Resolve datadog-agent kworker false positives #300
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Signed-off-by: egibs <20933572+egibs@users.noreply.github.com>
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Signed-off-by: egibs <20933572+egibs@users.noreply.github.com>
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Signed-off-by: Evan Gibler <20933572+egibs@users.noreply.github.com>
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Signed-off-by: Evan Gibler <20933572+egibs@users.noreply.github.com>
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The ignore_refs look more complicated than we usually have, so I just wanted to see if they could be made into non-regex form.
Also related: #306
It'd be nice if we had at least one sample to validate that we aren't breaking this query, but we can save that for another PR too.
rules/evasion/fake-process-name.yara
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| @@ -7,10 +6,14 @@ rule fake_kworker_val : critical { | |||
| hash_2023_Unix_Downloader_Rocke_6107 = "61075056b46d001e2e08f7e5de3fb9bfa2aabf8fb948c41c62666fd4fab1040f" | |||
| strings: | |||
| $kworker = /\[{0,1}kworker\/[\d:\]]{1,5}/ | |||
| $kworker2 = "kworker" fullword | |||
| $kworker2 = /\bkworker\b/ | |||
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just for my own education, what's the difference between \b and fullword?
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For the purposes I was using it for, probably not. It would definitely provide more control in a larger expression but I can change this back to "kworker" fullword.
rules/evasion/fake-process-name.yara
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| $kworker3 = "[kworker" | ||
| // datadog process-agent | ||
| $ignore_ref = /(data->|[!\*\.])?is_kworker(\.\w{0,32})?/ |
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Can these expressions be simplified? Is there a reason why a single string (non-regex) isn't sufficient to exclude datadog?
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Good point -- I was way overthinking this. I'll just ignore DataDog and datadog.
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Both DataDog and datadog were present so I used a small expression to cover both cases in ca4eff3 (#300).
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/bincapz # yara rules/evasion/fake-process-name.yara /usr/bin/process-agent -s
/bincapz # yara rules/evasion/fake-process-name.yara /usr/bin/process-agent -c
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Signed-off-by: egibs <20933572+egibs@users.noreply.github.com>
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* Resolve datadog-agent kworker false positives Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> * Better handling of ignore_ref Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> * Update rules/evasion/fake-process-name.yara Signed-off-by: Evan Gibler <20933572+egibs@users.noreply.github.com> * Update rules/evasion/fake-process-name.yara Signed-off-by: Evan Gibler <20933572+egibs@users.noreply.github.com> * Add more precise DataDog process-agent kworker references Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> * More specificity Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> * Consolidate ignores Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> * Ignore DataDog strings Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> --------- Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> Signed-off-by: Evan Gibler <20933572+egibs@users.noreply.github.com> Co-authored-by: Thomas Strömberg <t+github@chainguard.dev>
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* Resolve datadog-agent kworker false positives Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> * Better handling of ignore_ref Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> * Update rules/evasion/fake-process-name.yara Signed-off-by: Evan Gibler <20933572+egibs@users.noreply.github.com> * Update rules/evasion/fake-process-name.yara Signed-off-by: Evan Gibler <20933572+egibs@users.noreply.github.com> * Add more precise DataDog process-agent kworker references Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> * More specificity Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> * Consolidate ignores Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> * Ignore DataDog strings Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> --------- Signed-off-by: egibs <20933572+egibs@users.noreply.github.com> Signed-off-by: Evan Gibler <20933572+egibs@users.noreply.github.com> Co-authored-by: Thomas Strömberg <t+github@chainguard.dev>
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Closes: #288
"kworker" fullwordwas likely matching these strings inprocess-agent:is_kworkercheckworkerThis PR tweaks the
$kworker2string to match eitherkworkerorKworkerbetween word boundaries which will avoid matching against strings like those mentioned above and also adds explicit ignores foris_kworkerandcheckworker.Discovery:
These strings were also present:
MarkWorkerIsKworkerIsNotKworkerNotKworkerThe new rule should ignore these as well.