It is interesting to note how some very crucial security vulnerabilities in software are found a little too late. For instance, Samba just announced that it has now patched a remote code execution exploit which was present in all versions of Samba between 3.0.x and 3.6.3. This essentially means that this vulnerability is at least five years old since Samba released the 3.0.25 version as back as 2007.
This remote code execution exploit would have enabled a potential attacker to execute code as ‘root’ user acting as one from some anonymous connection. Nonetheless, the good news are that the vulnerability has been found and patched by Samba.
The developers of Samba described this security flaw in the following words, ‘ The code generator for Samba’s remote procedure call (RPC) code contained an error which caused it to generate code containing a security flaw. This generated code is used in the parts of Samba that control marshalling and unmarshalling of RPC calls over the network. The flaw caused checks on the variable containing the length of an allocated array to be done independently from the checks on the variable used to allocate the memory for that array. As both these variables are controlled by the connecting client it makes it possible for a specially crafted RPC call to cause the server to execute arbitrary code.
As this does not require an authenticated connection it is the most serious vulnerability possible in a program, and users and vendors are encouraged to patch their Samba installations immediately.’
Samba has released three new security releases. These are for such versions of the software which are currently supported and you can find them here. Moreover, patches for older versions of Samba who have this exploit have also been made available here.