3 ms·

Anyone know why they are using timestamps instead of /dev/random? Dont get me wrong,im glad they don't, its just kind of surprising as it seems like such a roo

Anyone know why they are using timestamps instead of /dev/random? Dont get me wrong,im glad they don't, its just kind of surprising as it seems like such a rookie mistake. Is there something i'm missing here or is it more a caseof people who know what they are doing don't chose a life of crime?

__alexander 2y ago
Rolling your own crypto is still a thing.
- mschuster91 2y ago
  If it works (reasonably) it works, and it throws wrenches into the gears of security researchers when the code isn't the usual, immediately recognizable S boxes and other patterns or library calls.
  - deleted 2y ago
    [deleted]
  - emmelaich 2y ago
    Might be a bit a paranoia about official crypto libs backdoors, too.
dherls 2y ago
Charitable, use of system level randomness primitives can be audited by antivirus/EDR.
- hassleblad23 2y ago
  I wonder at what point would the antivirus kick in. It doesn't require reading /dev/urandom for too long.
0cf8612b2e1e 2y ago
Even if the attackers used a fully broken since 1980s encryption-how many organizations have the expertise to dissect it? I assume that threat detection maintains a big fingerprint databases of tools associated with malware. Rolling your own tooling, rather than importing a known library, gives one less heuristic to trip detection.
- int0x29 2y ago
  They used this with the IVs mucked with: https://www.gnupg.org/software/libgcrypt/index.html https://www.gnupg.org/software/libgcrypt/index.html
Retr0id 2y ago
afaik the majority of ransomware does manage to use cryptography securely, so we only hear about decrypting like this when they fuck up. I don't think there's any good reason beyond the fact that they evidently don't know what they're doing.
econ 2y ago
In case the tool is used against them.
ulrikrasmussen 2y ago
My unqualified hunch: if they did that, then a mitigation against such malware could be for the OS to serve completely deterministic data from /dev/random for all but a select few processes which are a priori defined.
- zerd 2y ago
  You can do the same with time though, just return a predefined sequence of timestamps.
  - Retr0id 2y ago
    And from a "defensive" perspective, if you don't trust any single entropy source, the paranoid solution is to combine multiple sources together rather than to switch to another source. If it were me, I'd combine urandom (or equivalent), high-res timestamps, and clock jitter (sample the LSB of a fast clock at "fixed" intervals where the interval is a few orders of magnitude slower than the clock resolution), and hash them all together.

__alexander 2y ago

Rolling your own crypto is still a thing.

mschuster91 2y ago
If it works (reasonably) it works, and it throws wrenches into the gears of security researchers when the code isn't the usual, immediately recognizable S boxes and other patterns or library calls.
- deleted 2y ago
  [deleted]
- emmelaich 2y ago
  Might be a bit a paranoia about official crypto libs backdoors, too.

dherls 2y ago

Charitable, use of system level randomness primitives can be audited by antivirus/EDR.

hassleblad23 2y ago
I wonder at what point would the antivirus kick in. It doesn't require reading /dev/urandom for too long.

0cf8612b2e1e 2y ago

Even if the attackers used a fully broken since 1980s encryption-how many organizations have the expertise to dissect it? I assume that threat detection maintains a big fingerprint databases of tools associated with malware. Rolling your own tooling, rather than importing a known library, gives one less heuristic to trip detection.

int0x29 2y ago
They used this with the IVs mucked with: https://www.gnupg.org/software/libgcrypt/index.html https://www.gnupg.org/software/libgcrypt/index.html

Retr0id 2y ago

afaik the majority of ransomware does manage to use cryptography securely, so we only hear about decrypting like this when they fuck up. I don't think there's any good reason beyond the fact that they evidently don't know what they're doing.

econ 2y ago

In case the tool is used against them.

ulrikrasmussen 2y ago

My unqualified hunch: if they did that, then a mitigation against such malware could be for the OS to serve completely deterministic data from /dev/random for all but a select few processes which are a priori defined.

zerd 2y ago
You can do the same with time though, just return a predefined sequence of timestamps.
- Retr0id 2y ago
  And from a "defensive" perspective, if you don't trust any single entropy source, the paranoid solution is to combine multiple sources together rather than to switch to another source. If it were me, I'd combine urandom (or equivalent), high-res timestamps, and clock jitter (sample the LSB of a fast clock at "fixed" intervals where the interval is a few orders of magnitude slower than the clock resolution), and hash them all together.