lunes, 16 de noviembre de 2015

Testeando UrlScan 3.1 para IIS 7.5

Instalación


El otro día estaba viendo algo UrlScan, es una herramienta free de Microsoft para analizar requests así protegerte de ataques SQL Injection o Script Injection de forma simple, definiendo parámetros y opciones en un archivo ini.

Bajé la versión de 64 bits de https://www.microsoft.com/en-us/download/details.aspx?id=5728

Leí la documentación de: https://support.microsoft.com/es-es/kb/326444

El .ini queda instalado por defecto en: C:\Windows\System32\inetsrv\urlscan\UrlScan.ini

(Mi .ini que usé lo dejé al final)

La carpeta con los Logs: C:\Windows\System32\inetsrv\urlscan\logs\ le dí permiso de escritura al usuario IIS. En IIS 6 darle permiso de escritura al usuario IIS_WPG, y para IIS 7 u superior dale permisos a IIS_IUSRS.

En mi caso sólo usaré un filtro global, pero si quieres aplicar el filtro sólo para un sitio web, debes registrar la DLL como filtro en Web Sites -> Properties -> ISAPI Filters como dice aquí.

Al final de la instalación, reinicié el IIS con la línea de comandos iisreset.

Pruebas


NOTA: Por cada cambio en el .ini recomiendan Reciclar el Pool del sitio probado para que tome el cambio, si embargo a veces me tomaba sin necesidad de esto.

Error tilde IIS

Para corregir este conocido error de IIS 7 y 8: Microsoft IIS tilde directory enumeration, debes ir a Inicio -> Ejecutar:

%windir%\system32\inetsrv\urlscan

Agregar en UrlScan.ini (no requiere reiniciar el servidor, si aplicar un IIS reset)

[DenyUrlSequences]
~ ; para corregir error Microsoft IIS tilde directory enumeration

NOTA: Si tienes instalado Acunetix para auditar la seguridad de tus sitios, este error de tilde lo detecta de una, pero con esta corrección deja de aparecer el error.

SQL INJECTION

Al probar con la URL que tiene un "intento" de SQL Injection:

http://misitio.cl/index.asp?select=1

Resultado: Error 404 con detalles



Resultado desde fuera del sitio: Error 404 sin detalles (este error daría si el UrlScan está en producción y queremos acceder desde afuera):



Como nota, el mismo error da cuando escribimos un "intento" de Script Injection:

http://misitio.cl/index.asp?title=<meta%20http-equiv="refresh"%20content="0;">

Logging


El log, en mi caso, urlscan.111615.log, (es 16-nov-2015) va quedando con las entradas bloqueadas y el string o secuencia inválida:

#Software: Microsoft UrlScan 3.1
#Version: 1.0
#Date: 2015-11-16 20:09:41
#Fields: Date Time c-ip s-siteid cs-method cs-uri x-action x-reason x-context cs-data x-control
2015-11-16 20:09:43 172.31.17.26 9 GET /index.asp?item=%3C Rejected disallowed+query+string+sequence query+string - <

Errores comunes

El log solo logea los títulos de las columnas

-Revisa el archivo ini, que no tengas un [Options] ya que en el ejemplo del mismo .ini dice [Options].

Yo tenía:

[Options]
RuleList=SQL Injection

Y debe ser sólo:

RuleList=SQL Injection

-Revisa que le hayas dado permisos de escritura a la carpeta log al usuario de IIS.

Conclusión


UrlScan es la solución para evitar andar programando en el código (IF request ("%, <, >, etc...) == "error") ya que sólo mediante configuración filtras todo lo malo .

Referencias



Anexo: Mi archivo ini


Mi .ini que usé es este. Notar que dejé ScanHeaders=Cookie para incluir que si se crea una Cookie, se validen los strings que tenga como valor:
[options]

UseAllowVerbs=1                ; If 1, use [AllowVerbs] section, else use the
                               ; [DenyVerbs] section.   The default is 1.

UseAllowExtensions=0           ; If 1, use [AllowExtensions] section, else
                               ; use the [DenyExtensions] section. The
                               ; default is 0.

NormalizeUrlBeforeScan=1       ; If 1, canonicalize URL before processing.
                               ; The default is 1.  Note that setting this
                               ; to 0 will make checks based on extensions,
                               ; and the URL unreliable and is therefore not
                               ; recommend other than for testing.

VerifyNormalization=1          ; If 1, canonicalize URL twice and reject
                               ; request if a change occurs.  The default
                               ; is 1.

AllowHighBitCharacters=0       ; If 1, allow high bit (ie. UTF8 or MBCS)
                               ; characters in URL.  The default is 0.

AllowDotInPath=0               ; If 1, allow dots that are not file
                               ; extensions. The default is 0. Note that
                               ; setting this property to 1 will make checks
                               ; based on extensions unreliable and is
                               ; therefore not recommended other than for
                               ; testing.

RemoveServerHeader=0           ; If 1, remove the 'Server' header from
                               ; response.  The default is 0.

EnableLogging=1                ; If 1, log UrlScan activity.  The
                               ; default is 1.  Changes to this property
                               ; will not take effect until UrlScan is
                               ; restarted.

PerProcessLogging=0            ; This property is deprecated for UrlScan
                               ; 3.0 and later.  UrlScan 3.0 and later can
                               ; safely log output from multiple processes
                               ; to the same log file.  Changes to this
                               ; property will not take effect until
                               ; UrlScan is restarted.

AllowLateScanning=0            ; If 1, then UrlScan will load as a low
                               ; priority filter.  The default is 0.  Note
                               ; that this setting should only be used in
                               ; the case where there another installed
                               ; filter is modifying the URL and you wish
                               ; to have UrlScan apply its rules to the
                               ; rewritten URL.  Changes to this property
                               ; will not take effect until UrlScan is
                               ; restarted.

PerDayLogging=1                ; If 1, UrlScan will produce a new log each
                               ; day with activity in the form
                               ; 'UrlScan.010101.log'. If 0, UrlScan will
                               ; log activity to urlscan.log.  The default
                               ; is 1.  Changes to this setting will not
                               ; take effect until UrlScan is restarted.

UseFastPathReject=0            ; If 1, then UrlScan will not use the
                               ; RejectResponseUrl.  On IIS versions less
                               ; than 6.0, this will also prevent IIS
                               ; from writing rejected requests to the
                               ; W3SVC log.  UrlScan will log rejected
                               ; requests regardless of this setting.  The
                               ; default is 0.

LogLongUrls=0                  ; This property is deprecated for UrlScan 3.0
                               ; and later. UrlScan 3.0 and later will
                               ; always include the complete URL in its log
                               ; file.

UnescapeQueryString=1          ; If 1, UrlScan will perform two passes on
                               ; each query string scan, once with the raw
                               ; query string and once after unescaping it.
                               ; If 0, UrlScan will only look at the raw
                               ; query string as sent by the client.  The
                               ; default is 1. Note that if this property is
                               ; set to 0, then checks based on the query
                               ; string will be unreliable.

;
; If UseFastPathReject is 0, then UrlScan will send
; rejected requests to the URL specified by RejectResponseUrl.
; If not specified, '/Rejected-by-UrlScan' will be used.
; Changes to this setting will not take effect until UrlScan
; is restarted.
;
; Note that setting "RejectResponseUrl=/~*" will put UrlScan into Logging
; Only Mode.  In this mode, UrlScan will process all requests per the
; config settings, but it will only log the results and not actually
; reject the requests.  This mode is useful for testing UrlScan settings
; on a production server without actually interrupting requests.
;

RejectResponseUrl=

;
; LoggingDirectory can be used to specify the directory where the
; log file will be created.  This value should be the absolute path
; (ie. c:\some\path).  If not specified, then UrlScan will create
; the log in the same directory where the UrlScan.dll file is located.
; Changes to this setting will not take effect until UrlScan is
; restarted.
;

LoggingDirectory=Logs

;
; If RemoveServerHeader is 0, then AlternateServerName can be
; used to specify a replacement for IIS's built in 'Server' header
;

AlternateServerName=

;
; UrlScan supports custom rules that can be applied in addition to the other
; checks and options specified in this configuration file.  Rules should be
; listed in a comma separated string in the RuleList property.  Each rule in
; the list corresponds to two sections in this configuration file, one
; containing the options for the rule, and one containing deny strings for
; the rule.
;
; Here is an example:
;
;   [Options]
;   RuleList=Rule1
;
;   [Rule1]
;   AppliesTo=.exe,.dll        ; A comma separated list of file extensions to
;                              ; which the rule applies.  If not specified,
;                              ; the rule will be applied to all requests.
;
;   DenyDataSection=Rule1 Data ; The name of the section containing the
;                              ; rule's deny strings
;
;   ScanURL=0                  ; If 1, the URL will be scanned for deny
;                              ; strings. The default is 0.
;
;   ScanAllRaw=0               ; If 1, then the raw request header data will
;                              ; be scanned for deny strings.  The default
;                              ; is 0.
;
;   ScanQueryString=0          ; If 1, the the query string will be scanned
;                              ; for deny strings.  The default is 0.  Note
;                              ; that if UnescapeQueryString=1 is set in the
;                              ; [Options] section, then two scans will be
;                              ; made of the query string, one with the raw
;                              ; query string and one with the query string
;                              ; unescaped.
;
;   ScanHeaders=               ; A comma separated list of request headers to
;                              ; be scanned for deny strings.  The default is
;                              ; no headers.
;
;   DenyUnescapedPercent=0     ; If 1, UrlScan will scan the specified part
;                              ; of the raw request for a % character that is
;                              ; not used as an escape sequence.  If found,
;                              ; the request will be rejected.  This check
;                              ; can be used with ScanQueryString=1,
;                              ; ScanAllRaw=1, or the list of ScanHeaders.
;                              ; The default is 0.  Note that if you want to
;                              ; deny non-escaped % characters in the URL,
;                              ; you can set VerifyNormalization=0 in the
;                              ; [Options] section and then add % as a
;                              ; [DenyUrlSequences] entry.
;
;   [Rule1 data]
;   string1
;   string2
;

RuleList=SQL Injection

[SQL Injection]
AppliesTo=.asp,.aspx
DenyDataSection=SQL Injection Strings
ScanUrl=0
ScanAllRaw=0
ScanQueryString=1
ScanHeaders=Cookie:


[SQL Injection Strings]
--
@ ; also catches @@
alter
cast
convert
create
declare
delete
drop
exec ; also catches execute
fetch
insert
kill
select

[RequestLimits]

;
; The entries in this section impose limits on the length
; of allowed parts of requests reaching the server.
;
; It is possible to impose a limit on the length of the
; value of a specific request header by prepending "Max-" to the
; name of the header.  For example, the following entry would
; impose a limit of 100 bytes to the value of the
; 'Content-Type' header:
;
;   Max-Content-Type=100
;
; Any headers not listed in this section will not be checked for
; length limits.
;
; There are 3 special case limits:
;
;   - MaxAllowedContentLength specifies the maximum allowed
;     numeric value of the Content-Length request header.  For
;     example, setting this to 1000 would cause any request
;     with a content length that exceeds 1000 to be rejected.
;     The default is 30000000.
;
;   - MaxUrl specifies the maximum length of the request URL,
;     not including the query string. The default is 260 (which
;     is equivalent to MAX_PATH).
;
;   - MaxQueryString specifies the maximum length of the query
;     string.  The default is 2048.
;

MaxAllowedContentLength=30000000
MaxUrl=260
MaxQueryString=2048

[AllowVerbs]

;
; The verbs (aka HTTP methods) listed here are those commonly
; processed by a typical IIS server.
;
; Note that these entries are effective if "UseAllowVerbs=1"
; is set in the [Options] section above.
;

GET
HEAD
POST

[DenyVerbs]

;
; The verbs (aka HTTP methods) listed here are used for publishing
; content to an IIS server via WebDAV.
;
; Note that these entries are effective if "UseAllowVerbs=0"
; is set in the [Options] section above.
;

PROPFIND
PROPPATCH
MKCOL
DELETE
PUT
COPY
MOVE
LOCK
UNLOCK
OPTIONS
SEARCH

[DenyHeaders]

;
; The following request headers alter processing of a
; request by causing the server to process the request
; as if it were intended to be a WebDAV request, instead
; of a request to retrieve a resource.
;

Translate:
If:
Lock-Token:
Transfer-Encoding:

[AllowExtensions]

;
; Extensions listed here are commonly used on a typical IIS server.
;
; Note that these entries are effective if "UseAllowExtensions=1"
; is set in the [Options] section above.
;

.htm
.html
.txt
.jpg
.jpeg
.gif

[DenyExtensions]

;
; Extensions listed here either run code directly on the server,
; are processed as scripts, or are static files that are
; generally not intended to be served out.
;
; Note that these entries are effective if "UseAllowExtensions=0"
; is set in the [Options] section above.
;
; Also note that ASP scripts are denied with the below
; settings.  If you wish to enable ASP, remove the
; following extensions from this list:
;    .asp
;    .cer
;    .cdx
;    .asa
;

; Deny executables that could run on the server
.exe
.bat
.cmd
.com

; Deny infrequently used scripts
.htw     ; Maps to webhits.dll, part of Index Server
.ida     ; Maps to idq.dll, part of Index Server
.idq     ; Maps to idq.dll, part of Index Server
.htr     ; Maps to ism.dll, a legacy administrative tool
.idc     ; Maps to httpodbc.dll, a legacy database access tool
.shtm    ; Maps to ssinc.dll, for Server Side Includes
.shtml   ; Maps to ssinc.dll, for Server Side Includes
.stm     ; Maps to ssinc.dll, for Server Side Includes
.printer ; Maps to msw3prt.dll, for Internet Printing Services

; Deny various static files
.ini     ; Configuration files
.log     ; Log files
.pol     ; Policy files
.dat     ; Configuration files
.config  ; Configuration files

[AlwaysAllowedUrls]
;
; URLs listed here will always be explicitly allowed by UrlScan
; and will bypass all UrlScan checks.  URLs must be listed
; with a leading '/' character.  For example:
;
;   /SampleURL.htm
;

[DenyUrlSequences]
;
; If any character sequences listed here appear in the URL for
; any request, that request will be rejected.
;

..  ; Don't allow directory traversals
./  ; Don't allow trailing dot on a directory name
\   ; Don't allow backslashes in URL
:   ; Don't allow alternate stream access
%   ; Don't allow escaping after normalization
&   ; Don't allow multiple CGI processes to run on a single request

[AlwaysAllowedQueryStrings]
;
; Query strings listed here will always be explicitly allowed by
; UrlScan and will bypass all query string based checks.
;


[DenyQueryStringSequences]
;
; If any character sequences listed here appear in the query
; string for any request, that request will be rejected.
;

<   ; Commonly used by script injection attacks
>   ; Commonly used by script injection attacks

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