Stuxnet was the first publicly reported piece of malware to specifically target industrial control systems devices. Stuxnet is a large and complex piece of malware that utilized multiple different behaviors including multiple zero-day vulnerabilities, a sophisticated Windows rootkit, and network infection routines.[1][2][3][4] Stuxnet was discovered in 2010, with some components being used as early as November 2008.[1]

ID: S0603
Associated Software: W32.Stuxnet
Platforms: Windows
Version: 1.4
Created: 14 December 2020
Last Modified: 10 April 2024

Associated Software Descriptions

Name Description


Techniques Used

Domain ID Name Use
Enterprise T1134 .001 Access Token Manipulation: Token Impersonation/Theft

Stuxnet attempts to impersonate an anonymous token to enumerate bindings in the service control manager.[1]

Enterprise T1087 .001 Account Discovery: Local Account

Stuxnet enumerates user accounts of the local host.[1]

.002 Account Discovery: Domain Account

Stuxnet enumerates user accounts of the domain.[1]

Enterprise T1071 .001 Application Layer Protocol: Web Protocols

Stuxnet uses HTTP to communicate with a command and control server. [1]

Enterprise T1560 .003 Archive Collected Data: Archive via Custom Method

Stuxnet encrypts exfiltrated data via C2 with static 31-byte long XOR keys.[1]

Enterprise T1543 .003 Create or Modify System Process: Windows Service

Stuxnet uses a driver registered as a boot start service as the main load-point.[1]

Enterprise T1132 .001 Data Encoding: Standard Encoding

Stuxnet transforms encrypted binary data into an ASCII string in order to use it as a URL parameter value.[1]

Enterprise T1140 Deobfuscate/Decode Files or Information

Stuxnet decrypts resources that are loaded into memory and executed.[1]

Enterprise T1573 .001 Encrypted Channel: Symmetric Cryptography

Stuxnet encodes the payload of system information sent to the command and control servers using a one byte 0xFF XOR key. Stuxnet also uses a 31-byte long static byte string to XOR data sent to command and control servers. The servers use a different static key to encrypt replies to the implant.[1]

Enterprise T1480 Execution Guardrails

Stuxnet checks for specific operating systems on 32-bit machines, Registry keys, and dates for vulnerabilities, and will exit execution if the values are not met.[1]

Enterprise T1041 Exfiltration Over C2 Channel

Stuxnet sends compromised victim information via HTTP.[1]

Enterprise T1068 Exploitation for Privilege Escalation

Stuxnet used MS10-073 and an undisclosed Task Scheduler vulnerability to escalate privileges on local Windows machines.[1]

Enterprise T1210 Exploitation of Remote Services

Stuxnet propagates using the MS10-061 Print Spooler and MS08-067 Windows Server Service vulnerabilities.[1]

Enterprise T1008 Fallback Channels

Stuxnet has the ability to generate new C2 domains.[1]

Enterprise T1083 File and Directory Discovery

Stuxnet uses a driver to scan for specific filesystem driver objects.[1]

Enterprise T1562 Impair Defenses

Stuxnet reduces the integrity level of objects to allow write actions.[1]

Enterprise T1070 Indicator Removal

Stuxnet can delete OLE Automation and SQL stored procedures used to store malicious payloads.[1]

.004 File Deletion

Stuxnet uses an RPC server that contains a routine for file deletion and also removes itself from the system through a DLL export by deleting specific files.[1]

.006 Timestomp

Stuxnet extracts and writes driver files that match the times of other legitimate files.[1]

Enterprise T1570 Lateral Tool Transfer

Stuxnet uses an RPC server that contains a file dropping routine and support for payload version updates for P2P communications within a victim network.[1]

Enterprise T1112 Modify Registry

Stuxnet can create registry keys to load driver files.[1]

Enterprise T1106 Native API

Stuxnet uses the SetSecurityDescriptorDacl API to reduce object integrity levels.[1]

Enterprise T1135 Network Share Discovery

Stuxnet enumerates the directories of a network resource.[1]

Enterprise T1027 .013 Obfuscated Files or Information: Encrypted/Encoded File

Stuxnet uses encrypted configuration blocks and writes encrypted files to disk.[1]

Enterprise T1120 Peripheral Device Discovery

Stuxnet enumerates removable drives for infection.[1]

Enterprise T1055 .001 Process Injection: Dynamic-link Library Injection

Stuxnet injects an entire DLL into an existing, newly created, or preselected trusted process.[1]

Enterprise T1090 .001 Proxy: Internal Proxy

Stuxnet installs an RPC server for P2P communications.[1]

Enterprise T1012 Query Registry

Stuxnet searches the Registry for indicators of security programs.[1]

Enterprise T1021 Remote Services

Stuxnet can propagate via peer-to-peer communication and updates using RPC.[1]

.002 SMB/Windows Admin Shares

Stuxnet propagates to available network shares.[1]

Enterprise T1091 Replication Through Removable Media

Stuxnet can propagate via removable media using an autorun.inf file or the CVE-2010-2568 LNK vulnerability.[1]

Enterprise T1014 Rootkit

Stuxnet uses a Windows rootkit to mask its binaries and other relevant files.[1]

Enterprise T1053 .005 Scheduled Task/Job: Scheduled Task

Stuxnet schedules a network job to execute two minutes after host infection.[1]

Enterprise T1505 .001 Server Software Component: SQL Stored Procedures

Stuxnet used xp_cmdshell to store and execute SQL code.[1]

Enterprise T1129 Shared Modules

Stuxnet calls LoadLibrary then executes exports from a DLL.[1]

Enterprise T1518 .001 Software Discovery: Security Software Discovery

Stuxnet enumerates the currently running processes related to a variety of security products.[1]

Enterprise T1553 .002 Subvert Trust Controls: Code Signing

Stuxnet used a digitally signed driver with a compromised Realtek certificate.[1]

Enterprise T1082 System Information Discovery

Stuxnet collects system information including computer and domain names, OS version, and S7P paths.[1]

Enterprise T1016 System Network Configuration Discovery

Stuxnet collects the IP address of a compromised system.[1]

Enterprise T1124 System Time Discovery

Stuxnet collects the time and date of a system when it is infected.[1]

Enterprise T1080 Taint Shared Content

Stuxnet infects remote servers via network shares and by infecting WinCC database views with malicious code.[1]

Enterprise T1078 .001 Valid Accounts: Default Accounts

Stuxnet infected WinCC machines via a hardcoded database server password.[1]

.002 Valid Accounts: Domain Accounts

Stuxnet attempts to access network resources with a domain account’s credentials.[1]

Enterprise T1047 Windows Management Instrumentation

Stuxnet used WMI with an explorer.exe token to execute on a remote share.[1]

ICS T0807 Command-Line Interface

Stuxnet will store and execute SQL code that will extract and execute Stuxnet from the saved CAB file using xp_cmdshell with the following command: set @s = master..xp _ cmdshell extrac32 /y +@t+ +@t+x; exec(@s); [1]

ICS T0885 Commonly Used Port

Stuxnet attempts to contact command and control servers on port 80 to send basic information about the computer it has compromised. [1]

ICS T0866 Exploitation of Remote Services

Stuxnet executes malicious SQL commands in the WinCC database server to propagate to remote systems. The malicious SQL commands include xp_cmdshell, sp_dumpdbilog, and sp_addextendedproc. [1]

ICS T0891 Hardcoded Credentials

Stuxnet uses a hardcoded password in the WinCC software's database server as one of the mechanisms used to propagate to nearby systems. [1]

ICS T0874 Hooking

Stuxnet modifies the Import Address Tables DLLs to hook specific APIs that are used to open project files. [1]

ICS T0877 I/O Image

Stuxnet copies the input area of an I/O image into data blocks with a one second interval between copies, forming a 21 second recording of the input area. The input area contains information being passed to the PLC from a peripheral. For example, the current state of a valve or the temperature of a device. [1]

ICS T0867 Lateral Tool Transfer

Stuxnet sends an SQL statement that creates a table and inserts a binary value into the table. The binary value is a hex string representation of the main Stuxnet DLL as an executable file (formed using resource 210) and an updated configuration data block. [1]

ICS T0835 Manipulate I/O Image

When the peripheral output is written to, sequence C intercepts the output and ensures it is not written to the process image output. The output is the instructions the PLC sends to a device to change its operating behavior. By intercepting the peripheral output, Stuxnet prevents an operator from noticing unauthorized commands sent to the peripheral. [1]

ICS T0831 Manipulation of Control

Stuxnet can reprogram a PLC and change critical parameters in such a way that legitimate commands can be overridden or intercepted. In addition, Stuxnet can apply inappropriate command sequences or parameters to cause damage to property. [1]

ICS T0832 Manipulation of View

Stuxnet manipulates the view of operators replaying process input and manipulating the I/O image to evade detection and inhibit protection functions. [4] [1]

ICS T0849 Masquerading

Stuxnet renames s7otbxdx.dll, a dll responsible for handling communications with a PLC. It replaces this dll file with its own version that allows it to intercept any calls that are made to access the PLC. [1]

ICS T0821 Modify Controller Tasking

Stuxnet infects OB1 so that its malicious code sequence is executed at the start of a cycle. It also infects OB35. OB35 acts as a watchdog, and on certain conditions, it can stop the execution of OB1. [1]

ICS T0836 Modify Parameter

In states 3 and 4 Stuxnet sends two network bursts (done through the DP_SEND primitive). The data in the frames are instructions for the frequency converter drives. For example one of the frames contains records that change the maximum frequency (the speed at which the motor will operate). The frequency converter drives consist of parameters, which can be remotely configured via Profibus. One can write new values to these parameters changing the behavior of the device. [1]

ICS T0889 Modify Program

Stuxnet infects PLCs with different code depending on the characteristics of the target system. An infection sequence consists of code blocks and data blocks that will be downloaded to the PLC to alter its behavior. [1]

ICS T0801 Monitor Process State

Stuxnet examines fields recorded by the DP_RECV monitor to determine if the target system is in a particular state of operation. [1]

ICS T0834 Native API

Stuxnet calls system function blocks which are part of the operating system running on the PLC. Theyre used to execute system tasks, such as reading the system clock (SFC1) and generating data blocks on the fly. [1]

ICS T0842 Network Sniffing

DP_RECV is the name of a standard function block used by network coprocessors. It is used to receive network frames on the Profibus a standard industrial network bus used for distributed I/O. The original block is copied to FC1869, and then replaced by a malicious block. Each time the function is used to receive a packet, the malicious Stuxnet block takes control: it will call the original DP_RECV in FC1869 and then perform postprocessing on the packet data. The replaced DP_RECV block (later on referred to as the DP_RECV monitor) is meant to monitor data sent by the frequency converter drives to the 315-2 CPU via CP 342-5 Profibus communication modules. [1]

ICS T0843 Program Download

Stuxnet's infection sequence consists of code blocks and data blocks that will be downloaded to the PLC to alter its behavior. [1]

ICS T0873 Project File Infection

Stuxnet copies itself into Step 7 projects in such a way that it automatically executes when the Step 7 project is loaded. [1]

ICS T0886 Remote Services

Stuxnet executes malicious SQL commands in the WinCC database server to propagate to remote systems. The malicious SQL commands include xp_cmdshell, sp_dumpdbilog, and sp_addextendedproc. [1]

ICS T0888 Remote System Information Discovery

Stuxnet enumerates and parses the System Data Blocks (SDB) using the s7blk_findfirst and s7blk_findnext API calls in s7otbxdx.dll. Stuxnet must find an SDB with the DWORD at offset 50h equal to 0100CB2Ch. This specifies that the system uses the Profibus communications processor module CP 342-5. In addition, specific values are searched for and counted: 7050h and 9500h. 7050h is assigned to part number KFC750V3 which appears to be a frequency converter drive (also known as variable frequency drive) manufactured by Fararo Paya in Teheran, Iran. 9500h is assigned to Vacon NX frequency converter drives manufactured by Vacon based in Finland.[1]

Stuxnet was specifically targeting CPUs 6ES7-315-2 (Series 300) with special system data block characteristics for sequence A or B and 6ES7-315-2 for sequence C. The PLC type can also be checked using the s7ag_read_szl API.[1]

ICS T0847 Replication Through Removable Media

Stuxnet was able to self-replicate by being spread through removable drives. A willing insider or unknown third party, such as a contractor, may have brought the removable media into the target environment. [1] The earliest version of Stuxnet relied on physical installation, infecting target systems when an infected configuration file carried by a USB stick was opened. [4]

ICS T0851 Rootkit

One of Stuxnet's rootkits is contained entirely in the fake s7otbxdx.dll. In order to continue existing undetected on the PLC it needs to account for at least the following situations: read requests for its own malicious code blocks, read requests for infected blocks (OB1, OB35, DP_RECV), and write requests that could overwrite Stuxnets own code. Stuxnet contains code to monitor and intercept these types of requests. The rootkit modifies these requests so that Stuxnets PLC code is not discovered or damaged. [4]

ICS T0869 Standard Application Layer Protocol

Stuxnet uses a thread to monitor a data block DB890 of sequence A or B. This thread is constantly running and probing this block (every 5 minutes). On an infected PLC, if block DB890 is found and contains a special magic value (used by Stuxnet to identify his own block DB890), this blocks data can be read and written. This thread is likely used to optimize the way sequences A and B work, and modify their behavior when the Step7 editor is opened. [1]

ICS T0863 User Execution

Stuxnet infects DLL's associated with the WinCC Simatic manager which are responsible for opening project files. If a user opens an uninfected project file using a compromised manager, the file will be infected with Stuxnet code. If an infected project is opened with the Simatic manager, the modified data file will trigger a search for the xyz.dll file. If the xyz.dll file is not found in any of the specified locations, the malicious DLL will be loaded and executed by the manager. [1]