Potential Exploitation of RCE Vulnerability CVE-2025-33053

Status: experimental
Severity: high
Log source: product windows, category process_creation
Author: Swachchhanda Shrawan Poudel (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects potential exploitation of remote code execution vulnerability CVE-2025-33053 which involves unauthorized code execution via WebDAV through external control of file names or paths. The exploit abuses legitimate utilities like iediagcmd.exe or CustomShellHost.exe by manipulating their working directories to point to attacker-controlled WebDAV servers, causing them to execute malicious executables (like route.exe) from the WebDAV path instead of legitimate system binaries through Process.Start() search order manipulation.

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1218` System Binary Proxy Execution
Command & Control	`T1105` Ingress Tool Transfer

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Potential Exploitation of RCE Vulnerability CVE-2025-33053
id: abe06362-a5b9-4371-8724-ebd00cd48a04
related:
    - id: 9a2d8b3e-f5a1-4c68-9e21-7d9e1cf8a123
      type: similar
    - id: 04fc4b22-91a6-495a-879d-0144fec5ec03
      type: similar
status: experimental
description: |
    Detects potential exploitation of remote code execution vulnerability CVE-2025-33053
    which involves unauthorized code execution via WebDAV through external control of file names or paths.
    The exploit abuses legitimate utilities like iediagcmd.exe or CustomShellHost.exe  by manipulating
    their working directories to point to attacker-controlled WebDAV servers, causing them to execute
    malicious executables (like route.exe) from the WebDAV path instead of legitimate system binaries
    through Process.Start() search order manipulation.
references:
    - https://msrc.microsoft.com/update-guide/en-US/vulnerability/CVE-2025-33053
    - https://research.checkpoint.com/2025/stealth-falcon-zero-day/
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-06-13
tags:
    - attack.command-and-control
    - attack.execution
    - attack.stealth
    - attack.t1218
    - attack.lateral-movement
    - attack.t1105
    - detection.emerging-threats
    - cve.2025-33053
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage:
            - 'C:\Program Files\internet explorer\iediagcmd.exe'
            - 'C:\Windows\System32\CustomShellHost.exe'
    selection_child_current_dir:
        - CurrentDirectory|startswith: '\\\\'
        - CurrentDirectory|contains: '\DavWWWRoot\'
        - Image|contains: '\DavWWWRoot\'
        - Image|startswith: '\\\\'
    selection_child_img:
        Image|endswith:
            - '\route.exe'
            - '\netsh.exe'
            - '\makecab.exe'
            - '\dxdiag.exe'
            - '\ipconfig.exe'
            - '\explorer.exe'
    filter_main_system:
        Image|startswith:
            - 'C:\Windows\System32\'
            - 'C:\Windows\SysWOW64\'
    condition: all of selection_* and not 1 of filter_main_*
falsepositives:
    - Unknown
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_* and not 1 of filter_main_*

Stage 1: `selection_parent`

selection_parent:
    ParentImage:
        - 'C:\Program Files\internet explorer\iediagcmd.exe'
        - 'C:\Windows\System32\CustomShellHost.exe'

Stage 2: `selection_child_current_dir`

selection_child_current_dir:
    - CurrentDirectory|startswith: '\\\\'
    - CurrentDirectory|contains: '\DavWWWRoot\'
    - Image|contains: '\DavWWWRoot\'
    - Image|startswith: '\\\\'

Stage 3: `selection_child_img`

selection_child_img:
    Image|endswith:
        - '\route.exe'
        - '\netsh.exe'
        - '\makecab.exe'
        - '\dxdiag.exe'
        - '\ipconfig.exe'
        - '\explorer.exe'

Stage 4: `not filter_main_system`

filter_main_system:
    Image|startswith:
        - 'C:\Windows\System32\'
        - 'C:\Windows\SysWOW64\'

Exclusions

Top-level NOT(...) conjuncts: predicates this rule actively suppresses.

Field	Kind	Excluded values
`Image`	starts_with	`C:\Windows\SysWOW64\`
`Image`	starts_with	`C:\Windows\System32\`

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
`CurrentDirectory`	match	`\DavWWWRoot\`
`CurrentDirectory`	starts_with	`\\\\`
`Image`	ends_with	`\dxdiag.exe` corpus 2 (sigma 2) `\explorer.exe` corpus 14 (sigma 14) `\ipconfig.exe` corpus 5 (sigma 5) `\makecab.exe` corpus 5 (sigma 5) `\netsh.exe` corpus 28 (sigma 28) `\route.exe` corpus 3 (sigma 3)
`Image`	match	`\DavWWWRoot\` corpus 3 (sigma 3)
`Image`	starts_with	`\\\\` corpus 4 (sigma 4)
`ParentImage`	eq	`C:\Program Files\internet explorer\iediagcmd.exe` corpus 2 (sigma 1, elastic 1) `C:\Windows\System32\CustomShellHost.exe`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)

Potential Exploitation of RCE Vulnerability CVE-2025-33053

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_parent`

Stage 2: `selection_child_current_dir`

Stage 3: `selection_child_img`

Stage 4: `not filter_main_system`

Exclusions

Indicators

Keyboard shortcuts

Search operators

Potential Exploitation of RCE Vulnerability CVE-2025-33053

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_parent

Stage 2: selection_child_current_dir

Stage 3: selection_child_img

Stage 4: not filter_main_system

Exclusions

Indicators

Stage 0: `condition`

Stage 1: `selection_parent`

Stage 2: `selection_child_current_dir`

Stage 3: `selection_child_img`

Stage 4: `not filter_main_system`