Cisco also said that the hacker’s ability to install malicious firmware exists only for older company products. Newer ones are equipped with secure boot capabilities that prevent them from running unauthorized firmware, the company said.

To install their modified bootloader, the US and Japanese advisory said, the threat actors install an older version of the legitimate firmware and then modify it as it runs in memory. The technique overrides signature checks in the Cisco ROM monitor signature validation functions, specifically functions of Cisco’s IOS Image Load test and the Field Upgradeable ROMMON Integrity test. The modified firmware, which consists of a Cisco IOS loader that installs an embedded IOS image, allows the compromised routers to make connections over SSH without being recorded in event logs.

In an advisory of its own, Cisco said the threat actors are compromising the devices after acquiring administrative credentials and that there’s no indication they are exploiting vulnerabilities.

If they aren’t exploiting vulnerabilities (and this is all because of mishandling of admin creds) then why are only Cisco routers being targeted?

I suppose magic packets are not the packets for wake over lan, right? Because wol packages are commonly called magic packages too.

This is the best summary I could come up with:

The threat actor is somehow gaining administrator credentials to network devices used by subsidiaries and using that control to install malicious firmware that can be triggered with “magic packets” to perform specific tasks.

In an advisory of its own, Cisco said the threat actors are compromising the devices after acquiring administrative credentials and that there’s no indication they are exploiting vulnerabilities.

Cisco also said that the hacker’s ability to install malicious firmware exists only for older company products.

Newer ones are equipped with secure boot capabilities that prevent them from running unauthorized firmware, the company said.

BlackTech members use the modified firmware to override code in the legitimate firmware to add the SSH backdoor, bypass logging, and monitor incoming traffic for “magic packets.” The term refers to small chunks of data the attackers send to the infected routers.

While they appear random and innocuous in system logs, these packets allow the attackers to surreptitiously enable or disable the backdoor functionality.

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