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Orenosv HTTP/FTP Server Multiple Buffer Overflows
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SUMMARY
" <http://hp.vector.co.jp/authors/VA027031/orenosv/index_en.html> Orenosv
is a stable, reliable and efficient HTTP/FTP/FTPS server that can operate
24H/365D. Orenosp runs on Windows platforms (NT, 2000, XP and 2003) and
Linux x86."
Mutliple buffer overflows vulnerabilities were found in Orenosv's server.
DETAILS
Vulnerable Systems:
* Orenosv HTTP/FTP Server version 0.8.1
Immune Systems:
* Orenosv HTTP/FTP Server version 0.8.1a
Multiple FTP Commands Buffer Overflow Vulnerability:
These buffer overflow is triggered when the server receives a FTP
file/directory manipulation command with a filename that is 249 or 250
bytes long.
For 4-character FTP file/directory commands, 249-bytes filenames will
cause the overflow. Examples of 4-character FTP commands include LIST,
DELE, RETR etc.
For 3-character FTP commands, 250-bytes filenames will cause the
overflow. 3-character FTP commands include MKD, RMD, CWD, etc.
The server restricts the maximum length of each input line, hence using a
filename that is longer than 250 will not trigger the vulnerable function.
Reverse engineering the orenosv.exe file reveals that the problem lies in
the unbounded copy that occurs within the ftp_xlate_path(),
ftp_is_canonial() and os_fn_nativize() functions, as well as due to
several unsafe use of sprintf().
Exploitation is complicated by the fact that the buffer is limited to 250
bytes.
Orenosv runs in two separate processes.
(1) The monitoring process
(2) The server process
The monitoring process will restart the server process if it crashes due
to the overflow. On our test system, we were able to cause a DoS on the
server by sending the overflow buffer in quick successions to the server.
This causes both the server and monitor process to crash, thus preventing
any automatic restart.
Long SSI Command Buffer Overflow Vulnerability (cgissi.exe ):
Orenosv supports the use of SSI (.shtml). This supported is provided by
cgissi.exe. A buffer overflow vulnerability exists in cgissi.exe when
processing an overly long SSI command name. The overflow occurs in the
parse_cmd() function. In this function, a loop performs an unsafe copy of
the SSI command name to a local stack buffer. This copy loop is terminated
by the space character. Exploitation may be limited since the SSI command
name is limited to less than 128 bytes.
Disclosure Timeline:
* 26.04.05 - Vulnerability Discovered
* 28.04.05 - Initial Author Notification
* 29.04.05 - Initial Author Reply
* 01.05.05 - Author Provided Fix for Testing
* 01.05.05 - Informed Author that Overflow will still occur in
os_fn_nativize()
* 01.05.05 - Author Provided Another Fix for Testing
* 01.05.05 - Informed Author that Overflow will still occur due to
several unsafe sprintf()
* 05.05.05 - Author Provided Another Fix for Testing
* 05.05.05 - Informed Author of Potential Problem in STOU command
* 06.05.05 - Author Provided Auother Fix for Testing
* 07.05.05 - Author Released Patch
* 08.05.05 - Public Release
ADDITIONAL INFORMATION
The information has been provided by <mailto:chewkeong@security.org.sg>
Chew Keong TAN.
The original article can be found at:
<http://www.security.org.sg/vuln/orenosv081.html>
http://www.security.org.sg/vuln/orenosv081.html
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