[Owasp-testing] Threat Agent Factors in OWASP Risk Rating Methodology

R M kingthorin at hotmail.com
Thu Jul 13 11:55:27 UTC 2017

Spot on Chris!

From: Chris Cooper <chris.cooper at owasp.org>
Sent: July 12, 2017 8:40 PM
To: R M
Cc: owasp-testing at lists.owasp.org
Subject: Re: [Owasp-testing] Threat Agent Factors in OWASP Risk Rating Methodology

To me, this argument depends on whether we are rating risks or vulnerabilities (spoiler: this is a risk rating methodology).

Risks encompass vulnerabilities, but they also include the threat and impact. Because we are working with a particular threat (maybe worst-case-scenario), I think the existing system makes perfect sense. The more skilled the threat actor is, the higher the risk. We're not talking about how skilled a generic actor needs to be, we're talking about how skilled they are, and whether they are skilled enough. I think the former is irrelevant considering that the threat is already established.

If we were talking about how severe a vulnerability is, regardless of the threat or the business impact, then I see the point being made here. If we don't have a specific threat in mind, we should hinge on the ease of exploitation (which RRM includes within the vulnerability factors already). But I think this is a separate rating system, or reduced subset of RRM, not an indication that the RRM is incorrect.


On Wed, Jul 12, 2017 at 7:27 PM, R M <kingthorin at hotmail.com<mailto:kingthorin at hotmail.com>> wrote:

I've always interpreted this in completely the opposite manner. If Threat Agent goes towards the Likelihood part of the calculation a skilled individual should be of greater concern than an unskilled individual.
"Note that there may be multiple threat agents that can exploit a particular vulnerability, so it's usually best to use the worst-case scenario."

There has been lengthy discussion of this in the past as well, see this thread from Aug 2013: http://lists.owasp.org/pipermail/owasp-testing/2013-August/002177.html


Pichaya Morimoto pichaya at ieee.org<http://ieee.org>
Mon Jun 5 06:11:34 UTC 2017

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Hi guys,

It seems that the OWASP RMM formula is incorrect.

"Skill level
How technically skilled is this group of threat agents? Security
penetration skills (9), network and programming skills (6), advanced
computer user (5), some technical skills (3), no technical skills (1)"


If a vulnerability requires skilled threat actors.. that means it is
unlikely that the vulnerability can be exploited so the likelihood should
go down by the skill level factor.

In short, skill level = level of skills required to perform the attack.

9 Highly skilled required = low risk (1) because the flaw is limited by the
number of good attackers.
1 No technical skills required = high risk (9)  since everyone can attack
the vulnerability... it is likely that the vulnerability will be exploited
at any given time.

You can't say that if the attacker is so good than the risk of
vulnerability will get higher because
1. We are talking about the risk of a particular vulnerability, not the
risk of a threat agent here.
2. Also, you cannot limit the skill of the attackers that could exploit the
vulnerability as well (but yes, the intranet users are probably not as good
as attackers from the internet?).
3. The skill level is a subsection of likelihood factor not impact factor !
Do not confuse impact of skill levels and possibility of being attacked by
the attacker with a given skill level.

I hope this will be fixed ASAP to make it more reasonable with the risk
rating scenarios.
Many thanks.

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