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Microsoft Secure

Taking apart a double zero-day sample discovered in joint hunt with ESET

In late March 2018, I analyzed an interesting PDF sample found by ESET senior malware researcher Anton Cherepanov. The sample was initially reported to Microsoft as a potential exploit for an unknown Windows kernel vulnerability. During my investigation in parallel with ESET researchers, I was surprised to discover two new zero-day exploits in the same PDF....

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Now you see me: Exposing fileless malware

Attackers are determined to circumvent security defenses using increasingly sophisticated techniques. Fileless malware boosts the stealth and effectiveness of an attack, and two of last year’s major ransomware outbreaks (Petya and WannaCry) used fileless techniques as part of their kill chains. The idea behind fileless malware is simple: If tools already exist on a device...

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Detecting reflective DLL loading with Windows Defender ATP

Today’s attacks put emphasis on leaving little, if any, forensic evidence to maintain stealth and achieve persistence. Attackers use methods that allow exploits to stay resident within an exploited process or migrate to a long-lived process without ever creating or relying on a file on disk. In recent blogs we described how attackers use basic...

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