DrayTek VigorACS SI 1.3.0 File Write / LFI / File Upload

`DrayTek VigorACS SI ( <= 1.3.0)  
  
Vigor ACS-SI Edition is a Central Management System for DrayTek  
routers and firewalls,  
providing System Integrators or system administration personnel a  
real-time integrated  
monitoring, configuration and management platform.  
  
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2.1. Default http-auth username/password used for <ip>/ACSServer/*  
  
We found that most of the VigorACS SI deployments are using the  
default http authentication settings (acs/password). This is not so much  
a software vulnerability but more a configuration issue.  
  
  
2.2 Unauthenticated arbitrary file read/write functionality via  
UploadDownloadServlet  
  
The UploadDownloadServlet can be used to (read and) write files to the  
server directly. In addition, this functionality is accessible without  
having to provide the  
http authentication details (2.1).  
  
  
2.3. Path traversal and Local File Inclusion in the FileServlet  
  
The regular expression that is used to prevent this is not sufficient:  
it removes occurences of '../' (without the quotes). By providing input  
like '....//', the middle '../' will be removed, while the remainder  
equals to '../'. We could now use the FileServlet to access any file on  
the server:  
<ip>/ACSServer/FileServlet?f=....//....//....//....//....//....//....//etc/passwd  
  
  
2.4. Arbitrary file upload in <ip>/ACSServer/UploadFileServlet  
  
This servlet suffers from the same path traversal vulnerability as  
described in 2.2. You can POST data to this servlet to upload files  
into arbitrary  
locations:  
http://<ip>//ACSServer/UploadFileServlet?prefix=<URLENCODED('a&....//....//....//....//....//server/default/deploy/web.war/shell.jsp&a&a&a&a')>  
  
The UploadFileServlet will append '.cfg' to the given filename, this means files  
uploaded via this mechanism aren't directly of use by an attacker. However, when  
the payload is a ZIP archive, the vuln. in 2.5 (Local unzip functionality)  
can be used to unpack an otherwise benign file into an full-blown  
remote web-shell.  
  
  
2.5. Local unzip functionality  
  
The RPC server provides an unzip functionality (rpcmanager.UnZip) that can be  
invoked by using the AMF message broker (accessible via  
http://<ip>/ACSServer/messagebroker/amf). This functionality can be used  
to unzip any file on the file system like one that has been previously uploaded  
using the UploadFileServlet vuln.  
  
  
2.6. ACS runs as root  
  
The webservice is running as the root user.  
  
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Timetable:  
  
2014-09-26 : Vender released patches (private and unverified) to their customers  
2014-07-22 : Vendor states that most of the vulns. are patched  
2014-07-08 : Vendor notified customers with large deployments  
2014-06-30 : Response of Vendor  
2014-06-24 : Notified Vendor  
  
Researchers:  
Victor van der Veen ([email protected])  
Erik-Paul Dittmer ([email protected])  
  
  
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