Microsoft Defender for has some gnarly vulnerabilities chilling in its communication with the cloud. Courtesy of InfoGuard Labs, these issues have been thrust into the limelight, primed for post-breach attackers to hilariously bypass authentication, spoof data, and even sneak in malicious files as investigators scramble.
Authentication Playtime: The security door’s left swinging wide open because agent requests are interceptable without any teaser of a valid token in sight. It’s like placing a “Come on in, take whatever you like” sign on the front lawn.
Data Spoofing & File Mischief: Post-breach, sensitive info feels like it’s tagged for capture, and hackers get to casually toss in malicious files during investigations. Think of it as seasoning with chaos.
The Investigation Game:
Armed with Burp Suite and WinDbg, the experts were practically detectives cracking a code. Here’s how they sleuthed out the flaws:
Burp Suite: Tuned in to intercept and tweak network traffic like it was gossip at a party.
CertPinning Bypass: Memory patching via WinDbg, tweaking the CRYPT32!CertVerifyCertificateChainPolicy was the baller move.
EDR’s Nightmare Zone:
Such cruddy vulnerabilities could make EDR systems pretty useless, letting attackers waltz right by authentication and throw around data like confetti.
Severity & Wait List: Those in the know think these issues are “low severity” (uh-huh) and so far, not a peep about fixes until at least October 2025. That’s two years from when MSRC was first nudged in July 2025.
DFE’s Cloud Fumbles:
Turns out, DFE’s cloud interactions are ripe for exploitation and previous concerns haven’t exactly taken a hint to leave the party:
Agent Hijinks: DFE acts like it’s above checking Authorization tokens. Endpoints get agent requests like “Here’s a pass, ignore the details.”
Proof of Mayhem:
Custom Script Antics: Attackers use a Bond Deserialization trick to decode action payloads—not 007, sadly. They cozy up to Azure Blob URIs with SAS tokens lounging around unbothered for ages.
Need-to-Know Nuggets:
Registry Prying: Sly spies get their hands on machine and tenant IDs from the registry like they’re picking candy from a bowl, then parading as the agent. Investigations turn amusing when they serve up innocent-looking bad files.
EDR communications are tripping up and while these might get brushed off as minor, they’re highlighting some not-so-bright spots in the realm of digital security. Magic wand, anyone? It’s time to conjure some effective solutions before it all spirals further.
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