Cleartext Transmission of Sensitive Information in the imaplib Module
The Python module imaplib provides a number of functions for accessing
IMAP servers. However, the default behavior of the module does not provide
utilize secure connections. This means that data transmitted over the network,
including passwords, is sent in cleartext. This makes it possible for attackers
to intercept and read this data.
The Python module imaplib should only in a secure mannner to protect sensitive data when accessing IMAP servers.
Example
import getpass
import imaplib
M = imaplib.IMAP4()
M.login(getpass.getuser(), getpass.getpass())
M.select()
typ, data = M.search(None, 'ALL')
for num in data[0].split():
typ, data = M.fetch(num, '(RFC822)')
print('Message %s\n%s\n' % (num, data[0][1]))
M.close()
M.logout()
Remediation
If the IMAP protocol must be used and sensitive data will be transferred, it
is recommended to secure the connection using IMAP4_SSL class.
Alternatively, the starttls function can be used to enter a secure session.
import getpass
import imaplib
M = imaplib.IMAP4_SSL()
M.login(getpass.getuser(), getpass.getpass())
M.select()
typ, data = M.search(None, 'ALL')
for num in data[0].split():
typ, data = M.fetch(num, '(RFC822)')
print('Message %s\n%s\n' % (num, data[0][1]))
M.close()
M.logout()
False Positives
In the case of a false positive the rule can be suppressed. Simply add a
trailing or preceding comment line with either the rule ID (PY008) or
rule category name (cleartext_transmission).
- Using rule ID
- Using category name
import getpass
import imaplib
# suppress: PY008
M = imaplib.IMAP4()
# suppress: PY008
M.login(getpass.getuser(), getpass.getpass())
M.select()
typ, data = M.search(None, 'ALL')
for num in data[0].split():
typ, data = M.fetch(num, '(RFC822)')
print('Message %s\n%s\n' % (num, data[0][1]))
M.close()
M.logout()
import getpass
import imaplib
# suppress: cleartext_transmission
M = imaplib.IMAP4()
# suppress: cleartext_transmission
M.login(getpass.getuser(), getpass.getpass())
M.select()
typ, data = M.search(None, 'ALL')
for num in data[0].split():
typ, data = M.fetch(num, '(RFC822)')
print('Message %s\n%s\n' % (num, data[0][1]))
M.close()
M.logout()