Re: DRAM data persistence

On Jul 5, 11:29 am, n...@xxxxxxxxxxx (Nico Coesel) wrote:
MooseFET <kensm...@xxxxxxxxx> wrote:
On Jul 4, 11:27 am, n...@xxxxxxxxxxx (Nico Coesel) wrote:
Jan Panteltje <pNaonStpealm...@xxxxxxxxx> wrote:
On a sunny day (Wed, 04 Jul 2007 17:13:42 GMT) it happened n...@xxxxxxxxxxx
(Nico Coesel) wrote in <468bd3e8.1017820...@xxxxxxxxxxxxxx>:

You are qouting the C specification. This doesn't mean it is
implemented that way it just tells you you must expect rubbish. But
like I said, to be absolutely sure no data can be shared between
different tasks unintended, any data used by an application is cleared
(this does not necessarely mean made 0) by the OS before it is
returned to the memory allocation pool.

Well, maybe you should specify *what* OS you are talking about.

Any modern OS should do this.

I disagree. Clearing memory takes time. If speed is the issue, you
can save time by not clearing memory. Applications that handle secure
data can clear the memory before freeing it so applications have
control over the security issue.

Bad idea. Rule number one: never leave security to an application
programmer. There should be a seperate 'layer' which deals with
security (like a firewall).

In not a single program or even OS I know about is memory cleared or
as you state overwritten by some other value, _after_ an application ends.
An application, if indeed written in C, ends normally by executing exit():

Don't think C (there are other languages!) but think security where
each application should live in its own sand box. In the end the OS
gives and takes memory to an application. So its the OS which has the
last thing to say about what happens to the memory that was used by
the application.

The OS needs to keep overhead to a minimum. What you are suggesting
adds a bunch of overhead. In time critical applications, this is a
bad thing.

Depends on your application. If you are developing stuff that is
somehow connected to the outside world I'd rather invest in a faster
CPU than having to explain my customers why their system was
vulnerable to an attack. A lot of embedded hardware gets connected to
a network these days. This makes life a lot easier but it comes with a
huge amount of security issues which need to be addressed.

You are assuming that unlimited CPU power can be bought and that it
doesn't increase cost or power consuption. A simple bit of good
programming practice of clearing the secret stuff before giving the
memory back solves the security problems at much less cost in
performance.


.

Relevant Pages

  • Re: you are in an fs with millions of small files
    ... It also requires holding al the strings in memory rather than continuing ... - Some operations become more expensive -- as directories grow, the cost ... All this said -- FreeBSD works really well for me with large file counts, ... with applications, and when you are using more extreme file system ...
    (freebsd-current)
  • [UNIX] Linux Kernel binfmt_elf ELF Loader Privilege Escalation
    ... Get your security news from a reliable source. ... or in other words to execute a new program. ... One of the Linux format loaders is the ELF (Executable and Linkable ... of the memory map header in the binary image and the program ...
    (Securiteam)
  • [NEWS] Xbox 360 Hypervisor Privilege Escalation Vulnerability
    ... Get your security news from a reliable source. ... Xbox 360 Hypervisor Privilege Escalation Vulnerability ... access to memory and provides encryption and decryption services. ... to the syscall dispatcher, as illustrated below. ...
    (Securiteam)
  • Re: Executable Memory in a Driver
    ... >> criminal to expose users to the added bluescreen and security risk. ... In a language that can't access outside an array, ... that doesn't need to move memory. ... > desired in the compiler. ...
    (microsoft.public.development.device.drivers)
  • [NT] Microsoft DCOM RPC Race Condition (MS04-012)
    ... Get your security news from a reliable source. ... the way Microsoft Windows handles DCOM RPC requests. ... based DCOM activation requests has been prone to failure in the past. ... may be overwritten depending on the block the memory management supplies ...
    (Securiteam)
Quantcast