This Week In Security: Android Exposes ADB, ShinyHunters Get Paid, Robot Dogs, And More

Google has patched an Android ADB bug in the May security patch set. If you have a Pixel phone you should already have the patches, and most other major manufacturers should be close behind. Unfortunately, the biggest risk from this patch will be to the vendors who are also the least likely to release timely – or any – security updates.

ADB, the Android Debug Bridge, is the main tool for installing apps during development and debugging apps while they’re running. It can also be used to side-load apps from a PC. While most normal users are unlikely to ever enable it, developers typically do and some power users might when jailbreaking a device or setting parameters not exposed in the Android UI. Debugging can be done locally via USB, or optionally over the network. To protect the device, the user must unlock the Android device and authorize each new debug agent.

Covered by Risky.Biz, a bug introduced in 2020, and present in every Android release since, allowed bypassing authorization entirely if network debugging was enabled and at least one connection had been made to the ADB service in the past. This happens because ADB compares the certificate of the incoming debug connection with the list of saved certificates. If the certificate type does not match — for instance supplying an Ed25519 certificate instead of a RSA certificate — ADB has been incorrectly handling the error code, and allowing the connection.

In most programming languages, false is considered zero, and true is considered anything not zero. The certificate API returns a 1 for a valid match, a zero for an invalid match, and a negative-one for a type mismatch. Negative one is not zero, so when treated as a boolean value, it becomes true.

To exploit the bug, ADB must be enabled in wireless mode, and there must be at least one trusted device in the ADB configuration. For the average user this is an unlikely combination, but for developers, the time to update is now.

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This Week In Security: Annoyed Researchers, Dangling DNS, And Hacks That Could Have Been Worse

The author of the BlueHammer exploit, which was released earlier this month and addressed in the last Patch Tuesday, continues to be annoyed with the responses from the Microsoft security research and vulnerability response team, and has released another Windows zero-day attack against Windows Defender.

The RedSun exploit targets a logic and timing error in Windows Defender, convincing it to install the target file in the system, instead of quarantining the file and protecting the system. Not, generally, what you would hope would happen.

Since the RedSun attack requires local access in the first place, it seems unlikely Microsoft will release an out-of-sequence patch for it, however with public code available, we can probably expect to see malware leveraging it to establish higher permissions on an infected system.

Releasing exploits out of spite feels like a return to the late 1990s, and I almost don’t hate it.

University Domains Hijacked

Reported in Bleeping Computer, a group tracked as “Hazy Hawk” has been hijacking unmaintained DNS records of universities and government institutions to serve ad click spam.

The attack seems simple and doesn’t even require compromising the actual institution, using dangling DNS “CNAME” records. A “CNAME” entry in DNS acts essentially as an alias, pointing one domain name at another, which can be used to provide content from an official domain that is hosted on a cloud service where the IP address of the service might change.

A DNS “A” (or “AAAA” if you speak IPv6) record points a hostname – like “foo.example.com” – to an IP address – like “1.1.1.1”. A “CNAME” record points a hostname to another hostname, like “foo.some_cloud_host.com”. Scanning “high value” domains (like Ivy League universities) for “CNAME” records which point to expired domains (or domains on cloud hosted providers which no longer exist) lets anyone able to register that domain (or create an account with the proper naming scheme on the cloud host) to post any content they wish, and still appear to be the original name.

At least 30 educational institutions have been impacted, along with several government agencies including the CDC.

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