malware

Downdelph S0134

Type: malware
Platform: Windows
Created: 31 May 2017
Last modified: 25 April 2025

Downdelph is a first-stage downloader written in Delphi that has been used by APT28 in rare instances between 2013 and 2015. [1]

TechniquesBottom 23%

Tactics32nd pct

Threat groupunranked

CampaignsNone recorded

Enterprise ATT&CK only. Any Mobile or ICS rows on the same ATT&CK page are not carried.

Downdelph MITRE reference S0134

Junk Data T1001.001 ↗

Downdelph inserts pseudo-random characters between each original character during encoding of C2 network requests, making it difficult to write signatures on them.2

Command and Controlno detection rules

Ingress Tool Transfer T1105 ↗

After downloading its main config file, Downdelph downloads multiple payloads from C2 servers.3

Command and Control131 detection rules

Bypass User Account Control T1548.002 ↗

Downdelph bypasses UAC to escalate privileges by using a custom “RedirectEXE” shim database.4

Privilege Escalation76 detection rules

Symmetric Cryptography T1573.001 ↗

Downdelph uses RC4 to encrypt C2 responses.5

Command and Controlno detection rules

DLL T1574.001 ↗

Downdelph uses search order hijacking of the Windows executable sysprep.exe to escalate privileges.6

Execution · Stealth112 detection rules

Standing S0134

Reach is how much of ATT&CK this malware touches. Coverage is how well defended each thing it does is, as a median per technique rather than a total — a total would just restate the reach. Each figure is ranked against all 825 ATT&CK software entries only where that population actually spreads. Where most of the population shares one value, a percentile would rank the tie instead of the entity, so the raw value is shown and no rank is claimed.

Reach

Techniques5Bottom 23%

23rd percentile · 77% of 825 ATT&CK software entries have more Enterprise techniques.

Tactics432nd pct

32nd percentile · 68% of 825 ATT&CK software entries have more tactics spanned.

Threat group161% tie · 22 values

61% of the population shares a single value across only 22 distinct values, so a percentile here would rank the tie, not the entity.

Campaigns085% tie · 8 values

85% of the population shares a single value across only 8 distinct values, so a percentile here would rank the tie, not the entity.

Coverage

Rules / technique76medTop 1%

99th percentile · 99% of 825 ATT&CK software entries have this many detection rules per technique or fewer.

Tests / technique7med62nd pct

62nd percentile · 62% of 825 ATT&CK software entries have this many atomic tests per technique or fewer.

Data comps / technique5med54% tie · 11 values

54% of the population shares a single value across only 11 distinct values, so a percentile here would rank the tie, not the entity.

Mitigations / technique2medTop 9%

91st percentile · 91% of 825 ATT&CK software entries have this many mitigations per technique or fewer.

5 of 8 axes carry an honest rank on this page. Coverage medians are taken across this malware’s 5 Enterprise techniques.

Range

Technique Campaign use over its cumulative rule count.

Campaigns · 0Sigma rules (cumulative) · 237Splunk ESCU (cumulative) · 81

Standing S0134

Select	Description	Category	Status	Event	OS	Product	MITRE ATT&CK	CVEs	Severity	Author	Created	Updated	ID	Refs
	Detects Windows Installer service (msiexec.exe) spawning "cmd" or "powershell"	Generic	test	process_creation	windows	Sysmon · WinEventLog Security	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control	-	medium	Teymur Kheirkhabarov (idea), Mangatas Tondang (rule), oscd.community	2020-10-13	2022-10-20	1e53dd56-8d83-4eb4-a43e-b790a05510aa
	This rule will looks any process with low privilege launching Windows Installer service (msiexec.exe (...)	Unsupported	unsupported	process_creation	windows	Sysmon · WinEventLog Security	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control	-	high	Teymur Kheirkhabarov (idea), Mangatas Tondang (rule), oscd.community	2020-10-13	—	078235c5-6ec5-48e7-94b2-f8b5474379ea
	Detects Windows Installer service (msiexec.exe) trying to install MSI packages with SYSTEM privilege	Generic	test	process_creation	windows	Sysmon · WinEventLog Security	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control	-	medium	Teymur Kheirkhabarov (idea), Mangatas Tondang (rule), oscd.community	2020-10-13	2024-12-01	cd951fdc-4b2f-47f5-ba99-a33bf61e3770
	Detects DNS queries made by "AppInstaller.EXE". (...)	Generic	test	dns	windows	Sysmon	Command and Control Ingress Tool Transfer	-	medium	frack113	2021-11-24	2023-11-09	7cff77e1-9663-46a3-8260-17f2e1aa9d0a
	Detects the execution of DLL side-loading malware used by threat group Emissary Panda aka APT27	Emerging	test	process_creation	windows	Sysmon · WinEventLog Security	Execution, Stealth Hijack Execution Flow DLL	-	critical	Florian Roth (Nextron Systems)	2018-09-03	2023-03-09	9aa01d62-7667-4d3b-acb8-8cb5103e2014
	Detects execution of GfxDownloadWrapper.exe with a URL as an argument to download file.	Generic	test	process_creation	windows	Sysmon · WinEventLog Security	Command and Control Ingress Tool Transfer	-	medium	Victor Sergeev, oscd.community	2020-10-09	2023-10-18	eee00933-a761-4cd0-be70-c42fe91731e7
	Detects potential DLL sideloading activity via the Aruba Networks Virtual Intranet Access "arubanets (...)	Generic	test	image_load	windows	Sysmon	Execution, Stealth Hijack Execution Flow DLL	-	high	Nasreddine Bencherchali (Nextron Systems)	2023-01-22	2023-03-15	90ae0469-0cee-4509-b67f-e5efcef040f7
	Detects file creation events linked to the Axios NPM supply chain compromise. (...)	Emerging	experimental	file_event	linux	Sysmon	Command and Control Ingress Tool Transfer Initial Access Supply Chain Compromise Compromise Software Supply Chain	-	high	Swachchhanda Shrawan Poudel (Nextron Systems)	2026-04-01	—	b7cb840c-11f6-47f7-b3ef-5524739c9077
	Detects file creation events linked to the Axios NPM supply chain compromise on macOS devices. (...)	Emerging	experimental	file_event	macos	-	Command and Control Ingress Tool Transfer Initial Access Supply Chain Compromise Compromise Software Supply Chain	-	high	Swachchhanda Shrawan Poudel (Nextron Systems)	2026-04-01	—	2db0458c-05c9-4069-a26f-77becd9c8c13
	Detects the Linux-specific execution chain of the plain-crypto-js malicious npm dependency by Axios NPM package, including payload download via curl and detached execution using nohup and python3. (...)	Emerging	experimental	process_creation	linux	Sysmon	Execution Command and Scripting Interpreter Unix Shell Python Command and Control Ingress Tool Transfer Initial Access Supply Chain Compromise Compromise Software Supply Chain	-	high	Swachchhanda Shrawan Poudel (Nextron Systems)	2026-04-01	—	0a23a62d-c5b3-468b-a072-25064a9a8c87
	Detects the macOS-specific execution chain of the plain-crypto-js malicious npm dependency in Axios NPM Package, including AppleScript execution via osascript, payload download, permission modification, execution, and cleanup.	Emerging	experimental	process_creation	macos	-	Execution Command and Scripting Interpreter AppleScript Unix Shell Command and Control Ingress Tool Transfer Initial Access Supply Chain Compromise Compromise Software Supply Chain	-	high	Swachchhanda Shrawan Poudel (Nextron Systems)	2026-04-01	—	a09ee860-31b3-4586-8a68-0ebd74ce0e5f
	Detects the specific Windows execution chain and process tree associated with the Axios NPM supply chain compromise. (...)	Emerging	experimental	process_creation	windows	Sysmon · WinEventLog Security	Execution Command and Scripting Interpreter Windows Command Shell Visual Basic Command and Control Ingress Tool Transfer Initial Access Supply Chain Compromise Compromise Software Supply Chain	-	high	Swachchhanda Shrawan Poudel (Nextron Systems)	2026-04-01	—	f6c27ecc-d890-4452-80e6-2e274a10e097
Splunk	The following analytic detects the use of `bitsadmin.exe` with the `transfer` parameter to download a remote object. (...)	Generic	stable	process_creation	windows	Sysmon · WinEventLog Security · CrowdStrike	Execution, Persistence, Stealth BITS Jobs Command and Control Ingress Tool Transfer	-	medium	Michael Haag, Sittikorn S	2021-03-30	2026-10-02	80630ff4-8e4c-11eb-aab5-acde48001122
	Detects execution of Chromium based browser in headless mode	Generic	test	process_creation	windows	Sysmon · WinEventLog Security	Stealth Hide Artifacts Hidden Window Command and Control Ingress Tool Transfer	-	low	Nasreddine Bencherchali (Nextron Systems)	2023-09-12	—	ef9dcfed-690c-4c5d-a9d1-482cd422225c
	Bypasses User Account Control using a fileless method	Generic	test	registry_set	windows	Sysmon · WinEventLog Security	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control	-	high	frack113	2022-01-05	2023-08-17	46dd5308-4572-4d12-aa43-8938f0184d4f
	Detects the setting of the environement variable "windir" to a non default value. (...)	Generic	test	registry_set	windows	Sysmon · WinEventLog Security	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control	-	high	frack113, Nextron Systems	2022-01-06	2024-01-30	724ea201-6514-4f38-9739-e5973c34f49a
	Detect commandline usage of Microsoft Connection Manager Profile Installer (cmstp.exe) to install sp (...)	Generic	test	process_creation	windows	Sysmon · WinEventLog Security	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control Stealth System Binary Proxy Execution CMSTP	-	high	E.M. Anhaus (originally from Atomic Blue Detections, Endgame), oscd.community	2019-10-24	2022-08-30	e66779cc-383e-4224-a3a4-267eeb585c40
	Identifies use of Fodhelper.exe to bypass User Account Control. (...)	Generic	test	process_creation	windows	Sysmon · WinEventLog Security	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control	-	high	E.M. Anhaus (originally from Atomic Blue Detections, Tony Lambert), oscd.community	2019-10-24	2021-11-27	7f741dcf-fc22-4759-87b4-9ae8376676a2
	Detects use of WSReset.exe to bypass User Account Control (UAC). (...)	Generic	test	process_creation	windows	Sysmon · WinEventLog Security	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control	-	high	E.M. Anhaus (originally from Atomic Blue Detections, Tony Lambert), oscd.community, Florian Roth	2019-10-24	2022-05-13	d797268e-28a9-49a7-b9a8-2f5039011c5c
Splunk	The following analytic detects the execution of curl commands with insecure flags within the Cisco Isovalent environment. (...)	Anomaly	stable	process_creation	-	Cisco	Command and Control Ingress Tool Transfer	-	medium	Bhavin Patel, Splunk	2026-01-05	2026-10-02	c16c4899-d3f7-461b-92c2-cc0ef5758855
Splunk	This analytic identifies the use of Chromium-based browsers (like Microsoft Edge) running in headless mode with the `--dump-dom` argument. (...)	Generic	stable	network_connection	-	Cisco NVM · Cisco	Execution Command and Scripting Interpreter Command and Control Ingress Tool Transfer	-	medium	Nasreddine Bencherchali, Splunk	2025-07-01	2026-09-22	cd0e816f-f67d-4dbe-a153-480b546e867e
Splunk	This analytic detects unexpected outbound network connections initiated by known webserver processes such as `httpd.exe`, `nginx.exe`, or `tomcat.exe` to common file sharing or public content hosting services like GitHub, Discord CDN, Transfer.sh, or Pastebin. (...)	Generic	stable	network_connection	-	Cisco NVM · Cisco	Initial Access Exploit Public-Facing Application Command and Control Ingress Tool Transfer	-	medium	Nasreddine Bencherchali, Splunk	2025-07-01	2026-09-22	1984f997-3b49-4d4b-a7e9-dc5dbf88370e
Splunk	The following analytic detects potential reverse shell activity by identifying connections involving ports commonly associated with remote access tools, shell listeners, or tunneling utilities. (...)	Anomaly	stable	firewall	-	Cisco Secure Firewall · Cisco	Execution Command and Scripting Interpreter PowerShell Command and Control Ingress Tool Transfer Command and Control Non-Standard Port Privilege Escalation, Stealth Process Injection Command and Control Remote Access Tools Lateral Movement Remote Services	-	medium	Nasreddine Bencherchali, Splunk	2025-04-03	2026-05-13	d85c05c8-42c0-4e4a-87e7-4e1bb3e844e3
Splunk	The following analytic detects outbound connections to commonly abused file sharing and pastebin-style hosting domains. (...)	Anomaly	stable	firewall	-	Cisco Secure Firewall · Cisco	Command and Control Application Layer Protocol Web Protocols Exfiltration Exfiltration Over Web Service Exfiltration to Cloud Storage Command and Control Ingress Tool Transfer Resource Development Obtain Capabilities Tool Command and Control Proxy External Proxy	-	medium	Nasreddine Bencherchali, Splunk	2025-04-03	2026-05-13	f7e5e792-d907-46c1-a58e-4ff974dc462a
Splunk	The following analytic detects file transfers flagged as malware that occurred over non-standard ports (other than 80 and 443). (...)	Anomaly	stable	firewall	-	Cisco Secure Firewall · Cisco	Command and Control Ingress Tool Transfer Command and Control Non-Standard Port	-	medium	Nasreddine Bencherchali, Splunk	2025-04-09	2026-09-22	f26445a8-a6a2-4855-bec0-0c39e52e5b8f
Splunk	The following analytic detects connections with a high Encrypted Visibility Engine (EVE) threat confidence score, indicating potentially malicious behavior within encrypted traffic. (...)	Anomaly	stable	firewall	-	Cisco Secure Firewall · Cisco	Command and Control Application Layer Protocol Web Protocols Command and Control Encrypted Channel Asymmetric Cryptography Exfiltration Exfiltration Over C2 Channel Command and Control Ingress Tool Transfer	-	medium	Nasreddine Bencherchali, Splunk	2025-04-03	2026-05-13	8c15183e-2e70-4db4-86c3-88f8d9129b66
Splunk	The following analytic detects file downloads that were classified as malware by Cisco Secure Firewall Threat Defense. (...)	Anomaly	stable	firewall	-	Cisco Secure Firewall · Cisco	Execution Exploitation for Client Execution Command and Control Ingress Tool Transfer	-	medium	Nasreddine Bencherchali, Splunk	2025-04-09	2026-09-22	3cc93f52-5aa6-4b7f-83b9-3430b1436813
Splunk	The following analytic detects repeated malware file downloads initiated by the same internal host (src) within a short time window. (...)	Anomaly	stable	firewall	-	Cisco Secure Firewall · Cisco	Command and Control Ingress Tool Transfer Stealth Obfuscated Files or Information	-	medium	Nasreddine Bencherchali, Splunk	2025-04-09	2026-09-22	aeff2bb5-3483-48d4-9be8-c8976194be1e
Splunk	This analytic identifies Snort intrusion signatures that have been triggered by ten or more distinct internal IP addresses within a one-hour window. (...)	Anomaly	stable	firewall	-	Cisco Secure Firewall · Cisco	Command and Control Ingress Tool Transfer Stealth Obfuscated Files or Information	-	medium	Nasreddine Bencherchali, Splunk	2025-04-16	2026-05-13	a4c76d0a-56b6-44be-814b-939746c4d406
Splunk	The following analytic detects outbound connections initiated by command-line tools such as curl or wget. (...)	Anomaly	stable	firewall	-	Cisco Secure Firewall · Cisco	Command and Control Application Layer Protocol Web Protocols Execution Command and Scripting Interpreter Command and Control Ingress Tool Transfer Execution, Persistence, Privilege Escalation Scheduled Task/Job Cron	-	medium	Nasreddine Bencherchali, Splunk	2025-04-03	2026-05-13	173a1cb9-1814-4128-a9dc-f29dade89957
	Various protocols maybe used to put data on the device for exfil or infil	Generic	test	authentication	-	Cisco AAA · Cisco	Collection Archive Collected Data Archive via Utility Collection Data Staged Command and Control Ingress Tool Transfer	-	low	Austin Clark	2019-08-12	2023-01-04	5e51acb2-bcbe-435b-99c6-0e3cd5e2aa59	-
	Detects UAC Bypass Attempt Using Microsoft Connection Manager Profile Installer Autoelevate-capable COM Objects (e.g. (...)	Generic	stable	process_creation	windows	Sysmon · WinEventLog Security	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control Stealth System Binary Proxy Execution CMSTP	-	high	Nik Seetharaman, Christian Burkard (Nextron Systems)	2019-07-31	2024-12-01	4b60e6f2-bf39-47b4-b4ea-398e33cfe253
	Detects a suspicious command line execution that includes an URL and AppData string in the command l (...)	Generic	test	process_creation	windows	Sysmon · WinEventLog Security	Execution Command and Scripting Interpreter PowerShell Windows Command Shell Command and Control Ingress Tool Transfer	-	medium	Florian Roth (Nextron Systems), Jonhnathan Ribeiro, oscd.community	2019-01-16	2021-11-27	1ac8666b-046f-4201-8aba-1951aaec03a3
	Detects creation of specific system DLL files that are usually not present on the system (or at least not in system directories) but may be loaded by legitimate processes. (...)	Generic	test	file_event	windows	Sysmon	Execution, Stealth Hijack Execution Flow DLL	CVE-2020-7315	medium	Nasreddine Bencherchali (Nextron Systems), fornotes	2022-12-01	2026-01-24	df6ecb8b-7822-4f4b-b412-08f524b4576c
	Detects the creation of a file named "WerFault.exe" or "wer.dll" in an uncommon folder, which could be a sign of WerFault DLL hijacking.	Generic	test	file_event	windows	Sysmon	Execution, Stealth Hijack Execution Flow DLL	-	medium	frack113	2022-05-09	2026-05-18	28a452f3-786c-4fd8-b8f2-bddbe9d616d1
	Adversaries can use curl to download payloads remotely and execute them. (...)	Generic	test	process_creation	windows	Sysmon · WinEventLog Security	Command and Control Ingress Tool Transfer Stealth System Binary Proxy Execution	-	high	Sreeman, Nasreddine Bencherchali (Nextron Systems)	2020-01-13	2024-03-05	21dd6d38-2b18-4453-9404-a0fe4a0cc288
Splunk	The following analytic detects the execution of the curl utility where the command line includes percent-encoded characters and explicit file output options (such as -o or --output). (...)	Anomaly	stable	process_creation	windows · linux	CrowdStrike · Sysmon · WinEventLog Security	Command and Control Ingress Tool Transfer Stealth Obfuscated Files or Information	-	medium	Nasreddine Bencherchali, Splunk	2026-03-03	2026-05-13	9a8d5516-4c5e-11ef-9d42-acde48001122
	Detects a curl process start on linux, which indicates a file download from a remote location or a s (...)	Generic	test	process_creation	linux	Sysmon	Command and Control Ingress Tool Transfer	-	low	Nasreddine Bencherchali (Nextron Systems)	2022-09-15	—	ea34fb97-e2c4-4afb-810f-785e4459b194
	Detects a curl process start on Windows, which could indicates a file download from a remote locatio (...)	Hunting	test	process_creation	windows	Sysmon · WinEventLog Security	Command and Control Ingress Tool Transfer	-	low	Florian Roth (Nextron Systems)	2022-07-05	2023-02-21	bbeaed61-1990-4773-bf57-b81dbad7db2d
	Detects the usage of curl.exe, KeyScramblerLogon, or other non-standard/suspicious processes used to create Autoit3.exe. (...)	Emerging	test	file_event	windows	Sysmon	Execution Command and Scripting Interpreter Command and Control Ingress Tool Transfer	-	medium	Micah Babinski	2023-10-15	—	1a433e1d-03d2-47a6-8063-ece992cf4e73
Splunk	The following analytic detects the use of Certify or Certipy tools to enumerate Active Directory Certificate Services (AD CS) environments. (...)	Generic	stable	process_creation	windows	Sysmon · WinEventLog Security · CrowdStrike	Command and Control Ingress Tool Transfer Credential Access Steal or Forge Authentication Certificates	-	medium	Steven Dick	2023-07-28	2026-05-13	e6d2dc61-a8b9-4b03-906c-da0ca75d71b8
	Detects the installation of a Callout DLL via CalloutDlls and CalloutEnabled parameter in Registry, (...)	Generic	test	registry_set	windows	Sysmon · WinEventLog Security	Execution, Stealth Hijack Execution Flow DLL Persistence, Defense Impairment Modify Registry	-	high	Dimitrios Slamaris	2017-05-15	2023-08-17	9d3436ef-9476-4c43-acca-90ce06bdf33a
	This rule detects a DHCP server error in which a specified Callout DLL (in registry) could not be lo (...)	Generic	test	-	windows	WinEventLog System	Execution, Stealth Hijack Execution Flow DLL	-	high	Dimitrios Slamaris, @atc_project (fix)	2017-05-15	2022-12-25	75edd3fd-7146-48e5-9848-3013d7f0282c
	This rule detects a DHCP server in which a specified Callout DLL (in registry) was loaded	Generic	test	-	windows	WinEventLog System	Execution, Stealth Hijack Execution Flow DLL	-	high	Dimitrios Slamaris	2017-05-15	2022-12-25	13fc89a9-971e-4ca6-b9dc-aa53a445bf40
	Detects DLL sideloading activity seen used by Diamond Sleet APT	Emerging	test	image_load	windows	Sysmon	Execution, Stealth Hijack Execution Flow DLL	CVE-2023-42793	high	Nasreddine Bencherchali (Nextron Systems)	2023-10-24	—	d1b65d98-37d7-4ff6-b139-2d87c1af3042
Splunk	The following analytic detects the modification of the registry to disable UAC remote restriction by setting the "LocalAccountTokenFilterPolicy" value to "0x00000001". (...)	Generic	stable	registry_event	windows	Sysmon	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control	-	medium	Teoderick Contreras, Splunk, Steven Dick	2021-09-29	2026-05-13	9928b732-210e-11ec-b65e-acde48001122
Splunk	The following analytic identifies modifications to the registry key that controls the enforcement of Windows User Account Control (UAC). (...)	Generic	stable	registry_event	windows	Sysmon	Privilege Escalation Abuse Elevation Control Mechanism Bypass User Account Control	-	medium	David Dorsey, Patrick Bareiss, Splunk	2020-04-29	2026-10-09	bbc644bc-37df-4e1a-9c88-ec9a53e2038c
	Hunts known SVR-specific DLL names.	Emerging	test	image_load	windows	Sysmon	Execution, Stealth Hijack Execution Flow DLL	-	medium	CISA	2023-12-18	—	e64c8ef3-9f98-40c8-b71e-96110991cb4c
	Detects when an attacker create a similar folder structure to windows system folders such as (Window (...)	Generic	test	file_event	windows	Sysmon	Execution, Stealth Hijack Execution Flow DLL	-	high	frack113, Nasreddine Bencherchali (Nextron Systems)	2022-07-30	—	b6f91281-20aa-446a-b986-38a92813a18f
	Detects execution of VMware Xfer utility (VMwareXferlogs.exe) from the non-default directory which m (...)	Generic	test	process_creation	windows	Sysmon · WinEventLog Security	Execution, Stealth Hijack Execution Flow DLL	-	high	Nasreddine Bencherchali (Nextron Systems)	2022-08-02	—	ebea773c-a8f1-42ad-a856-00cb221966e8

Title

Description