Detection rules › Sigma
Suspicious MSExchangeMailboxReplication ASPX Write
Detects suspicious activity in which the MSExchangeMailboxReplication process writes .asp and .apsx files to disk, which could be a sign of ProxyShell exploitation
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Initial Access | T1190 Exploit Public-Facing Application |
| Persistence | T1505.003 Server Software Component: Web Shell |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 11 | FileCreate |
Rule body yaml
title: Suspicious MSExchangeMailboxReplication ASPX Write
id: 7280c9f3-a5af-45d0-916a-bc01cb4151c9
status: test
description: Detects suspicious activity in which the MSExchangeMailboxReplication process writes .asp and .apsx files to disk, which could be a sign of ProxyShell exploitation
references:
- https://redcanary.com/blog/blackbyte-ransomware/
author: Florian Roth (Nextron Systems)
date: 2022-02-25
tags:
- attack.initial-access
- attack.t1190
- attack.persistence
- attack.t1505.003
logsource:
product: windows
category: file_event
detection:
selection:
Image|endswith: '\MSExchangeMailboxReplication.exe'
TargetFilename|endswith:
- '.aspx'
- '.asp'
condition: selection
falsepositives:
- Unknown
level: high
Stages and Predicates
Stage 0: condition
selectionStage 1: selection
selection:
Image|endswith: '\MSExchangeMailboxReplication.exe'
TargetFilename|endswith:
- '.aspx'
- '.asp'
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
Image | ends_with |
|
TargetFilename | ends_with |
|