diff --git a/lib/controller/checks.py b/lib/controller/checks.py
index e9c387b41..4aa005d10 100644
--- a/lib/controller/checks.py
+++ b/lib/controller/checks.py
@@ -22,6 +22,7 @@ from lib.core.common import extractTextTagContent
 from lib.core.common import findDynamicContent
 from lib.core.common import Format
 from lib.core.common import getLastRequestHTTPError
+from lib.core.common import getPublicTypeMembers
 from lib.core.common import getSortedInjectionTests
 from lib.core.common import getUnicode
 from lib.core.common import intersect
@@ -42,6 +43,8 @@ from lib.core.data import kb
 from lib.core.data import logger
 from lib.core.datatype import AttribDict
 from lib.core.datatype import InjectionDict
+from lib.core.dicts import FROM_DUMMY_TABLE
+from lib.core.enums import DBMS
 from lib.core.enums import HEURISTIC_TEST
 from lib.core.enums import HTTPHEADER
 from lib.core.enums import HTTPMETHOD
@@ -55,7 +58,7 @@ from lib.core.exception import SqlmapUserQuitException
 from lib.core.settings import FORMAT_EXCEPTION_STRINGS
 from lib.core.settings import HEURISTIC_CHECK_ALPHABET
 from lib.core.settings import SUHOSIN_MAX_VALUE_LENGTH
-from lib.core.settings import UNKNOWN_DBMS_VERSION
+from lib.core.settings import UNKNOWN_DBMS
 from lib.core.settings import LOWER_RATIO_BOUND
 from lib.core.settings import UPPER_RATIO_BOUND
 from lib.core.settings import IDS_WAF_CHECK_PAYLOAD
@@ -441,11 +444,17 @@ def checkSqlInjection(place, parameter, value):
                             configUnion(test.request.char, test.request.columns)
 
                             if not Backend.getIdentifiedDbms():
-                                warnMsg = "using unescaped version of the test "
-                                warnMsg += "because of zero knowledge of the "
-                                warnMsg += "back-end DBMS. You can try to "
-                                warnMsg += "explicitly set it using option '--dbms'"
-                                singleTimeWarnMessage(warnMsg)
+                                if not kb.heuristicDbms:
+                                    kb.heuristicDbms = heuristicCheckDbms(injection) or UNKNOWN_DBMS
+
+                                if kb.heuristicDbms == UNKNOWN_DBMS:
+                                    warnMsg = "using unescaped version of the test "
+                                    warnMsg += "because of zero knowledge of the "
+                                    warnMsg += "back-end DBMS. You can try to "
+                                    warnMsg += "explicitly set it using option '--dbms'"
+                                    singleTimeWarnMessage(warnMsg)
+                                else:
+                                    Backend.forceDbms(kb.heuristicDbms)
 
                             if unionExtended:
                                 infoMsg = "automatically extending ranges "
@@ -582,6 +591,32 @@ def checkSqlInjection(place, parameter, value):
 
     return injection
 
+def heuristicCheckDbms(injection):
+    retVal = None
+
+    if not Backend.getIdentifiedDbms() and len(injection.data) == 1 and PAYLOAD.TECHNIQUE.BOOLEAN in injection.data:
+        pushValue(kb.injection)
+        kb.injection = injection
+        randStr1, randStr2 = randomStr(), randomStr()
+
+        for dbms in getPublicTypeMembers(DBMS, True):
+            Backend.forceDbms(dbms)
+
+            if checkBooleanExpression("(SELECT '%s'%s)='%s'" % (randStr1, FROM_DUMMY_TABLE.get(dbms, ""), randStr1)):
+                if not checkBooleanExpression("(SELECT '%s'%s)='%s'" % (randStr1, FROM_DUMMY_TABLE.get(dbms, ""), randStr2)):
+                    retVal = dbms
+                    break
+
+        Backend.flushForcedDbms()
+        kb.injection = popValue()
+
+    if retVal:
+        infoMsg = "heuristic test showed that the back-end DBMS "
+        infoMsg += "could be '%s' " % retVal
+        logger.info(infoMsg)
+
+    return retVal
+
 def checkFalsePositives(injection):
     """
     Checks for false positives (only in single special cases)
@@ -723,7 +758,7 @@ def heuristicCheckSqlInjection(place, parameter):
             kb.ignoreCasted = readInput(message, default='Y' if conf.multipleTargets else 'N').upper() != 'N'
 
     elif result:
-        infoMsg += "be injectable (possible DBMS: %s)" % (Format.getErrorParsedDBMSes() or UNKNOWN_DBMS_VERSION)
+        infoMsg += "be injectable (possible DBMS: %s)" % (Format.getErrorParsedDBMSes() or UNKNOWN_DBMS)
         logger.info(infoMsg)
 
     else:
diff --git a/lib/core/common.py b/lib/core/common.py
index 141eda6b4..9d19ff8b9 100644
--- a/lib/core/common.py
+++ b/lib/core/common.py
@@ -122,6 +122,7 @@ from lib.core.settings import SUPPORTED_DBMS
 from lib.core.settings import TEXT_TAG_REGEX
 from lib.core.settings import TIME_STDEV_COEFF
 from lib.core.settings import UNICODE_ENCODING
+from lib.core.settings import UNKNOWN_DBMS
 from lib.core.settings import UNKNOWN_DBMS_VERSION
 from lib.core.settings import URI_QUESTION_MARKER
 from lib.core.settings import URLENCODE_CHAR_LIMIT
diff --git a/lib/core/option.py b/lib/core/option.py
index 90831b0c4..39476b559 100644
--- a/lib/core/option.py
+++ b/lib/core/option.py
@@ -1526,6 +1526,7 @@ def _setKnowledgeBaseAttributes(flushAll=True):
     kb.fileReadMode = False
     kb.forcedDbms = None
     kb.headersFp = {}
+    kb.heuristicDbms = None
     kb.heuristicTest = None
     kb.hintValue = None
     kb.htmlFp = []
diff --git a/lib/core/settings.py b/lib/core/settings.py
index 873880730..3edb4ecfd 100644
--- a/lib/core/settings.py
+++ b/lib/core/settings.py
@@ -36,7 +36,8 @@ UPPER_RATIO_BOUND = 0.98
 # Markers for special cases when parameter values contain html encoded characters
 PARAMETER_AMP_MARKER = "__AMP__"
 PARAMETER_SEMICOLON_MARKER = "__SEMICOLON__"
-PARTIAL_VALUE_MARKER = "__PARTIAL__"
+PARTIAL_VALUE_MARKER = "__PARTIAL_VALUE__"
+PARTIAL_HEX_VALUE_MARKER = "__PARTIAL_HEX_VALUE__"
 URI_QUESTION_MARKER = "__QUESTION_MARK__"
 ASTERISK_MARKER = "__ASTERISK_MARK__"
 
@@ -111,6 +112,9 @@ INFERENCE_EQUALS_CHAR = "="
 # Character used for operation "not-equals" in inference
 INFERENCE_NOT_EQUALS_CHAR = "!="
 
+# String used for representation of unknown dbms
+UNKNOWN_DBMS = "Unknown"
+
 # String used for representation of unknown dbms version
 UNKNOWN_DBMS_VERSION = "Unknown"
 
@@ -459,7 +463,7 @@ VALID_TIME_CHARS_RUN_THRESHOLD = 100
 CHECK_ZERO_COLUMNS_THRESHOLD = 10
 
 # Boldify all logger messages containing these "patterns"
-BOLD_PATTERNS = ("' injectable", "might be injectable", "' is vulnerable", "is not injectable", "test failed", "test passed", "live test final result")
+BOLD_PATTERNS = ("' injectable", "might be injectable", "' is vulnerable", "is not injectable", "test failed", "test passed", "live test final result", "heuristic test showed")
 
 # Generic www root directory names
 GENERIC_DOC_ROOT_DIRECTORY_NAMES = ("htdocs", "wwwroot", "www")
diff --git a/lib/request/connect.py b/lib/request/connect.py
index 1394fc49e..e2ea2ac3e 100644
--- a/lib/request/connect.py
+++ b/lib/request/connect.py
@@ -687,7 +687,7 @@ class Connect(object):
         else:
             uri = conf.url
 
-        if place == PLACE.CUSTOM_HEADER:
+        if value and place == PLACE.CUSTOM_HEADER:
             if not auxHeaders:
                 auxHeaders = {}
             auxHeaders[value.split(',')[0]] = value.split(',', 1)[1]
diff --git a/lib/techniques/blind/inference.py b/lib/techniques/blind/inference.py
index ab0dbcc98..0fd592662 100644
--- a/lib/techniques/blind/inference.py
+++ b/lib/techniques/blind/inference.py
@@ -42,6 +42,7 @@ from lib.core.settings import INFERENCE_GREATER_CHAR
 from lib.core.settings import INFERENCE_EQUALS_CHAR
 from lib.core.settings import INFERENCE_NOT_EQUALS_CHAR
 from lib.core.settings import MAX_TIME_REVALIDATION_STEPS
+from lib.core.settings import PARTIAL_HEX_VALUE_MARKER
 from lib.core.settings import PARTIAL_VALUE_MARKER
 from lib.core.settings import VALID_TIME_CHARS_RUN_THRESHOLD
 from lib.core.threads import getCurrentThreadData
@@ -65,10 +66,17 @@ def bisection(payload, expression, length=None, charsetType=None, firstChar=None
     retVal = hashDBRetrieve(expression, checkConf=True)
 
     if retVal:
-        if PARTIAL_VALUE_MARKER in retVal:
+        if PARTIAL_HEX_VALUE_MARKER in retVal:
+            retVal = retVal.replace(PARTIAL_HEX_VALUE_MARKER, "")
+
+            if retVal and conf.hexConvert:
+                partialValue = retVal
+                infoMsg = "resuming partial value: %s" % safecharencode(partialValue)
+                logger.info(infoMsg)
+        elif PARTIAL_VALUE_MARKER in retVal:
             retVal = retVal.replace(PARTIAL_VALUE_MARKER, "")
 
-            if retVal:
+            if retVal and not conf.hexConvert:
                 partialValue = retVal
                 infoMsg = "resuming partial value: %s" % safecharencode(partialValue)
                 logger.info(infoMsg)
@@ -545,7 +553,7 @@ def bisection(payload, expression, length=None, charsetType=None, firstChar=None
             finalValue = decodeHexValue(finalValue) if conf.hexConvert else finalValue
             hashDBWrite(expression, finalValue)
         elif partialValue:
-            hashDBWrite(expression, "%s%s" % (PARTIAL_VALUE_MARKER, partialValue))
+            hashDBWrite(expression, "%s%s" % (PARTIAL_VALUE_MARKER if not conf.hexConvert else PARTIAL_HEX_VALUE_MARKER, partialValue))
 
     if conf.hexConvert and not abortedFlag:
         infoMsg = "\r[%s] [INFO] retrieved: %s  %s\n" % (time.strftime("%X"), filterControlChars(finalValue), " " * retrievedLength)
diff --git a/xml/livetests.xml b/xml/livetests.xml
index 115b738d7..455e1da55 100644
--- a/xml/livetests.xml
+++ b/xml/livetests.xml
@@ -3354,6 +3354,41 @@
             <item value="r'performed 112 queries'" console_output="True"/>
         </parse>
     </case>
+    <case name="Custom GET parameter injection mark">
+        <switches>
+            <verbose value="2"/>
+            <url value="http://debiandev/sqlmap/mysql/get_int.php?id=1*"/>
+            <tech value="B"/>
+            <getBanner value="True"/>
+        </switches>
+        <parse>
+            <item value="banner:    '5.1.66-0+squeeze1'"/>
+        </parse>
+    </case>
+    <case name="Custom POST data injection mark">
+        <switches>
+            <verbose value="2"/>
+            <url value="http://debiandev/sqlmap/mysql/post_int.php"/>
+            <data value="id=1*"/>
+            <tech value="E"/>
+            <getBanner value="True"/>
+        </switches>
+        <parse>
+            <item value="banner:    '5.1.66-0+squeeze1'"/>
+        </parse>
+    </case>
+    <case name="Custom HTTP header (UA) injection mark">
+        <switches>
+            <verbose value="2"/>
+            <url value="http://debiandev/sqlmap/mysql/header_str.php"/>
+            <headers value="User-Agent: 1*"/>
+            <tech value="U"/>
+            <getBanner value="True"/>
+        </switches>
+        <parse>
+            <item value="banner:    '5.1.66-0+squeeze1'"/>
+        </parse>
+    </case>
     <case name="Estimated time of arrival">
         <switches>
             <verbose value="2"/>