From e974dbea0ea0d608634f4d7086ebc2a7336212cb Mon Sep 17 00:00:00 2001 From: Philippe Antoine Date: Thu, 9 Nov 2023 09:57:58 +0100 Subject: [PATCH] detect: header_lowercase transform Ticket: 6290 (cherry picked from commit 32cce122e1d8bb568cd5ff1b0db51c488cfb9f58) --- doc/userguide/rules/transforms.rst | 16 +++++ src/Makefile.am | 2 + src/detect-engine-register.c | 2 + src/detect-engine-register.h | 1 + src/detect-transform-header-lowercase.c | 88 +++++++++++++++++++++++++ src/detect-transform-header-lowercase.h | 30 +++++++++ 6 files changed, 139 insertions(+) create mode 100644 src/detect-transform-header-lowercase.c create mode 100644 src/detect-transform-header-lowercase.h diff --git a/doc/userguide/rules/transforms.rst b/doc/userguide/rules/transforms.rst index 91ab2ef5fc..fecd1c537b 100644 --- a/doc/userguide/rules/transforms.rst +++ b/doc/userguide/rules/transforms.rst @@ -134,3 +134,19 @@ Example:: alert http any any -> any any (msg:"HTTP with xor"; http.uri; \ xor:"0d0ac8ff"; content:"password="; sid:1;) + +header_lowercase +---------------- + +This transform is meant for HTTP/1 HTTP/2 header names normalization. +It lowercases the header names, while keeping untouched the header values. + +The implementation uses a state machine : +- it lowercases until it finds ``:``` +- it does not change until it finds a new line and switch back to first state + +This example alerts for both HTTP/1 and HTTP/2 with a authorization header +Example:: + + alert http any any -> any any (msg:"HTTP authorization"; http.header_names; \ + header_lowercase; content:"authorization:"; sid:1;) diff --git a/src/Makefile.am b/src/Makefile.am index 48a5ce850c..8253f40301 100755 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -339,6 +339,7 @@ noinst_HEADERS = \ detect-tos.h \ detect-transform-compress-whitespace.h \ detect-transform-dotprefix.h \ + detect-transform-header-lowercase.h \ detect-transform-md5.h \ detect-transform-pcrexform.h \ detect-transform-sha1.h \ @@ -948,6 +949,7 @@ libsuricata_c_a_SOURCES = \ detect-tos.c \ detect-transform-compress-whitespace.c \ detect-transform-dotprefix.c \ + detect-transform-header-lowercase.c \ detect-transform-md5.c \ detect-transform-pcrexform.c \ detect-transform-sha1.c \ diff --git a/src/detect-engine-register.c b/src/detect-engine-register.c index df6e4a738f..6ab7f94c10 100644 --- a/src/detect-engine-register.c +++ b/src/detect-engine-register.c @@ -244,6 +244,7 @@ #include "detect-transform-pcrexform.h" #include "detect-transform-urldecode.h" #include "detect-transform-xor.h" +#include "detect-transform-header-lowercase.h" #include "util-rule-vars.h" @@ -696,6 +697,7 @@ void SigTableSetup(void) DetectTransformPcrexformRegister(); DetectTransformUrlDecodeRegister(); DetectTransformXorRegister(); + DetectTransformHeaderLowercaseRegister(); DetectFileHandlerRegister(); diff --git a/src/detect-engine-register.h b/src/detect-engine-register.h index 7d6c457ef9..1c606125ab 100644 --- a/src/detect-engine-register.h +++ b/src/detect-engine-register.h @@ -321,6 +321,7 @@ enum DetectKeywordId { DETECT_TRANSFORM_PCREXFORM, DETECT_TRANSFORM_URL_DECODE, DETECT_TRANSFORM_XOR, + DETECT_TRANSFORM_HEADER_LOWERCASE, DETECT_AL_IKE_EXCH_TYPE, DETECT_AL_IKE_SPI_INITIATOR, diff --git a/src/detect-transform-header-lowercase.c b/src/detect-transform-header-lowercase.c new file mode 100644 index 0000000000..7c776201b3 --- /dev/null +++ b/src/detect-transform-header-lowercase.c @@ -0,0 +1,88 @@ +/* Copyright (C) 2023 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 + * + * \author Philippe Antoine + * + * Implements the header_lowercase transform keyword with option support + */ + +#include "suricata-common.h" +#include "detect.h" +#include "detect-engine.h" +#include "detect-parse.h" +#include "detect-transform-header-lowercase.h" + +/** + * \internal + * \brief Apply the header_lowercase keyword to the last pattern match + * \param det_ctx detection engine ctx + * \param s signature + * \param optstr options string + * \retval 0 ok + * \retval -1 failure + */ +static int DetectTransformHeaderLowercaseSetup( + DetectEngineCtx *de_ctx, Signature *s, const char *optstr) +{ + SCEnter(); + int r = DetectSignatureAddTransform(s, DETECT_TRANSFORM_HEADER_LOWERCASE, NULL); + SCReturnInt(r); +} + +static void DetectTransformHeaderLowercase(InspectionBuffer *buffer, void *options) +{ + const uint8_t *input = buffer->inspect; + const uint32_t input_len = buffer->inspect_len; + if (input_len == 0) { + return; + } + uint8_t output[input_len]; + + // state 0 is header name, 1 is header value + int state = 0; + for (uint32_t i = 0; i < input_len; i++) { + if (state == 0) { + if (input[i] == ':') { + output[i] = input[i]; + state = 1; + } else { + output[i] = u8_tolower(input[i]); + } + } else { + output[i] = input[i]; + if (input[i] == '\n') { + state = 0; + } + } + } + InspectionBufferCopy(buffer, output, input_len); +} + +void DetectTransformHeaderLowercaseRegister(void) +{ + sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].name = "header_lowercase"; + sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].desc = + "modify buffer via lowercaseing header names"; + sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].url = + "/rules/transforms.html#header_lowercase"; + sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].Transform = DetectTransformHeaderLowercase; + sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].Setup = DetectTransformHeaderLowercaseSetup; + sigmatch_table[DETECT_TRANSFORM_HEADER_LOWERCASE].flags |= SIGMATCH_NOOPT; +} diff --git a/src/detect-transform-header-lowercase.h b/src/detect-transform-header-lowercase.h new file mode 100644 index 0000000000..aca7f874a4 --- /dev/null +++ b/src/detect-transform-header-lowercase.h @@ -0,0 +1,30 @@ +/* Copyright (C) 2023 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 + * + * \author Philippe Antoine + */ + +#ifndef __DETECT_TRANSFORM_HEADER_LOWERCASE_H__ +#define __DETECT_TRANSFORM_HEADER_LOWERCASE_H__ + +/* prototypes */ +void DetectTransformHeaderLowercaseRegister(void); + +#endif /* __DETECT_TRANSFORM_HEADER_LOWERCASE_H__ */ -- 2.47.2