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taviso's profile
Tavis Ormandy
Tavis Ormandy
Tavis Ormandy
Verified account
@taviso

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Tavis OrmandyVerified account

@taviso

Vulnerability researcher at Google. This is a personal stream, opinions expressed are mine.

California
taviso.decsystem.org
Joined April 2008

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    1. Jason Geffner‏ @JasonGeffner Feb 18
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      Replying to @taviso @dwizzzleMSFT

      Yes but that requires the attacker to still have access to the target, which is often not the case.

      2 replies 0 retweets 1 like
    2. Jason Geffner‏ @JasonGeffner Feb 18
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      Replying to @JasonGeffner @taviso @dwizzzleMSFT

      Also gives the victim's defenders a chance to detect each re-compromise (assuming detectable). And gives the victim the chance to patch or otherwise mitigate between each re-compromise (assuming protectable).

      1 reply 0 retweets 0 likes
    3. Tavis Ormandy‏Verified account @taviso Feb 18
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      Replying to @JasonGeffner @dwizzzleMSFT

      That doesn't make any sense, attackers already need to avoid detection, and defenders can already reimage and patch or mitigate. This "persistence" thing just seems buzzwordy to me.

      1 reply 0 retweets 0 likes
    4. Jason Geffner‏ @JasonGeffner Feb 18
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      Replying to @taviso @dwizzzleMSFT

      Avoiding detection N times is harder than avoiding detection 1 time (especially with N spanning multiple days/weeks/months). An attacker who gets a persistent foothold can prevent patching or create another backdoor, but w/o persistence they need to keep recompromising.

      1 reply 0 retweets 1 like
    5. Tavis Ormandy‏Verified account @taviso Feb 18
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      Replying to @JasonGeffner @dwizzzleMSFT

      This still makes no sense. Unless you are proposing rolling hourly reboots, then you need to be detected before taking action and resetting to a known good state, right?

      1 reply 0 retweets 0 likes
    6. Jason Geffner‏ @JasonGeffner Feb 18
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      Replying to @taviso @dwizzzleMSFT

      Not proposing hourly reboots :) But some device classes (phones, for example) do get restarted more than others (old-school monolithic web servers).

      1 reply 0 retweets 0 likes
    7. Tavis Ormandy‏Verified account @taviso Feb 18
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      Replying to @JasonGeffner @dwizzzleMSFT

      Sure, perhaps weekly maybe daily at a stretch, isn't being compromised that long bad enough? I know I wouldn't feel much better if you told me an attacker had kernel code exec, but only for a few days!

      1 reply 0 retweets 0 likes
    8. Jason Geffner‏ @JasonGeffner Feb 18
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      Replying to @taviso @dwizzzleMSFT

      Depends on the attacker's objectives. If it's stealing your browser's current cookies then a few seconds is more than enough. But if objective is capturing conversations or waiting for corporate earnings numbers to become available then attacker needs to focus on long-term.

      1 reply 0 retweets 0 likes
    9. Tavis Ormandy‏Verified account @taviso Feb 18
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      Replying to @JasonGeffner @dwizzzleMSFT

      Right, this is an example of a minor change in approach - you recompromise after the phone is rebooted, or wait until you knew earnings are about to be released. Would you agree that lack of long term persistence does not prevent those two attacks?

      1 reply 0 retweets 0 likes
    10. Jason Geffner‏ @JasonGeffner Feb 18
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      Replying to @taviso @dwizzzleMSFT

      If attacker can recompromise at will without detection or prevention then persistence doesn't really matter anymore. But if attacker only gets a single chance to compromise victim and objective data is not yet on victim's device then persistence does matter.

      1 reply 0 retweets 0 likes
      Tavis Ormandy‏Verified account @taviso Feb 18
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      Replying to @JasonGeffner @dwizzzleMSFT

      In your opinion, is that a common issue? Attackers only having a single chance to compromise, and only want data that doesn't exist yet, and won't exist before the next normal reboot (let's say, a month for patch Tuesday) - and no other way to leverage a full compromise?

      6:51 PM - 18 Feb 2020
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      • Eyal Itkin
      1 reply 0 retweets 1 like
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        2. Jason Geffner‏ @JasonGeffner Feb 18
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          Replying to @taviso @dwizzzleMSFT

          Common enough in the APT space to make non-persistence a worthwhile defense-in-depth measure.

          1 reply 0 retweets 0 likes
        3. Tavis Ormandy‏Verified account @taviso Feb 18
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          Replying to @JasonGeffner @dwizzzleMSFT

          Hah, it was rhetorical, it's not common at all. This kind of minor inconvenience happens literally all the time, some patch breaks some technique - exploitation still continues, attackers simply adjust.

          1 reply 0 retweets 0 likes
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