Selfhosted

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[–] xylogx@lemmy.world -1 points 8 months ago (10 children)

Signatures do not help if your distribution infra gets compromised. See Solarwinds and the more recent node.js incidents.

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[–] ShortN0te@lemmy.ml 2 points 8 months ago (8 children)

This is incorrect. If the update you download is compromised then the signature is invalid and the update fails.

To achieve a compromised update you either need to compromise the update infrastructure AND the key or the infratstructure AND exploit the local updater to accept the invalid or forged signature.

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[–] xylogx@lemmy.world 1 point 8 months ago (7 children)

If I can control your infra I can alter what is a valid signature. It has happened. It will happen again. Digital signatures are not sufficient by themselves to prevent supply chain risks. Depending on your threat model, you need to assume advanced adversaries will seek to gain a foothold in your environment by attacking your software supplier. in these types of attacks threat actors can and will take control over the distribution mechanisms deploying trojaned backdoors as part of legitimately signed updates. It is a complex problem and I highly encourage you to read the NIST guidance to understand just how deep the rabbit hole goes.

Cybersecurity Supply Chain Risk Management Practices for Systems and Organizations

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[–] ShortN0te@lemmy.ml 1 point 8 months ago (6 children)

No you cannot, the pub key either needs to be present on the updater or uses infrastructure that is not owned by you. Usually how most software suppliers are doing it the public key is supplied within the updater.

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[–] xylogx@lemmy.world 1 point 8 months ago (5 children)

Not sure how else to explain this. Look at the CISA bulletin on Shai-Hulud the attacker published valid and signed binaries that were installed by hundreds of users.

"CISA is releasing this Alert to provide guidance in response to a widespread software supply chain compromise involving the world’s largest JavaScript registry, npmjs.com. A self-replicating worm—publicly known as “Shai-Hulud”—has compromised over 500 packages.[i]

After gaining initial access, the malicious cyber actor deployed malware that scanned the environment for sensitive credentials. The cyber actor then targeted GitHub Personal Access Tokens (PATs) and application programming interface (API) keys for cloud services, including Amazon Web Services (AWS), Google Cloud Platform (GCP), and Microsoft Azure.[ii]

The malware then:

Exfiltrated the harvested credentials to an endpoint controlled by the actor.
Uploaded the credentials to a public repository named Shai-Hulud via the GitHub/user/repos API.
Leveraged an automated process to rapidly spread by authenticating to the npm registry as the compromised developer, injecting code into other packages, and publishing compromised versions to the registry.[iii]"

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[–] ShortN0te@lemmy.ml 1 point 8 months ago (4 children)

After gaining initial access, the malicious cyber actor deployed malware that scanned the environment for sensitive credentials.

So as I said, the keys got compromised. Thats what i said in the second post.

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[–] xylogx@lemmy.world 1 point 8 months ago (3 children)

What you said is the key infra needs to get compromise. I do not need to own the PKI that issued the certs, I just need the private key of the signer. And again, this is something that happens. A lot. A software publisher gets owned, then their account is used to distribute malware.

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[–] ShortN0te@lemmy.ml 1 point 8 months ago (2 children)

To achieve a compromised update you either need to compromise the update infrastructure AND the key or the infratstructure AND exploit the local updater to accept the invalid or forged signature.

As i said, to compromise a signature checked update over the internet you need to compromise both, the distributing infrastructure AND the key. With just either one its not possible. (Ignoring flaws in the code ofc)