Secure configuration of SMTP service
import smtplib
def send_email(from_addr, to_addr_list, cc_addr_list,
subject, message,
smtpserver='localhost', smtp_port=25, username='', password='',
isTls=True):
header = 'From: %s\\n' % from_addr
header += 'To: %s\\n' % ','.join(to_addr_list)
header += 'Cc: %s\\n' % ','.join(cc_addr_list)
header += 'Subject: %s\\n\\n' % subject
message = header + message
server = smtplib.SMTP(smtpserver, smtp_port)
server.starttls()
server.login(username,password)
problems = server.sendmail(from_addr, to_addr_list, message)
server.quit()
# Send an email
send_email('from@example.com', ['to@example.com'], ['cc@example.com'],
'Test Subject', 'Test Message',
smtpserver='smtp.example.com', smtp_port=25, username='user', password='password')
The above Python code uses the smtplib library to send an email from the specified 'from' address to the 'to' and 'cc' address lists with a defined subject and message. The SMTP server and port are defined in the
send_email function parameters, with the SMTP server defaulting to 'localhost' and the port defaulting to 25.
The vulnerability lies in the open SMTP port (25), which is used to send the email. This port is commonly used for mail delivery, but if not properly secured, it can be exploited by attackers to send emails using the web server. This could lead to a number of potential issues, including spamming, phishing, and server reputation damage.
Furthermore, the use of plain text for the username and password parameters in the
send_email function could potentially expose these sensitive details if the communication is intercepted. This is another security concern that should be addressed.
Finally, the
starttls() method is called to upgrade the insecure connection to a secure one, which encrypts the rest of the communication with the SMTP server. However, if the initial connection is intercepted before the
starttls() method is called, an attacker could potentially exploit this to perform a man-in-the-middle attack.
In conclusion, this code is vulnerable due to the open SMTP port and the potential exposure of sensitive details in the
send_email function. Proper security measures should be implemented to address these issues.
import smtplib
from smtplib import SMTP_SSL as SMTP
from email.mime.text import MIMEText
def send_email(from_addr, to_addr_list, cc_addr_list,
subject, message,
smtpserver='localhost', smtp_port=587, username='', password='',
isTls=True):
header = 'From: %s\\n' % from_addr
header += 'To: %s\\n' % ','.join(to_addr_list)
header += 'Cc: %s\\n' % ','.join(cc_addr_list)
header += 'Subject: %s\\n\\n' % subject
message = header + message
msg = MIMEText(message)
msg['Subject']= subject
msg['From'] = from_addr
server = SMTP(smtpserver)
server.login(username,password)
server.sendmail(from_addr, to_addr_list, msg.as_string())
server.quit()
# Send an email
send_email('from@example.com', ['to@example.com'], ['cc@example.com'],
'Test Subject', 'Test Message',
smtpserver='smtp.example.com', smtp_port=587, username='user', password='password')
The updated code now uses a secure SMTP connection (SMTP_SSL) and port 587, which is often used for secure email submission. The SMTP server now requires authentication before sending emails, which can prevent unauthorized users from sending emails using the server.
The
smtplib.SMTP is replaced with
smtplib.SMTP_SSL to use a secure SSL connection when sending emails. This can prevent attackers from intercepting the emails.
The
server.sendmail method is updated to send the
msg object, which is an instance of
MIMEText. This object represents the email as a MIME text object, which can include the email headers (From, To, Cc, Subject) and the email body.
The
server.login method is used to log in to the SMTP server using the provided username and password. This is done before sending the email, which ensures that only authorized users can send emails.
The
server.quit method is used to terminate the SMTP session after the email is sent. This is a good practice to free up system resources and to ensure that the SMTP server is not left open to potential abuse.