"; xbits:toggle,bit4, track "
"ip_pair;sid:4;)",
"alert http any any -> any any (content:\"abc\"; xbits: unset ,bit5,track ip_src;sid:5;)",
"alert http any any -> any any (content:\"abc\"; xbits:set,bit6 ,track ip_src, expire "
"10 ;sid:6;)",
"alert http any any -> any any (content:\"abc\"; xbits:set, bit7, track ip_pair, expire "
"3600;sid:7;)",
"alert http any any -> any any (content:\"abc\"; xbits:set, bit7, track ip_pair, expire "
"3600; xbits:noalert; sid:8;)",
"alert http any any -> any any (content:\"abc\"; xbits:noalert; xbits:set, bit7, track "
"ip_pair, expire "
"3600;sid:9;)",
NULL,
};
const char **sig = sigs;
while (*sig) {
SCLogDebug("sig %s", *sig);
Signature *s = DetectEngineAppendSig(de_ctx, *sig);
FAIL_IF_NULL(s);
sig++;
}
DetectEngineCtxFree(de_ctx);
PASS;
}
/**
* \brief this function registers unit tests for XBits
*/
@ -632,5 +769,11 @@ static void XBitsRegisterTests(void)
UtRegisterTest("XBitsTestParse01", XBitsTestParse01);
UtRegisterTest("XBitsTestSig01", XBitsTestSig01);
UtRegisterTest("XBitsTestSig02", XBitsTestSig02);
UtRegisterTest("XBitsTestSig03", XBitsTestSig03);
UtRegisterTest("XBitsTestSig04", XBitsTestSig04);
UtRegisterTest("XBitsTestSig05", XBitsTestSig05);
UtRegisterTest("XBitsTestSig06", XBitsTestSig06);
UtRegisterTest("DetectXBitsTestBadRules", DetectXBitsTestBadRules);
UtRegisterTest("DetectXBitsTestGoodRules", DetectXBitsTestGoodRules);
}
#endif /* UNITTESTS */

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