Dameware Mini Remote Control Sends a File Encryption Key as Clear Text
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SecurityTracker Alert ID: 1009557 |
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SecurityTracker URL: http://securitytracker.com/id/1009557
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CVE Reference:
GENERIC-MAP-NOMATCH
(Links to External Site)
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Date: Mar 26 2004
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Impact:
Disclosure of authentication information, Disclosure of system information, Disclosure of user information
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Exploit Included: Yes
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Version(s): 4.1.0.0
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Description:
A vulnerability was reported in Dameware Mini Remote Control. The software transmits an encryption key over the network in clear text.
It is reported that the software sends a Blowfish encryption key over the network without encryption. The 2nd to last string of 16 bytes prior to the file being transferred is reportedly the file encryption key.
It is also reported that the software uses an insufficiently random generator to create the encryption key, facilitating key cracking attacks.
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Impact:
A remote user monitoring the network between the two encryption endpoints can determine the encryption key and gain access to the transmitted file.
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Solution:
No solution was available at the time of this entry.
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Vendor URL: www.dameware.com/products/ (Links to External Site)
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Cause:
Access control error, Randomization error
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Underlying OS:
Windows (NT), Windows (2000), Windows (XP)
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Message History:
None.
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Source Message Contents
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Date: 23 Mar 2004 20:17:10 -0000
Subject: Dameware Passes Weak File Encryption Key in the Clear
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Dameware Mini Remote Control version 4.1.0.0 and presumably other versions pass a Blowfish encryption key over the wire in the clear.
It is bad enough that they appear to be using Blowfish in Electronic Codebook Mode; but they compound their errors by the following
two vulnerabilities.
The Dameware Mini Remote Control offers the capability to transfer files between the host and client encrypted using 128-bit Blowfish
Encryption. Their first mistake is using a poor random bit generator to create their encryption key. After identifying the key
in the clear I was able to surmise that the lack of cryptographic expertise of the Dameware developers was systemic and checked to
see if they were using the built-in rand() function to generate the key. It did not take long to exhaust the small space of the
Windows’ linear congruential generator (LCG) in rand() to discover the following hypothesized loop for generating their file encryption
key.
int i;
unsigned char dw_f_key[16];
srand(time(NULL));
for(i=0;i<16;i++){
dw_f_key[i] = rand();
}
The second major and more serious mistake is that they actually pass the file encryption key in the clear over the wire. This can
be seen by analyzing packets between host and target. In a packet just prior to the file being sent the second to the last string
of 16-bytes is the file encryption key.
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