Bugtraq mailing list archives

Dameware Passes Weak File Encryption Key in the Clear


From: ax09001h <ax09001h () hotmail com>
Date: 23 Mar 2004 20:17:10 -0000



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 WindowsÂ’ 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. 




Current thread: