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Old 03-18-2008, 03:54 PM   #1
neocontrol
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Registered: Jul 2005
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Nessus scan reveils weak ciphers


I'm new to this securing apache stuff. I have run a nessus scan against a server and it throws this at me.

Code:
Description :

The remote host supports the use of SSL ciphers that offer either weak
encryption or no encryption at all. 

See also :

http://www.openssl.org/docs/apps/ciphers.html

Solution :

Reconfigure the affected application if possible to avoid use of weak
ciphers. 

Risk factor : 

Medium / CVSS Base Score : 5.0
(CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:N)

Plugin output :

Here is the list of weak SSL ciphers supported by the remote server :

Low Strength Ciphers (< 56-bit key)
SSLv3
EXP-EDH-RSA-DES-CBC-SHA Kx=DH(512) Au=RSA Enc=DES(40) Mac=SHA1 export 
EXP-DES-CBC-SHA Kx=RSA(512) Au=RSA Enc=DES(40) Mac=SHA1 export 
EXP-RC2-CBC-MD5 Kx=RSA(512) Au=RSA Enc=RC2(40) Mac=MD5 export 
EXP-RC4-MD5 Kx=RSA(512) Au=RSA Enc=RC4(40) Mac=MD5 export 
TLSv1
EXP-EDH-RSA-DES-CBC-SHA Kx=DH(512) Au=RSA Enc=DES(40) Mac=SHA1 export 
EXP-DES-CBC-SHA Kx=RSA(512) Au=RSA Enc=DES(40) Mac=SHA1 export 
EXP-RC2-CBC-MD5 Kx=RSA(512) Au=RSA Enc=RC2(40) Mac=MD5 export 
EXP-RC4-MD5 Kx=RSA(512) Au=RSA Enc=RC4(40t=MD5 export 

The fields above are :

{OpenSSL ciphername}
Kx={key exchange}
Au={authentication}
Enc={symmetric encryption method}
Mac={message authentication code}
{export flag}
My apache ssl config has this line in it which I think i need to modify...

Code:
SSLCipherSuite ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:-LOW:-SSLv2:+EXP:+eNULL
Can anyone tell me what I need to make this remove the weak ones?
 
Old 03-18-2008, 05:26 PM   #2
unSpawn
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Quote:
Originally Posted by neocontrol View Post
Can anyone tell me what I need to make this remove the weak ones?
You're skipping one step. You should find out what weak and "export grade" ciphers are, why they are a hazard and if you can afford to live with that. Check the hint http://www.openssl.org/docs/apps/ciphers.html, http://httpd.apache.org/docs/2.2/mod...sslciphersuite and http://httpd.apache.org/docs/2.2/ssl...tml#onlystrong. I wonder what the difference is between 'ALL:!NULL:!ADH:!EXPORT40:!EXPORT56' and 'HIGH:MEDIUM:!ADH'?..
 
  


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