Debian OpenSSL Predictable PRNG Toys
[Quote:]
On May 13th, 2008 the Debian project announced that Luciano Bello found an interesting vulnerability in the OpenSSL package they were distributing. The bug in question was caused by the removal of the following line of code from md_rand.c
MD_Update(&m,buf,j); [ .. ] MD_Update(&m,buf,j); /* purify complains */These lines were removed because they caused the Valgrind and Purify tools to produce warnings about the use of uninitialized data in any code that was linked to OpenSSL. You can see one such report to the OpenSSL team here. Removing this code has the side effect of crippling the seeding process for the OpenSSL PRNG. Instead of mixing in random data for the initial seed, the only “random” value that was used was the current process ID. On the Linux platform, the default maximum process ID is 32,768, resulting in a very small number of seed values being used for all PRNG operations.
This is what seperates a decent developer from a great one. A decent developer looks at the warnings his tools produce and fixes the code to remove the warnings, a great develeoper looks at the warnings his tools produce and deeply understands when not to fix them.
May 17th, 2008 at 9:09
see also here.