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TITLE:
Python FTP Server Library Security Bypass and Denial of Service
Vulnerabilities

SECUNIA ADVISORY ID:
SA42143

VERIFY ADVISORY:
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http://secunia.com/advisories/42143/
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https://ca.secunia.com/?page=viewadvisory&vuln_id=42143

RELEASE DATE:
2010-11-06

DISCUSS ADVISORY:
http://secunia.com/advisories/42143/#comments

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http://secunia.com/advisories/42143/

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DESCRIPTION:
Some vulnerabilities have been reported in Python FTP server library
(pyftplib), which can be exploited by malicious users to bypass
certain security restrictions, and by malicious users and malicious
people to cause a DoS (Denial of Service).

1) A race condition within the "__init__()" method of the FTPHandler
class when acquiring a peername can lead to an unexpected exception
being raised causing the process to crash.

2) The library does not properly check for the "l" permission when
processing FTP MLST commands, which can be exploited to bypass
intended restrictions and list the contents of directories.

3) A memory leak exists within the "on_dtp_close()" method of the
FTPHandler class when processing FTP QUIT commands during a data
transfer.

4) An error within the FTPHandler class when accepting a connection
can lead to unexpected exceptions being raised or unexpected types
being returned causing the process to crash.

This vulnerability is related to:
SA41279

SOLUTION:
Update to version 0.5.2.

PROVIDED AND/OR DISCOVERED BY:
1) Reported by bneijt  in a pyftplib bug report.
2, 3) Reported by billiejoex in a pyftplib bug report.
4) Reported by wentao.han and billiejoex in pyftplib bug reports.

ORIGINAL ADVISORY:
1) http://code.google.com/p/pyftpdlib/issues/detail?id=100
2) http://code.google.com/p/pyftpdlib/issues/detail?id=114
3) http://code.google.com/p/pyftpdlib/issues/detail?id=119
4) http://code.google.com/p/pyftpdlib/issues/detail?id=104
http://code.google.com/p/pyftpdlib/issues/detail?id=105

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DEEP LINKS:
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EXTENDED SOLUTION:
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EXPLOIT:
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