Microsoft confirms April Windows updates cause backup failures
Microsoft has confirmed that the April 2026 security updates are causing failures in third-party backup applications using the psmounterex.sys driver.
Ops Pack
triage-ready iocs + detections
fresh
1
IOC Workbench
typed indicators with fast copy and export actions
3 total
uhttps://www.bleepingcomputer.com/news/microsoft/microsoft-confirms-backup-failures-caused-by-vulnerable-driver-block/
dpsmounterex.sys
dwww.bleepingcomputer.com
3 indicators staged for handoff.
2
Rule Studio
starter detections generated from this IOC set
2 formats
!Draft output: validate and tune before production rollout.
sigmadraft
title: AHackaday IOC starter detection
id: ahackaday-2026-05-04-microsoft-confirms-april-windows-updates-cause-backup-failures-ec35a0d2
description: IOC starter rule for Microsoft confirms April Windows updates cause backup failures
status: experimental
author: ahackaday
logsource:
product: network
detection:
selection_iocs:
- "https://www.bleepingcomputer.com/news/microsoft/microsoft-confirms-backup-failures-caused-by-vulnerable-driver-block/"
- "psmounterex.sys"
- "www.bleepingcomputer.com"
condition: selection_iocs
falsepositives:
- unknown
level: high
coverage
yaradraft
rule ahackaday_2026_05_04_microsoft_confirms_april_windows_updates_cause_backup_failures_ec35a0d2
{
meta:
description = "IOC starter for Microsoft confirms April Windows updates cause backup failures"
author = "ahackaday"
strings:
$ioc1 = "https://www.bleepingcomputer.com/news/microsoft/microsoft-confirms-backup-failures-caused-by-vulnerable-driver-block/" nocase
$ioc2 = "psmounterex.sys" nocase
$ioc3 = "www.bleepingcomputer.com" nocase
condition:
any of them
}
coverage
3
Response Tracks
fast operational tracks from this incident snapshot
4 tracks
source-backed 1 refs
audit trail / provenance3
Provenance
Claims tie surfaced fields back to sources, models, or heuristics.
- severity.upliftheuristicn/aCVE or advisory identifiers detected — floor raised to at least high.
- severity.upliftheuristicn/aActive exploitation / in-the-wild language detected — floor raised to at least high.
- severity.upliftheuristicn/aCombined zero-day/exploit + ransomware/mass-impact signals → critical.
What changed
Append-only revisions when ingest or analysts evolve the record.
No revision rows stored yet.
Sources
Curated May 04, 2026 by the ahackaday team./Sources verified./Brief grounded in 1 source.
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