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OCSP: parse signed certificate timestamps

Browse source 
With this change, we also parse signed certificate timestamps from OCSP
replies. This introduces a common base class between the OCSP and X509
analyzer, which now share a bit of common code. The event for signed
certificate timestamps is raised by both and thus renamed do:

x509_ocsp_ext_signed_certificate_timestamp
This commit is contained in:
Johanna Amann 2017-02-10 15:18:52 -08:00
parent b061a5db1a
commit c550521221
11 changed files with 404 additions and 391 deletions
Download patch file Download diff file Expand all files Collapse all files

157
src/file_analysis/analyzer/x509/Asn1Time.h
View file

@ -1,157 +0,0 @@
static double GetTimeFromAsn1(const ASN1_TIME* atime, const char* arg_fid, Reporter* reporter)
{
const char *fid = arg_fid ? arg_fid : "";
time_t lResult = 0;
char lBuffer[26];
char* pBuffer = lBuffer;
const char *pString = (const char *) atime->data;
unsigned int remaining = atime->length;
if ( atime->type == V_ASN1_UTCTIME )
{
if ( remaining < 11 || remaining > 17 )
{
reporter->Weird(fmt("Could not parse time in X509 certificate (fuid %s) -- UTCTime has wrong length", fid));
return 0;
}
if ( pString[remaining-1] != 'Z' )
{
// not valid according to RFC 2459 4.1.2.5.1
reporter->Weird(fmt("Could not parse UTC time in non-YY-format in X509 certificate (x509 %s)", fid));
return 0;
}
// year is first two digits in YY format. Buffer expects YYYY format.
if ( pString[0] < '5' ) // RFC 2459 4.1.2.5.1
{
*(pBuffer++) = '2';
*(pBuffer++) = '0';
}
else
{
*(pBuffer++) = '1';
*(pBuffer++) = '9';
}
memcpy(pBuffer, pString, 10);
pBuffer += 10;
pString += 10;
remaining -= 10;
}
else if ( atime->type == V_ASN1_GENERALIZEDTIME )
{
// generalized time. We apparently ignore the YYYYMMDDHH case
// for now and assume we always have minutes and seconds.
// This should be ok because it is specified as a requirement in RFC 2459 4.1.2.5.2
if ( remaining < 12 || remaining > 23 )
{
reporter->Weird(fmt("Could not parse time in X509 certificate (fuid %s) -- Generalized time has wrong length", fid));
return 0;
}
memcpy(pBuffer, pString, 12);
pBuffer += 12;
pString += 12;
remaining -= 12;
}
else
{
reporter->Weird(fmt("Invalid time type in X509 certificate (fuid %s)", fid));
return 0;
}
if ( (remaining == 0) || (*pString == 'Z') || (*pString == '-') || (*pString == '+') )
{
*(pBuffer++) = '0';
*(pBuffer++) = '0';
}
else if ( remaining >= 2 )
{
*(pBuffer++) = *(pString++);
*(pBuffer++) = *(pString++);
remaining -= 2;
// Skip any fractional seconds...
if ( (remaining > 0) && (*pString == '.') )
{
pString++;
remaining--;
while ( (remaining > 0) && (*pString >= '0') && (*pString <= '9') )
{
pString++;
remaining--;
}
}
}
else
{
reporter->Weird(fmt("Could not parse time in X509 certificate (fuid %s) -- additional char after time", fid));
return 0;
}
*(pBuffer++) = 'Z';
*(pBuffer++) = '\0';
time_t lSecondsFromUTC;
if ( remaining == 0 || *pString == 'Z' )
lSecondsFromUTC = 0;
else
{
if ( remaining < 5 )
{
reporter->Weird(fmt("Could not parse time in X509 certificate (fuid %s) -- not enough bytes remaining for offset", fid));
return 0;
}
if ((*pString != '+') && (*pString != '-'))
{
reporter->Weird(fmt("Could not parse time in X509 certificate (fuid %s) -- unknown offset type", fid));
return 0;
}
lSecondsFromUTC = ((pString[1] - '0') * 10 + (pString[2] - '0')) * 60;
lSecondsFromUTC += (pString[3] - '0') * 10 + (pString[4] - '0');
if (*pString == '-')
lSecondsFromUTC = -lSecondsFromUTC;
}
tm lTime;
lTime.tm_sec = ((lBuffer[12] - '0') * 10) + (lBuffer[13] - '0');
lTime.tm_min = ((lBuffer[10] - '0') * 10) + (lBuffer[11] - '0');
lTime.tm_hour = ((lBuffer[8] - '0') * 10) + (lBuffer[9] - '0');
lTime.tm_mday = ((lBuffer[6] - '0') * 10) + (lBuffer[7] - '0');
lTime.tm_mon = (((lBuffer[4] - '0') * 10) + (lBuffer[5] - '0')) - 1;
lTime.tm_year = (lBuffer[0] - '0') * 1000 + (lBuffer[1] - '0') * 100 + ((lBuffer[2] - '0') * 10) + (lBuffer[3] - '0');
if ( lTime.tm_year > 1900)
lTime.tm_year -= 1900;
lTime.tm_wday = 0;
lTime.tm_yday = 0;
lTime.tm_isdst = 0; // No DST adjustment requested
lResult = mktime(&lTime);
if ( lResult )
{
if ( lTime.tm_isdst != 0 )
lResult -= 3600; // mktime may adjust for DST (OS dependent)
lResult += lSecondsFromUTC;
}
else
lResult = 0;
return lResult;
}

2
src/file_analysis/analyzer/x509/CMakeLists.txt
View file

@ -5,7 +5,7 @@ include_directories(BEFORE ${CMAKE_CURRENT_SOURCE_DIR}
${CMAKE_CURRENT_BINARY_DIR}) ${CMAKE_CURRENT_BINARY_DIR})
bro_plugin_begin(Bro X509) bro_plugin_begin(Bro X509)
bro_plugin_cc(X509.cc OCSP.cc Plugin.cc) bro_plugin_cc(X509Common.cc X509.cc OCSP.cc Plugin.cc)
bro_plugin_bif(events.bif types.bif functions.bif ocsp_events.bif) bro_plugin_bif(events.bif types.bif functions.bif ocsp_events.bif)
bro_plugin_pac(x509-extension.pac x509-signed_certificate_timestamp.pac) bro_plugin_pac(x509-extension.pac x509-signed_certificate_timestamp.pac)
bro_plugin_end() bro_plugin_end()

61
src/file_analysis/analyzer/x509/OCSP.cc
View file

@ -17,7 +17,6 @@
#include <openssl/opensslconf.h> #include <openssl/opensslconf.h>
#include "file_analysis/analyzer/x509/X509.h" #include "file_analysis/analyzer/x509/X509.h"
#include "Asn1Time.h"
// helper function of sk_X509_value to avoid namespace problem // helper function of sk_X509_value to avoid namespace problem
// sk_X509_value(X,Y) = > SKM_sk_value(X509,X,Y) // sk_X509_value(X,Y) = > SKM_sk_value(X509,X,Y)
@ -87,7 +86,7 @@ file_analysis::Analyzer* OCSP::InstantiateReply(RecordVal* args, File* file)
} }
file_analysis::OCSP::OCSP(RecordVal* args, file_analysis::File* file, bool arg_request) file_analysis::OCSP::OCSP(RecordVal* args, file_analysis::File* file, bool arg_request)
: file_analysis::Analyzer(file_mgr->GetComponentTag("OCSP"), args, file), request(arg_request) : file_analysis::X509Common::X509Common(file_mgr->GetComponentTag("OCSP"), args, file), request(arg_request)
{ {
} }
@ -295,7 +294,7 @@ void file_analysis::OCSP::ParseResponse(OCSP_RESPVal *resp_val, const char* fid)
if ( ! ex ) if ( ! ex )
continue; continue;
ParseExtension(ex, false); ParseExtension(ex, ocsp_extension, false);
} }
} }
@ -334,63 +333,23 @@ void file_analysis::OCSP::ParseResponse(OCSP_RESPVal *resp_val, const char* fid)
if ( ! ex ) if ( ! ex )
continue; continue;
ParseExtension(ex, true); ParseExtension(ex, ocsp_extension, true);
} }
clean_up: clean_up:
if (basic_resp) if (basic_resp)
OCSP_BASICRESP_free(basic_resp); OCSP_BASICRESP_free(basic_resp);
BIO_free(bio); BIO_free(bio);
} }
// This is a near copy from X509 void file_analysis::OCSP::ParseExtensionsSpecific(X509_EXTENSION* ex, bool global, ASN1_OBJECT* ext_asn, const char* oid)
void file_analysis::OCSP::ParseExtension(X509_EXTENSION* ex, bool global)
{ {
char name[256]; #ifdef NID_ct_cert_scts
char oid[256]; if ( OBJ_obj2nid(ext_asn) == NID_ct_cert_scts || OBJ_obj2nid(ext_asn) == NID_ct_precert_scts )
#else
ASN1_OBJECT* ext_asn = X509_EXTENSION_get_object(ex); if ( strcmp(oid, "1.3.6.1.4.1.11129.2.4.2") == 0 || strcmp(oid, "1.3.6.1.4.1.11129.2.4.4") == 0 )
const char* short_name = OBJ_nid2sn(OBJ_obj2nid(ext_asn)); #endif
ParseSignedCertificateTimestamps(ex);
OBJ_obj2txt(name, 255, ext_asn, 0);
OBJ_obj2txt(oid, 255, ext_asn, 1);
int critical = 0;
if ( X509_EXTENSION_get_critical(ex) != 0 )
critical = 1;
BIO *bio = BIO_new(BIO_s_mem());
if( ! X509V3_EXT_print(bio, ex, 0, 0))
M_ASN1_OCTET_STRING_print(bio,ex->value);
StringVal* ext_val = X509::GetExtensionFromBIO(bio);
if ( ! ext_val )
ext_val = new StringVal(0, "");
RecordVal* pX509Ext = new RecordVal(BifType::Record::X509::Extension);
pX509Ext->Assign(0, new StringVal(name));
if ( short_name and strlen(short_name) > 0 )
pX509Ext->Assign(1, new StringVal(short_name));
pX509Ext->Assign(2, new StringVal(oid));
pX509Ext->Assign(3, new Val(critical, TYPE_BOOL));
pX509Ext->Assign(4, ext_val);
// send off generic extension event
//
// and then look if we have a specialized event for the extension we just
// parsed. And if we have it, we send the specialized event on top of the
// generic event that we just had. I know, that is... kind of not nice,
// but I am not sure if there is a better way to do it...
val_list* vl = new val_list();
vl->append(GetFile()->GetVal()->Ref());
vl->append(pX509Ext);
vl->append(new Val(global ? 1 : 0, TYPE_BOOL));
mgr.QueueEvent(ocsp_extension, vl);
} }
OCSP_RESPVal::OCSP_RESPVal(OCSP_RESPONSE* arg_ocsp_resp) : OpaqueVal(ocsp_resp_opaque_type) OCSP_RESPVal::OCSP_RESPVal(OCSP_RESPONSE* arg_ocsp_resp) : OpaqueVal(ocsp_resp_opaque_type)

13
src/file_analysis/analyzer/x509/OCSP.h
View file

@ -8,20 +8,19 @@
#include "Val.h" #include "Val.h"
#include "../File.h" #include "../File.h"
#include "Analyzer.h" #include "Analyzer.h"
#include "X509Common.h"
#include <openssl/ocsp.h> #include <openssl/ocsp.h>
#include <openssl/x509.h>
#include <openssl/asn1.h>
namespace file_analysis { namespace file_analysis {
class OCSP_RESPVal; class OCSP_RESPVal;
class OCSP : public file_analysis::Analyzer { class OCSP : public file_analysis::X509Common {
public: public:
virtual bool DeliverStream(const u_char* data, uint64 len); bool DeliverStream(const u_char* data, uint64 len) override;
virtual bool Undelivered(uint64 offset, uint64 len); bool Undelivered(uint64 offset, uint64 len) override;
virtual bool EndOfFile(); bool EndOfFile() override;
static file_analysis::Analyzer* InstantiateRequest(RecordVal* args, File* file); static file_analysis::Analyzer* InstantiateRequest(RecordVal* args, File* file);
static file_analysis::Analyzer* InstantiateReply(RecordVal* args, File* file); static file_analysis::Analyzer* InstantiateReply(RecordVal* args, File* file);
@ -32,7 +31,7 @@ protected:
private: private:
void ParseResponse(OCSP_RESPVal *, const char* fid = 0); void ParseResponse(OCSP_RESPVal *, const char* fid = 0);
void ParseRequest(OCSP_REQUEST *, const char* fid = 0); void ParseRequest(OCSP_REQUEST *, const char* fid = 0);
void ParseExtension(X509_EXTENSION*, bool global); void ParseExtensionsSpecific(X509_EXTENSION* ex, bool, ASN1_OBJECT*, const char*) override;
std::string ocsp_data; std::string ocsp_data;
bool request = false; // true if ocsp request, false if reply bool request = false; // true if ocsp request, false if reply

170
src/file_analysis/analyzer/x509/X509.cc
View file

@ -4,7 +4,6 @@
#include "X509.h" #include "X509.h"
#include "Event.h" #include "Event.h"
#include "x509-extension_pac.h"
#include "events.bif.h" #include "events.bif.h"
#include "types.bif.h" #include "types.bif.h"
@ -17,14 +16,12 @@
#include <openssl/opensslconf.h> #include <openssl/opensslconf.h>
#include <openssl/err.h> #include <openssl/err.h>
#include "Asn1Time.h"
using namespace file_analysis; using namespace file_analysis;
IMPLEMENT_SERIAL(X509Val, SER_X509_VAL); IMPLEMENT_SERIAL(X509Val, SER_X509_VAL);
file_analysis::X509::X509(RecordVal* args, file_analysis::File* file) file_analysis::X509::X509(RecordVal* args, file_analysis::File* file)
: file_analysis::Analyzer(file_mgr->GetComponentTag("X509"), args, file) : file_analysis::X509Common::X509Common(file_mgr->GetComponentTag("X509"), args, file)
{ {
cert_data.clear(); cert_data.clear();
} }
@ -75,7 +72,7 @@ bool file_analysis::X509::EndOfFile()
if ( ! ex ) if ( ! ex )
continue; continue;
ParseExtension(ex); ParseExtension(ex, x509_extension, false);
} }
// X509_free(ssl_cert); We do _not_ free the certificate here. It is refcounted // X509_free(ssl_cert); We do _not_ free the certificate here. It is refcounted
@ -208,152 +205,6 @@ RecordVal* file_analysis::X509::ParseCertificate(X509Val* cert_val, const char*
return pX509Cert; return pX509Cert;
} }
StringVal* file_analysis::X509::GetExtensionFromBIO(BIO* bio)
{
BIO_flush(bio);
ERR_clear_error();
int length = BIO_pending(bio);
if ( ERR_peek_error() != 0 )
{
char tmp[120];
ERR_error_string_n(ERR_get_error(), tmp, sizeof(tmp));
reporter->Weird(fmt("X509::GetExtensionFromBIO: %s", tmp));
BIO_free_all(bio);
return 0;
}
if ( length == 0 )
{
BIO_free_all(bio);
return new StringVal("");
}
char* buffer = (char*) malloc(length);
if ( ! buffer )
{
// Just emit an error here and try to continue instead of aborting
// because it's unclear the length value is very reliable.
reporter->Error("X509::GetExtensionFromBIO malloc(%d) failed", length);
BIO_free_all(bio);
return 0;
}
BIO_read(bio, (void*) buffer, length);
StringVal* ext_val = new StringVal(length, buffer);
free(buffer);
BIO_free_all(bio);
return ext_val;
}
// this is nearly replicated in the OCSP analyzer
void file_analysis::X509::ParseExtension(X509_EXTENSION* ex)
{
char name[256];
char oid[256];
ASN1_OBJECT* ext_asn = X509_EXTENSION_get_object(ex);
const char* short_name = OBJ_nid2sn(OBJ_obj2nid(ext_asn));
OBJ_obj2txt(name, 255, ext_asn, 0);
OBJ_obj2txt(oid, 255, ext_asn, 1);
int critical = 0;
if ( X509_EXTENSION_get_critical(ex) != 0 )
critical = 1;
BIO *bio = BIO_new(BIO_s_mem());
if( ! X509V3_EXT_print(bio, ex, 0, 0))
M_ASN1_OCTET_STRING_print(bio,ex->value);
StringVal* ext_val = GetExtensionFromBIO(bio);
if ( ! ext_val )
ext_val = new StringVal(0, "");
RecordVal* pX509Ext = new RecordVal(BifType::Record::X509::Extension);
pX509Ext->Assign(0, new StringVal(name));
if ( short_name and strlen(short_name) > 0 )
pX509Ext->Assign(1, new StringVal(short_name));
pX509Ext->Assign(2, new StringVal(oid));
pX509Ext->Assign(3, new Val(critical, TYPE_BOOL));
pX509Ext->Assign(4, ext_val);
// send off generic extension event
//
// and then look if we have a specialized event for the extension we just
// parsed. And if we have it, we send the specialized event on top of the
// generic event that we just had. I know, that is... kind of not nice,
// but I am not sure if there is a better way to do it...
val_list* vl = new val_list();
vl->append(GetFile()->GetVal()->Ref());
vl->append(pX509Ext);
mgr.QueueEvent(x509_extension, vl);
// look if we have a specialized handler for this event...
if ( OBJ_obj2nid(ext_asn) == NID_basic_constraints )
ParseBasicConstraints(ex);
else if ( OBJ_obj2nid(ext_asn) == NID_subject_alt_name )
ParseSAN(ex);
#ifdef NID_ct_cert_scts
else if ( OBJ_obj2nid(ext_asn) == NID_ct_cert_scts || OBJ_obj2nid(ext_asn) == NID_ct_precert_scts )
#else
else if ( strcmp(oid, "1.3.6.1.4.1.11129.2.4.2") == 0 || strcmp(oid, "1.3.6.1.4.1.11129.2.4.4") == 0 )
#endif
ParseSignedCertificateTimestamps(ex);
}
void file_analysis::X509::ParseSignedCertificateTimestamps(X509_EXTENSION* ext)
{
// Ok, signed certificate timestamps are a bit of an odd case out; we don't
// want to use the (basically nonexistant) OpenSSL functionality to parse them.
// Instead we have our own, self-written binpac parser to parse just them,
// which we will initialize here and tear down immediately again.
ASN1_OCTET_STRING* ext_val = X509_EXTENSION_get_data(ext);
// the octet string of the extension contains the octet string which in turn
// contains the SCT. Obviously.
unsigned char* ext_val_copy = (unsigned char*) OPENSSL_malloc(ext_val->length);
unsigned char* ext_val_second_pointer = ext_val_copy;
memcpy(ext_val_copy, ext_val->data, ext_val->length);
ASN1_OCTET_STRING* inner = d2i_ASN1_OCTET_STRING(NULL, (const unsigned char**) &ext_val_copy, ext_val->length);
if ( !inner )
{
reporter->Error("X509::ParseSignedCertificateTimestamps could not parse inner octet string");
return;
}
binpac::X509Extension::MockConnection* conn = new binpac::X509Extension::MockConnection(this);
binpac::X509Extension::SignedCertTimestampExt* interp = new binpac::X509Extension::SignedCertTimestampExt(conn);
try
{
interp->NewData(inner->data, inner->data + inner->length);
}
catch( const binpac::Exception& e )
{
// throw a warning or sth
reporter->Error("X509::ParseSignedCertificateTimestamps could not parse SCT");
}
OPENSSL_free(ext_val_second_pointer);
interp->FlowEOF();
delete interp;
delete conn;
}
void file_analysis::X509::ParseBasicConstraints(X509_EXTENSION* ex) void file_analysis::X509::ParseBasicConstraints(X509_EXTENSION* ex)
{ {
assert(OBJ_obj2nid(X509_EXTENSION_get_object(ex)) == NID_basic_constraints); assert(OBJ_obj2nid(X509_EXTENSION_get_object(ex)) == NID_basic_constraints);
@ -380,6 +231,23 @@ void file_analysis::X509::ParseBasicConstraints(X509_EXTENSION* ex)
reporter->Weird(fmt("Certificate with invalid BasicConstraint. fuid %s", GetFile()->GetID().c_str())); reporter->Weird(fmt("Certificate with invalid BasicConstraint. fuid %s", GetFile()->GetID().c_str()));
} }
void file_analysis::X509::ParseExtensionsSpecific(X509_EXTENSION* ex, bool global, ASN1_OBJECT* ext_asn, const char* oid)
{
// look if we have a specialized handler for this event...
if ( OBJ_obj2nid(ext_asn) == NID_basic_constraints )
ParseBasicConstraints(ex);
else if ( OBJ_obj2nid(ext_asn) == NID_subject_alt_name )
ParseSAN(ex);
#ifdef NID_ct_cert_scts
else if ( OBJ_obj2nid(ext_asn) == NID_ct_cert_scts || OBJ_obj2nid(ext_asn) == NID_ct_precert_scts )
#else
else if ( strcmp(oid, "1.3.6.1.4.1.11129.2.4.2") == 0 || strcmp(oid, "1.3.6.1.4.1.11129.2.4.4") == 0 )
#endif
ParseSignedCertificateTimestamps(ex);
}
void file_analysis::X509::ParseSAN(X509_EXTENSION* ext) void file_analysis::X509::ParseSAN(X509_EXTENSION* ext)
{ {
assert(OBJ_obj2nid(X509_EXTENSION_get_object(ext)) == NID_subject_alt_name); assert(OBJ_obj2nid(X509_EXTENSION_get_object(ext)) == NID_subject_alt_name);

27
src/file_analysis/analyzer/x509/X509.h
View file

@ -6,21 +6,18 @@
#include <string> #include <string>
#include "Val.h" #include "Val.h"
#include "../File.h" #include "X509Common.h"
#include "Analyzer.h"
#include <openssl/x509.h>
#include <openssl/asn1.h>
namespace file_analysis { namespace file_analysis {
class X509Val; class X509Val;
class X509 : public file_analysis::Analyzer { class X509 : public file_analysis::X509Common {
public: public:
virtual bool DeliverStream(const u_char* data, uint64 len); bool DeliverStream(const u_char* data, uint64 len) override;
virtual bool Undelivered(uint64 offset, uint64 len); bool Undelivered(uint64 offset, uint64 len) override;
virtual bool EndOfFile(); bool EndOfFile() override;
/** /**
* Converts an X509 certificate into a \c X509::Certificate record * Converts an X509 certificate into a \c X509::Certificate record
@ -40,25 +37,13 @@ public:
static file_analysis::Analyzer* Instantiate(RecordVal* args, File* file) static file_analysis::Analyzer* Instantiate(RecordVal* args, File* file)
{ return new X509(args, file); } { return new X509(args, file); }
/**
* Retrieve an X509 extension value from an OpenSSL BIO to which it was
* written.
*
* @param bio the OpenSSL BIO to read. It will be freed by the function,
* including when an error occurs.
*
* @return The X509 extension value.
*/
static StringVal* GetExtensionFromBIO(BIO* bio);
protected: protected:
X509(RecordVal* args, File* file); X509(RecordVal* args, File* file);
private: private:
void ParseExtension(X509_EXTENSION* ex);
void ParseBasicConstraints(X509_EXTENSION* ex); void ParseBasicConstraints(X509_EXTENSION* ex);
void ParseSAN(X509_EXTENSION* ex); void ParseSAN(X509_EXTENSION* ex);
void ParseSignedCertificateTimestamps(X509_EXTENSION* ext); void ParseExtensionsSpecific(X509_EXTENSION* ex, bool, ASN1_OBJECT*, const char*) override;
std::string cert_data; std::string cert_data;

315
src/file_analysis/analyzer/x509/X509Common.cc Normal file
View file

@ -0,0 +1,315 @@
// See the file "COPYING" in the main distribution directory for copyright.
#include "X509Common.h"
#include "x509-extension_pac.h"
#include "events.bif.h"
#include "ocsp_events.bif.h"
#include "types.bif.h"
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include <openssl/asn1.h>
#include <openssl/opensslconf.h>
#include <openssl/err.h>
using namespace file_analysis;
X509Common::X509Common(file_analysis::Tag arg_tag, RecordVal* arg_args, File* arg_file)
: file_analysis::Analyzer(arg_tag, arg_args, arg_file)
{
}
double X509Common::GetTimeFromAsn1(const ASN1_TIME* atime, const char* arg_fid, Reporter* reporter)
{
const char *fid = arg_fid ? arg_fid : "";
time_t lResult = 0;
char lBuffer[26];
char* pBuffer = lBuffer;
const char *pString = (const char *) atime->data;
unsigned int remaining = atime->length;
if ( atime->type == V_ASN1_UTCTIME )
{
if ( remaining < 11 || remaining > 17 )
{
reporter->Weird(fmt("Could not parse time in X509 certificate (fuid %s) -- UTCTime has wrong length", fid));
return 0;
}
if ( pString[remaining-1] != 'Z' )
{
// not valid according to RFC 2459 4.1.2.5.1
reporter->Weird(fmt("Could not parse UTC time in non-YY-format in X509 certificate (x509 %s)", fid));
return 0;
}
// year is first two digits in YY format. Buffer expects YYYY format.
if ( pString[0] < '5' ) // RFC 2459 4.1.2.5.1
{
*(pBuffer++) = '2';
*(pBuffer++) = '0';
}
else
{
*(pBuffer++) = '1';
*(pBuffer++) = '9';
}
memcpy(pBuffer, pString, 10);
pBuffer += 10;
pString += 10;
remaining -= 10;
}
else if ( atime->type == V_ASN1_GENERALIZEDTIME )
{
// generalized time. We apparently ignore the YYYYMMDDHH case
// for now and assume we always have minutes and seconds.
// This should be ok because it is specified as a requirement in RFC 2459 4.1.2.5.2
if ( remaining < 12 || remaining > 23 )
{
reporter->Weird(fmt("Could not parse time in X509 certificate (fuid %s) -- Generalized time has wrong length", fid));
return 0;
}
memcpy(pBuffer, pString, 12);
pBuffer += 12;
pString += 12;
remaining -= 12;
}
else
{
reporter->Weird(fmt("Invalid time type in X509 certificate (fuid %s)", fid));
return 0;
}
if ( (remaining == 0) || (*pString == 'Z') || (*pString == '-') || (*pString == '+') )
{
*(pBuffer++) = '0';
*(pBuffer++) = '0';
}
else if ( remaining >= 2 )
{
*(pBuffer++) = *(pString++);
*(pBuffer++) = *(pString++);
remaining -= 2;
// Skip any fractional seconds...
if ( (remaining > 0) && (*pString == '.') )
{
pString++;
remaining--;
while ( (remaining > 0) && (*pString >= '0') && (*pString <= '9') )
{
pString++;
remaining--;
}
}
}
else
{
reporter->Weird(fmt("Could not parse time in X509 certificate (fuid %s) -- additional char after time", fid));
return 0;
}
*(pBuffer++) = 'Z';
*(pBuffer++) = '\0';
time_t lSecondsFromUTC;
if ( remaining == 0 || *pString == 'Z' )
lSecondsFromUTC = 0;
else
{
if ( remaining < 5 )
{
reporter->Weird(fmt("Could not parse time in X509 certificate (fuid %s) -- not enough bytes remaining for offset", fid));
return 0;
}
if ((*pString != '+') && (*pString != '-'))
{
reporter->Weird(fmt("Could not parse time in X509 certificate (fuid %s) -- unknown offset type", fid));
return 0;
}
lSecondsFromUTC = ((pString[1] - '0') * 10 + (pString[2] - '0')) * 60;
lSecondsFromUTC += (pString[3] - '0') * 10 + (pString[4] - '0');
if (*pString == '-')
lSecondsFromUTC = -lSecondsFromUTC;
}
tm lTime;
lTime.tm_sec = ((lBuffer[12] - '0') * 10) + (lBuffer[13] - '0');
lTime.tm_min = ((lBuffer[10] - '0') * 10) + (lBuffer[11] - '0');
lTime.tm_hour = ((lBuffer[8] - '0') * 10) + (lBuffer[9] - '0');
lTime.tm_mday = ((lBuffer[6] - '0') * 10) + (lBuffer[7] - '0');
lTime.tm_mon = (((lBuffer[4] - '0') * 10) + (lBuffer[5] - '0')) - 1;
lTime.tm_year = (lBuffer[0] - '0') * 1000 + (lBuffer[1] - '0') * 100 + ((lBuffer[2] - '0') * 10) + (lBuffer[3] - '0');
if ( lTime.tm_year > 1900)
lTime.tm_year -= 1900;
lTime.tm_wday = 0;
lTime.tm_yday = 0;
lTime.tm_isdst = 0; // No DST adjustment requested
lResult = mktime(&lTime);
if ( lResult )
{
if ( lTime.tm_isdst != 0 )
lResult -= 3600; // mktime may adjust for DST (OS dependent)
lResult += lSecondsFromUTC;
}
else
lResult = 0;
return lResult;
}
void file_analysis::X509Common::ParseSignedCertificateTimestamps(X509_EXTENSION* ext)
{
// Ok, signed certificate timestamps are a bit of an odd case out; we don't
// want to use the (basically nonexistant) OpenSSL functionality to parse them.
// Instead we have our own, self-written binpac parser to parse just them,
// which we will initialize here and tear down immediately again.
ASN1_OCTET_STRING* ext_val = X509_EXTENSION_get_data(ext);
// the octet string of the extension contains the octet string which in turn
// contains the SCT. Obviously.
unsigned char* ext_val_copy = (unsigned char*) OPENSSL_malloc(ext_val->length);
unsigned char* ext_val_second_pointer = ext_val_copy;
memcpy(ext_val_copy, ext_val->data, ext_val->length);
ASN1_OCTET_STRING* inner = d2i_ASN1_OCTET_STRING(NULL, (const unsigned char**) &ext_val_copy, ext_val->length);
if ( !inner )
{
reporter->Error("X509::ParseSignedCertificateTimestamps could not parse inner octet string");
return;
}
binpac::X509Extension::MockConnection* conn = new binpac::X509Extension::MockConnection(this);
binpac::X509Extension::SignedCertTimestampExt* interp = new binpac::X509Extension::SignedCertTimestampExt(conn);
try
{
interp->NewData(inner->data, inner->data + inner->length);
}
catch( const binpac::Exception& e )
{
// throw a warning or sth
reporter->Error("X509::ParseSignedCertificateTimestamps could not parse SCT");
}
OPENSSL_free(ext_val_second_pointer);
interp->FlowEOF();
delete interp;
delete conn;
}
void file_analysis::X509Common::ParseExtension(X509_EXTENSION* ex, EventHandlerPtr h, bool global)
{
char name[256];
char oid[256];
ASN1_OBJECT* ext_asn = X509_EXTENSION_get_object(ex);
const char* short_name = OBJ_nid2sn(OBJ_obj2nid(ext_asn));
OBJ_obj2txt(name, 255, ext_asn, 0);
OBJ_obj2txt(oid, 255, ext_asn, 1);
int critical = 0;
if ( X509_EXTENSION_get_critical(ex) != 0 )
critical = 1;
BIO *bio = BIO_new(BIO_s_mem());
if( ! X509V3_EXT_print(bio, ex, 0, 0))
M_ASN1_OCTET_STRING_print(bio,ex->value);
StringVal* ext_val = GetExtensionFromBIO(bio);
if ( ! ext_val )
ext_val = new StringVal(0, "");
RecordVal* pX509Ext = new RecordVal(BifType::Record::X509::Extension);
pX509Ext->Assign(0, new StringVal(name));
if ( short_name and strlen(short_name) > 0 )
pX509Ext->Assign(1, new StringVal(short_name));
pX509Ext->Assign(2, new StringVal(oid));
pX509Ext->Assign(3, new Val(critical, TYPE_BOOL));
pX509Ext->Assign(4, ext_val);
// send off generic extension event
//
// and then look if we have a specialized event for the extension we just
// parsed. And if we have it, we send the specialized event on top of the
// generic event that we just had. I know, that is... kind of not nice,
// but I am not sure if there is a better way to do it...
val_list* vl = new val_list();
vl->append(GetFile()->GetVal()->Ref());
vl->append(pX509Ext);
if ( h == ocsp_extension )
vl->append(new Val(global ? 1 : 0, TYPE_BOOL));
mgr.QueueEvent(h, vl);
// let individual analyzers parse more.
ParseExtensionsSpecific(ex, global, ext_asn, oid);
}
StringVal* file_analysis::X509Common::GetExtensionFromBIO(BIO* bio)
{
BIO_flush(bio);
ERR_clear_error();
int length = BIO_pending(bio);
if ( ERR_peek_error() != 0 )
{
char tmp[120];
ERR_error_string_n(ERR_get_error(), tmp, sizeof(tmp));
reporter->Weird(fmt("X509::GetExtensionFromBIO: %s", tmp));
BIO_free_all(bio);
return 0;
}
if ( length == 0 )
{
BIO_free_all(bio);
return new StringVal("");
}
char* buffer = (char*) malloc(length);
if ( ! buffer )
{
// Just emit an error here and try to continue instead of aborting
// because it's unclear the length value is very reliable.
reporter->Error("X509::GetExtensionFromBIO malloc(%d) failed", length);
BIO_free_all(bio);
return 0;
}
BIO_read(bio, (void*) buffer, length);
StringVal* ext_val = new StringVal(length, buffer);
free(buffer);
BIO_free_all(bio);
return ext_val;
}

44
src/file_analysis/analyzer/x509/X509Common.h Normal file
View file

@ -0,0 +1,44 @@
// See the file "COPYING" in the main distribution directory for copyright.
// Common base class for the X509 and OCSP analyzer, which share a fair amount of
// code
#ifndef FILE_ANALYSIS_X509_COMMON
#define FILE_ANALYSIS_X509_COMMON
#include "../File.h"
#include "Analyzer.h"
#include <openssl/x509.h>
#include <openssl/asn1.h>
namespace file_analysis {
class X509Common : public file_analysis::Analyzer {
public:
virtual ~X509Common() {};
/**
* Retrieve an X509 extension value from an OpenSSL BIO to which it was
* written.
*
* @param bio the OpenSSL BIO to read. It will be freed by the function,
* including when an error occurs.
*
* @return The X509 extension value.
*/
static StringVal* GetExtensionFromBIO(BIO* bio);
static double GetTimeFromAsn1(const ASN1_TIME* atime, const char* arg_fid, Reporter* reporter);
protected:
X509Common(file_analysis::Tag arg_tag, RecordVal* arg_args, File* arg_file);
void ParseExtension(X509_EXTENSION* ex, EventHandlerPtr h, bool global);
void ParseSignedCertificateTimestamps(X509_EXTENSION* ext);
virtual void ParseExtensionsSpecific(X509_EXTENSION* ex, bool, ASN1_OBJECT*, const char*) = 0;
};
}
#endif /* FILE_ANALYSIS_X509_COMMON */

2
src/file_analysis/analyzer/x509/events.bif
View file

@ -73,4 +73,4 @@ event x509_ext_subject_alternative_name%(f: fa_file, ext: X509::SubjectAlternati
## digitally_signed struct ## digitally_signed struct
## ##
## signature: signature part of the digitally_signed struct ## signature: signature part of the digitally_signed struct
event x509_ext_signed_certificate_timestamp%(f: fa_file, version: count, logid: string, timestamp: time, hash_algorithm: count, signature_algorithm: count, signature: string%); event x509_ocsp_ext_signed_certificate_timestamp%(f: fa_file, version: count, logid: string, timestamp: time, hash_algorithm: count, signature_algorithm: count, signature: string%);

2
src/file_analysis/analyzer/x509/x509-extension.pac
View file

@ -35,7 +35,7 @@ refine connection MockConnection += {
function proc_signedcertificatetimestamp(rec: HandshakeRecord, version: uint8, logid: const_bytestring, timestamp: uint64, digitally_signed_algorithms: SignatureAndHashAlgorithm, digitally_signed_signature: const_bytestring) : bool function proc_signedcertificatetimestamp(rec: HandshakeRecord, version: uint8, logid: const_bytestring, timestamp: uint64, digitally_signed_algorithms: SignatureAndHashAlgorithm, digitally_signed_signature: const_bytestring) : bool
%{ %{
BifEvent::generate_x509_ext_signed_certificate_timestamp((analyzer::Analyzer *) bro_analyzer(), BifEvent::generate_x509_ocsp_ext_signed_certificate_timestamp((analyzer::Analyzer *) bro_analyzer(),
bro_analyzer()->GetFile()->GetVal()->Ref(), bro_analyzer()->GetFile()->GetVal()->Ref(),
version, version,
new StringVal(logid.length(), reinterpret_cast<const char*>(logid.begin())), new StringVal(logid.length(), reinterpret_cast<const char*>(logid.begin())),

2
testing/btest/scripts/base/files/x509/signed_certificate_timestamp.test
View file

@ -1,7 +1,7 @@
# @TEST-EXEC: bro -r $TRACES/tls/certificate-with-sct.pcap %INPUT # @TEST-EXEC: bro -r $TRACES/tls/certificate-with-sct.pcap %INPUT
# @TEST-EXEC: btest-diff .stdout # @TEST-EXEC: btest-diff .stdout
event x509_ext_signed_certificate_timestamp(f: fa_file, version: count, logid: string, timestamp: time, hash_algorithm: count, signature_algorithm: count, signature: string) event x509_ocsp_ext_signed_certificate_timestamp(f: fa_file, version: count, logid: string, timestamp: time, hash_algorithm: count, signature_algorithm: count, signature: string)
{ {
print version, timestamp, hash_algorithm, signature_algorithm; print version, timestamp, hash_algorithm, signature_algorithm;
} }