Adversaries may use an existing, legitimate external Web service as a means for relaying data to/from a compromised system. Popular websites, cloud services, and social media acting as a mechanism for C2 may give a significant amount of cover due to the likelihood that hosts within a network are already communicating with them prior to a compromise. Using common services, such as those offered by Google, Microsoft, or Twitter, makes it easier for adversaries to hide in expected noise.[1] Web service providers commonly use SSL/TLS encryption, giving adversaries an added level of protection.
Use of Web services may also protect back-end C2 infrastructure from discovery through malware binary analysis while also enabling operational resiliency (since this infrastructure may be dynamically changed).
| ID | Name | Description |
|---|---|---|
| G0050 | APT32 |
APT32 has used Dropbox, Amazon S3, and Google Drive to host malicious downloads.[2] |
| C0040 | APT41 DUST |
APT41 DUST used compromised Google Workspace accounts for command and control.[3] |
| G1044 | APT42 |
APT42 has used various links, such as links with typo-squatted domains, links to Dropbox files and links to fake Google sites, in spearphishing operations.[4][5][6] |
| S1081 | BADHATCH |
BADHATCH can be utilized to abuse |
| S0534 | Bazar | |
| S0635 | BoomBox |
BoomBox can download files from Dropbox using a hardcoded access token.[10] |
| S1063 | Brute Ratel C4 |
Brute Ratel C4 can use legitimate websites for external C2 channels including Slack, Discord, and MS Teams.[11] |
| S1039 | Bumblebee |
Bumblebee has been downloaded to victim's machines from OneDrive.[12] |
| C0017 | C0017 |
During C0017, APT41 used the Cloudflare services for C2 communications.[13] |
| C0027 | C0027 |
During C0027, Scattered Spider downloaded tools from sites including file.io, GitHub, and paste.ee.[14] |
| S0335 | Carbon | |
| S0674 | CharmPower |
CharmPower can download additional modules from actor-controlled Amazon S3 buckets.[16] |
| S1149 | CHIMNEYSWEEP |
CHIMNEYSWEEP has the ability to use use Telegram channels to return a list of commands to be executed, to download additional payloads, or to create a reverse shell.[17] |
| S1066 | DarkTortilla |
DarkTortilla can retrieve its primary payload from public sites such as Pastebin and Textbin.[18] |
| S0600 | Doki |
Doki has used the dogechain.info API to generate a C2 address.[19] |
| S0547 | DropBook |
DropBook can communicate with its operators by exploiting the Simplenote, DropBox, and the social media platform, Facebook, where it can create fake accounts to control the backdoor and receive instructions.[20][21] |
| G1011 | EXOTIC LILY |
EXOTIC LILY has used file-sharing services including WeTransfer, TransferNow, and OneDrive to deliver payloads.[22] |
| G0037 | FIN6 |
FIN6 has used Pastebin and Google Storage to host content for their operations.[23] |
| G0061 | FIN8 |
FIN8 has used |
| G0117 | Fox Kitten |
Fox Kitten has used Amazon Web Services to host C2.[25] |
| G0047 | Gamaredon Group |
Gamaredon Group has used GitHub repositories for downloaders which will be obtained by the group's .NET executable on the compromised system.[26] |
| S0561 | GuLoader |
GuLoader has the ability to download malware from Google Drive.[27] |
| S0601 | Hildegard | |
| G0100 | Inception |
Inception has incorporated at least five different cloud service providers into their C2 infrastructure including CloudMe.[29][30] |
| S1160 | Latrodectus |
Latrodectus has used Google Firebase to download malicious installation scripts.[31] |
| G0140 | LazyScripter |
LazyScripter has used GitHub to host its payloads to operate spam campaigns.[32] |
| S1221 | MOPSLED |
MOPSLED can use third-party web services such as GitHub and Google Drive for C2.[33] |
| G0129 | Mustang Panda |
Mustang Panda has used DropBox URLs to deliver variants of PlugX.[34] Mustang Panda has also used Google Drive to host malicious downloads.[35] |
| S0198 | NETWIRE |
NETWIRE has used web services including Paste.ee to host payloads.[36] |
| S0508 | ngrok |
ngrok has been used by threat actors to proxy C2 connections to ngrok service subdomains.[37] |
| S1147 | Nightdoor |
Nightdoor can utilize Microsoft OneDrive or Google Drive for command and control purposes.[38][39] |
| C0005 | Operation Spalax |
During Operation Spalax, the threat actors used OneDrive and MediaFire to host payloads.[40] |
| S1130 | Raspberry Robin |
Raspberry Robin second stage payloads can be hosted as RAR files, containing a malicious EXE and DLL, on Discord servers.[41] |
| G1039 | RedCurl |
RedCurl has used web services to download malicious files.[42][43] |
| S1240 | RedLine Stealer |
RedLine Stealer has leveraged legitimate file sharing web services to host malicious payloads.[44][45] |
| G0106 | Rocke |
Rocke has used Pastebin, Gitee, and GitLab for Command and Control.[46][47] |
| S0546 | SharpStage |
SharpStage has used a legitimate web service for evading detection.[20] |
| S1178 | ShrinkLocker |
ShrinkLocker uses a subdomain on the legitimate Cloudflare resource "trycloudflare[.]com" to obfuscate the threat actor's actual address and to tunnel information sent from victim systems.[48] |
| S0589 | Sibot |
Sibot has used a legitimate compromised website to download DLLs to the victim's machine.[49] |
| S0649 | SMOKEDHAM |
SMOKEDHAM has used Google Drive and Dropbox to host files downloaded by victims via malicious links.[50] |
| S1086 | Snip3 |
Snip3 can download additional payloads from web services including Pastebin and top4top.[51] |
| S1124 | SocGholish |
SocGholish has used Amazon Web Services to host second-stage servers.[52] |
| G0139 | TeamTNT |
TeamTNT has leveraged iplogger.org to send collected data back to C2.[53][54] |
| G0010 | Turla |
Turla has used legitimate web services including Pastebin, Dropbox, and GitHub for C2 communications.[15][55] |
| S0689 | WhisperGate |
WhisperGate can download additional payloads hosted on a Discord channel.[56][57][58][59][60] |
| ID | Mitigation | Description |
|---|---|---|
| M1031 | Network Intrusion Prevention |
Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level. |
| M1021 | Restrict Web-Based Content |
Web proxies can be used to enforce external network communication policy that prevents use of unauthorized external services. |
| ID | Name | Analytic ID | Analytic Description |
|---|---|---|---|
| DET0425 | Suspicious Use of Web Services for C2 | AN1189 |
Detects unusual outbound connections to web services from uncommon processes using SSL/TLS, particularly those exhibiting high outbound data volume or persistence. |
| AN1190 |
Detects command-line tools, agents, or scripts making outbound HTTPS connections to popular web services like Discord, Slack, Dropbox, or Graph API in an unusual context. |
||
| AN1191 |
Detects user agents or background services making unauthorized or unscheduled web API calls to cloud/web services over HTTPS. |
||
| AN1192 |
Detects guest VMs or management agents issuing HTTP(S) traffic to external services without a valid patch management or backup justification. |