MosaicRegressor
MosaicRegressor (canonical Kaspersky framework + bootkit naming per Kaspersky GReAT October 5-7, 2020 Securelist canonical disclosure by Mark Lechtik + Igor Kuznetsov + Yury Parshin) is a multi-stage modular cyber-espionage framework with custom UEFI bootkit capability, operationally significant as the first publicly-known custom-built UEFI bootkit in the wild per Kaspersky canonical 2020 attribution (per Mark Lechtik: "Although UEFI attacks present wide opportunities to the threat actors, MosaicRegressor is the first publicly known case where a threat actor used a custom made, malicious UEFI firmware in the wild. Previously known attacks observed in the wild simply repurposed legitimate software (for instance, LoJax), making this the first in the wild attack leveraging a custom made UEFI bootkit")
active 2017-2019 per Kaspersky telemetry analysis with several dozen documented victims (diplomats + NGO members from Africa + Asia + Europe), all with some ties to North Korea, operationally consistent with intelligence- collection mission objectives focused on North Korea- related diplomatic and humanitarian activity targeting; attribution to Chinese-speaking actor with low confidence Winnti/APT41 umbrella connection per Kaspersky based on single C&C infrastructure overlap (103.82.52[.]18) with publicly-reported Winnti umbrella activity and Chinese/Korean code page character sequence indicators (0xA3, 0xBA - FULL-WIDTH COLON per CP936/ CP949), mixed Kaspersky attribution stance (press release stated campaign not linked with confidence to known APT actors while Securelist blog refined to Chinese-speaking actor with possible Winnti connections); signature Hacking Team VectorEDK 2015 leak source-code derivative provenance (rogue UEFI firmware images modified using leaked Hacking Team VectorEDK source code following July 2015 Hacking Team breach.
operationally significant example of leaked-offensive-capability- repurposing pattern)
DXE driver addition approach to UEFI modification (operationally distinct from sibling MoonBounce existing-firmware-component modification approach per industry comparative analysis)
multi-stage modular MosaicRegressor framework architecture (downloaders + intermediate loaders + components fetched on demand to conceal wider framework from analysis + BitsRegEx Kaspersky-named variant)
UEFI bootkit + spear-phishing dual infection vectors (UEFI bootkit observed in only minority of MosaicRegressor framework victims, operationally cluster-defining capability deployed only against highest-priority targets.
spear- phishing emails written in Russian for majority of infections per Kaspersky)
signature IntelUpdate.exe system startup folder dropper persistence mechanism (bootkit places IntelUpdate.exe in system startup folder which downloads and installs MosaicRegressor components; per Kaspersky: "The only way to fix the problem is by reflashing the motherboard")
multi-channel C2 capability (cURL HTTP/HTTPS + BITS interface + WinHTTP + public mail services, operationally designed so blocking one route would not stop framework)
Hacking Team-suggested USB- drive physical-access deployment vector (per leaked Hacking Team manual, attackers presumably needed physical access via USB drive)
Kaspersky Firmware Scanner technology integrated into Kaspersky products since beginning of 2019 operationally enabled subsequent MosaicRegressor discovery.
fills the 2nd UEFI/firmware bootkit cell in the curated corpus following CosmicStrand (1st), operationally preceding sibling MoonBounce + BlackLotus clusters, operationally significant as the canonical "first publicly-known custom UEFI bootkit in the wild" industry baseline reference point cited in subsequent MoonBounce (Kaspersky January 2022) + CosmicStrand (Kaspersky July 2022) + BlackLotus (ESET March 2023) + NSA BlackLotus mitigation guidance (June 2023) disclosures as comparative chronological reference.