Potential Compromised 3CXDesktopApp Execution

Status: test
Severity: high
Log source: product windows, category process_creation
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects execution of known compromised version of 3CXDesktopApp

MITRE ATT&CK coverage

Tactic	Techniques
Stealth	`T1218` System Binary Proxy Execution

Event coverage

Provider	Event	Title
Sysmon	Event ID 1	Process creation

Rule body yaml

title: Potential Compromised 3CXDesktopApp Execution
id: 93bbde78-dc86-4e73-9ffc-ff8a384ca89c
related:
    - id: 3c4b3bbf-36b4-470c-b6cf-f07e8b1c7e26 # Proxy C2
      type: similar
    - id: 76bc1601-9546-4b75-9419-06e0e8d10651 # Proxy GH
      type: similar
    - id: bd03a0dc-5d93-49eb-b2e8-2dfd268600f8 # DNS C2
      type: similar
    - id: 51eecf75-d069-43c7-9ea2-63f75499edd4 # net_connection C2
      type: similar
    - id: 63f3605b-979f-48c2-b7cc-7f90523fed88 # ProcCreation ChildProc
      type: similar
    - id: e7581747-1e44-4d4b-85a6-0db0b4a00f2a # ProcCreation Update
      type: similar
    - id: d0b65ad3-e945-435e-a7a9-438e62dd48e9 # ImageLoad
      type: similar
status: test
description: Detects execution of known compromised version of 3CXDesktopApp
references:
    - https://www.reddit.com/r/crowdstrike/comments/125r3uu/20230329_situational_awareness_crowdstrike/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-03-29
modified: 2024-11-23
tags:
    - attack.stealth
    - attack.t1218
    - attack.execution
    - detection.emerging-threats
logsource:
    category: process_creation
    product: windows
detection:
    selection_hashes:
        Hashes|contains:
            # 3CX Desktop 18.12.407
            - 'SHA256=DDE03348075512796241389DFEA5560C20A3D2A2EAC95C894E7BBED5E85A0ACC'
            - 'SHA256=54004DFAA48CA5FA91E3304FB99559A2395301C570026450882D6AAD89132A02'
            - 'SHA256=D45674F941BE3CCA2FBC1AF42778043CC18CD86D95A2ECB9E6F0E212ED4C74AE'
            - 'SHA1=480DC408EF50BE69EBCF84B95750F7E93A8A1859'
            - 'SHA1=3B43A5D8B83C637D00D769660D01333E88F5A187'
            - 'SHA1=6285FFB5F98D35CD98E78D48B63A05AF6E4E4DEA'
            - 'MD5=BB915073385DD16A846DFA318AFA3C19'
            - 'MD5=08D79E1FFFA244CC0DC61F7D2036ACA9'
            - 'MD5=4965EDF659753E3C05D800C6C8A23A7A'
            # 3CX Desktop 18.12.416
            - 'SHA256=FAD482DED2E25CE9E1DD3D3ECC3227AF714BDFBBDE04347DBC1B21D6A3670405'
            - 'SHA256=5D99EFA36F34AA6B43CD81E77544961C5C8D692C96059FEF92C2DF2624550734'
            - 'SHA256=A60A61BF844BC181D4540C9FAC53203250A982E7C3AD6153869F01E19CC36203'
            - 'SHA1=E272715737B51C01DC2BED0F0AEE2BF6FEEF25F1'
            - 'SHA1=8433A94AEDB6380AC8D4610AF643FB0E5220C5CB'
            - 'SHA1=413D9CBFCBF8D1E8304EAB0AA5484F5EEC5185F5'
            - 'MD5=9833A4779B69B38E3E51F04E395674C6'
            - 'MD5=704DB9184700481A56E5100FB56496CE'
            - 'MD5=8EE6802F085F7A9DF7E0303E65722DC0'
            # 3CXDesktopApp MSI
            - 'SHA256=AA124A4B4DF12B34E74EE7F6C683B2EBEC4CE9A8EDCF9BE345823B4FDCF5D868'
            - 'SHA256=59E1EDF4D82FAE4978E97512B0331B7EB21DD4B838B850BA46794D9C7A2C0983'
            - 'SHA1=BEA77D1E59CF18DCE22AD9A2FAD52948FD7A9EFA'
            - 'SHA1=BFECB8CE89A312D2EF4AFC64A63847AE11C6F69E'
            - 'MD5=F3D4144860CA10BA60F7EF4D176CC736'
            - 'MD5=0EEB1C0133EB4D571178B2D9D14CE3E9'
    selection_pe_1:
        - OriginalFileName: '3CXDesktopApp.exe'
        - Image|endswith: '\3CXDesktopApp.exe'
        - Product: '3CX Desktop App'
    selection_pe_2:
        FileVersion|contains: '18.12.'
    condition: all of selection_pe_* or selection_hashes
falsepositives:
    - Legitimate usage of 3CXDesktopApp
level: high

Stages and Predicates

Stage 0: `condition`

all of selection_pe_* or selection_hashes

Stage 1: `selection_pe_1`

selection_pe_1:
    - OriginalFileName: '3CXDesktopApp.exe'
    - Image|endswith: '\3CXDesktopApp.exe'
    - Product: '3CX Desktop App'

Stage 2: `selection_pe_2`

selection_pe_2:
    FileVersion|contains: '18.12.'

Stage 3: `selection_hashes`

selection_hashes:
    Hashes|contains:
        - 'SHA256=DDE03348075512796241389DFEA5560C20A3D2A2EAC95C894E7BBED5E85A0ACC'
        - 'SHA256=54004DFAA48CA5FA91E3304FB99559A2395301C570026450882D6AAD89132A02'
        - 'SHA256=D45674F941BE3CCA2FBC1AF42778043CC18CD86D95A2ECB9E6F0E212ED4C74AE'
        - 'SHA1=480DC408EF50BE69EBCF84B95750F7E93A8A1859'
        - 'SHA1=3B43A5D8B83C637D00D769660D01333E88F5A187'
        - 'SHA1=6285FFB5F98D35CD98E78D48B63A05AF6E4E4DEA'
        - 'MD5=BB915073385DD16A846DFA318AFA3C19'
        - 'MD5=08D79E1FFFA244CC0DC61F7D2036ACA9'
        - 'MD5=4965EDF659753E3C05D800C6C8A23A7A'
        - 'SHA256=FAD482DED2E25CE9E1DD3D3ECC3227AF714BDFBBDE04347DBC1B21D6A3670405'
        - 'SHA256=5D99EFA36F34AA6B43CD81E77544961C5C8D692C96059FEF92C2DF2624550734'
        - 'SHA256=A60A61BF844BC181D4540C9FAC53203250A982E7C3AD6153869F01E19CC36203'
        - 'SHA1=E272715737B51C01DC2BED0F0AEE2BF6FEEF25F1'
        - 'SHA1=8433A94AEDB6380AC8D4610AF643FB0E5220C5CB'
        - 'SHA1=413D9CBFCBF8D1E8304EAB0AA5484F5EEC5185F5'
        - 'MD5=9833A4779B69B38E3E51F04E395674C6'
        - 'MD5=704DB9184700481A56E5100FB56496CE'
        - 'MD5=8EE6802F085F7A9DF7E0303E65722DC0'
        - 'SHA256=AA124A4B4DF12B34E74EE7F6C683B2EBEC4CE9A8EDCF9BE345823B4FDCF5D868'
        - 'SHA256=59E1EDF4D82FAE4978E97512B0331B7EB21DD4B838B850BA46794D9C7A2C0983'
        - 'SHA1=BEA77D1E59CF18DCE22AD9A2FAD52948FD7A9EFA'
        - 'SHA1=BFECB8CE89A312D2EF4AFC64A63847AE11C6F69E'
        - 'MD5=F3D4144860CA10BA60F7EF4D176CC736'
        - 'MD5=0EEB1C0133EB4D571178B2D9D14CE3E9'

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
`FileVersion`	match	`18.12.`
`Hashes`	match	`MD5=08D79E1FFFA244CC0DC61F7D2036ACA9` `MD5=0EEB1C0133EB4D571178B2D9D14CE3E9` `MD5=4965EDF659753E3C05D800C6C8A23A7A` `MD5=704DB9184700481A56E5100FB56496CE` `MD5=8EE6802F085F7A9DF7E0303E65722DC0` `MD5=9833A4779B69B38E3E51F04E395674C6` `MD5=BB915073385DD16A846DFA318AFA3C19` `MD5=F3D4144860CA10BA60F7EF4D176CC736` `SHA1=3B43A5D8B83C637D00D769660D01333E88F5A187` `SHA1=413D9CBFCBF8D1E8304EAB0AA5484F5EEC5185F5` `SHA1=480DC408EF50BE69EBCF84B95750F7E93A8A1859` `SHA1=6285FFB5F98D35CD98E78D48B63A05AF6E4E4DEA` `SHA1=8433A94AEDB6380AC8D4610AF643FB0E5220C5CB` `SHA1=BEA77D1E59CF18DCE22AD9A2FAD52948FD7A9EFA` `SHA1=BFECB8CE89A312D2EF4AFC64A63847AE11C6F69E` `SHA1=E272715737B51C01DC2BED0F0AEE2BF6FEEF25F1` `SHA256=54004DFAA48CA5FA91E3304FB99559A2395301C570026450882D6AAD89132A02` `SHA256=59E1EDF4D82FAE4978E97512B0331B7EB21DD4B838B850BA46794D9C7A2C0983` `SHA256=5D99EFA36F34AA6B43CD81E77544961C5C8D692C96059FEF92C2DF2624550734` `SHA256=A60A61BF844BC181D4540C9FAC53203250A982E7C3AD6153869F01E19CC36203` `SHA256=AA124A4B4DF12B34E74EE7F6C683B2EBEC4CE9A8EDCF9BE345823B4FDCF5D868` `SHA256=D45674F941BE3CCA2FBC1AF42778043CC18CD86D95A2ECB9E6F0E212ED4C74AE` `SHA256=DDE03348075512796241389DFEA5560C20A3D2A2EAC95C894E7BBED5E85A0ACC` `SHA256=FAD482DED2E25CE9E1DD3D3ECC3227AF714BDFBBDE04347DBC1B21D6A3670405`
`Image`	ends_with	`\3CXDesktopApp.exe` corpus 2 (sigma 2)
`OriginalFileName`	eq	`3CXDesktopApp.exe` corpus 2 (sigma 1, splunk 1)
`Product`	eq	`3CX Desktop App`

`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 Compromised 3CXDesktopApp Execution

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: `condition`

Stage 1: `selection_pe_1`

Stage 2: `selection_pe_2`

Stage 3: `selection_hashes`

Indicators

Keyboard shortcuts

Search operators

Potential Compromised 3CXDesktopApp Execution

MITRE ATT&CK coverage

Event coverage

Rule body yaml

Stages and Predicates

Stage 0: condition

Stage 1: selection_pe_1

Stage 2: selection_pe_2

Stage 3: selection_hashes

Indicators

Stage 0: `condition`

Stage 1: `selection_pe_1`

Stage 2: `selection_pe_2`

Stage 3: `selection_hashes`