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bpo-43285 Make ftplib not trust the PASV response. #24838

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merged 2 commits into from
Mar 15, 2021

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@gpshead gpshead commented Mar 13, 2021

The IPv4 address value returned from the server in response to the PASV command
should not be trusted. This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to. This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

https://bugs.python.org/issue43285

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.
@gpshead gpshead added type-bug An unexpected behavior, bug, or error needs backport to 3.6 type-security A security issue needs backport to 3.9 only security fixes labels Mar 13, 2021
@gpshead gpshead requested a review from vstinner March 13, 2021 11:56
@gpshead gpshead self-assigned this Mar 13, 2021
@gpshead gpshead merged commit 0ab152c into python:master Mar 15, 2021
@miss-islington
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Thanks @gpshead for the PR 🌮🎉.. I'm working now to backport this PR to: 3.6, 3.7, 3.8, 3.9.
🐍🍒⛏🤖

miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Mar 15, 2021
bpo-43285: Make ftplib not trust the PASV response.

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True.
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
@bedevere-bot bedevere-bot removed the needs backport to 3.9 only security fixes label Mar 15, 2021
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GH-24880 is a backport of this pull request to the 3.9 branch.

@miss-islington
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Sorry, @gpshead, I could not cleanly backport this to 3.8 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 0ab152c6b5d95caa2dc1a30fa96e10258b5f188e 3.8

@miss-islington
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Sorry @gpshead, I had trouble checking out the 3.7 backport branch.
Please backport using cherry_picker on command line.
cherry_picker 0ab152c6b5d95caa2dc1a30fa96e10258b5f188e 3.7

@miss-islington
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Sorry, @gpshead, I could not cleanly backport this to 3.6 due to a conflict.
Please backport using cherry_picker on command line.
cherry_picker 0ab152c6b5d95caa2dc1a30fa96e10258b5f188e 3.6

gpshead added a commit to gpshead/cpython that referenced this pull request Mar 15, 2021
)

bpo-43285: Make ftplib not trust the PASV response.

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
@bedevere-bot
Copy link

GH-24881 is a backport of this pull request to the 3.8 branch.

miss-islington added a commit that referenced this pull request Mar 15, 2021
bpo-43285: Make ftplib not trust the PASV response.

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True.
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
gpshead added a commit that referenced this pull request Mar 15, 2021
…H-24881)

bpo-43285: Make ftplib not trust the PASV response.

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Mar 15, 2021
) (pythonGH-24881)

bpo-43285: Make ftplib not trust the PASV response.

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
miss-islington pushed a commit to miss-islington/cpython that referenced this pull request Mar 15, 2021
) (pythonGH-24881)

bpo-43285: Make ftplib not trust the PASV response.

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
ned-deily pushed a commit that referenced this pull request Mar 16, 2021
…H-24881) (GH-24882)

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)
ned-deily pushed a commit that referenced this pull request Mar 16, 2021
…H-24881) (GH-24883)

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)
gentoo-bot pushed a commit to gentoo/cpython that referenced this pull request Apr 3, 2021
) (pythonGH-24881) (pythonGH-24882)

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)

Rebased for Python 2.7 by Michał Górny <mgorny@gentoo.org>
rickprice added a commit to ActiveState/cpython that referenced this pull request Feb 8, 2024
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-24881) (pythonGH-24882)

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)
rickprice added a commit to ActiveState/cpython that referenced this pull request Feb 8, 2024
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-24881) (pythonGH-24882)

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)
rickprice added a commit to ActiveState/cpython that referenced this pull request Feb 13, 2024
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-24881) (pythonGH-24882)

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)
rickprice added a commit to ActiveState/cpython that referenced this pull request Feb 13, 2024
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-24881) (pythonGH-24882)

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)
rickprice added a commit to ActiveState/cpython that referenced this pull request Jun 26, 2024
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-24881) (pythonGH-24882)

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)
icanhasmath pushed a commit to ActiveState/cpython that referenced this pull request Jul 30, 2024
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-24881) (pythonGH-24882)

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)
icanhasmath pushed a commit to ActiveState/cpython that referenced this pull request Jul 30, 2024
[3.6] bpo-43285 Make ftplib not trust the PASV response. (pythonGH-24838) (G…

…H-24881) (pythonGH-24882)

The IPv4 address value returned from the server in response to the PASV command
should not be trusted.  This prevents a malicious FTP server from using the
response to probe IPv4 address and port combinations on the client network.

Instead of using the returned address, we use the IP address we're
already connected to.  This is the strategy other ftp clients adopted,
and matches the only strategy available for the modern IPv6 EPSV command
where the server response must return a port number and nothing else.

For the rare user who _wants_ this ugly behavior, set a `trust_server_pasv_ipv4_address`
attribute on your `ftplib.FTP` instance to True..
(cherry picked from commit 0ab152c)

Co-authored-by: Gregory P. Smith <greg@krypto.org>
(cherry picked from commit 664d1d1)
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5 participants