Announcing AttackIQ’s Malware Emulation Attack Graphs

We are immensely pleased to announce the first of AttackIQ’s “malware emulation attack graphs.” We broke down real-world malware into its logical steps to understand the adversary’s behavior. We then use our attack graph methodology to arrange the malware into its component tactics, techniques, and procedures. Using the malware emulation attack graph, defenders can emulate a specific strain of malware to test and validate their security controls. Take a look. Read More

Malware often forms the foundation for an adversary cyberattack, giving adversaries a means to employ a range of tactics, techniques, and procedures (TTPs) against a target to achieve their strategic objectives. For analysts, adversary malware also provides insights into an adversary’s behavior when more complete incident response data is unavailable, particularly at the procedure level. Defenders can then improve their security posture by testing their defenses against the malware in advance. But only if the assessment can be done easily.

Attack graphs give us a means of arranging real-world malware into its component TTPs to run emulations, and today we are immensely excited to announce our new malware emulation attack graphs.

How do we build it? AttackIQ’s adversary research team analyzes real-world malware and then arranges the TTPs into a logical flow that emulates specific adversary behaviors. The resulting attack graph gives you a cornerstone of hard data – a detailed adversary emulation – to run against your security program and test your defense performance.

What sets malware emulation attack graphs apart from AttackIQ’s other attack graphs is their focus on the TTPs made possible by the malware itself (rather than in an entire adversary intrusion sequence, which could include manual TTPs). Often in incident reports, malware TTPs are either unknown or not understood. Analysts often don’t know whether the TTPs reported in an incident are features of the malware itself, or if they are employed by an intruder manually. AttackIQ’s malware emulation attack graphs focus on key aspects of malware used across many campaigns. They give defenders the opportunity to validate and tune their endpoint security controls and network security controls against each logical stage of a specific malware strain.

Specifically, a malware-based threat assessment helps defensive teams to:

  • identify core behavior observed in specific malware samples
  • identify the security technologies that can detect and prevent behaviors in specific malware samples
  • evaluate the efficacy of defensive technologies (and the overarching security stack) in detecting and preventing specific malware behaviors; and
  • identify gaps in the team’s security posture that could be filled or improved to detect and prevent specific TTPs.

To kick off these new attack graphs, we chose the ever-prevalent Sogu (a.k.a. PlugX) remote access tool (RAT) and the recent Rust-based ransomware, BlackCat (a.k.a. ALPHV). We will cover these new additions to the AttackIQ Security Optimization Platform in a live demo on May 26, 2022 at 10.000 hrs PT.

Sogu (PlugX)

Sogu (a.k.a. PlugX) is a full-featured, modular RAT with many variants and is used by multiple China-based groups within the espionage threat class, to include APT41, APT10, UNC124, Mustang Panda, and others. Sogu has been around for more than a decade with early reporting as far back as 2008, yet it continues to target victims around the world, to include the semiconductor industry and nation-state governments.

Our Sogu/PlugX attack graph is derived from a sample used in an intrusion by China-based threat actors that targeted the semiconductor and high-tech subsector of the manufacturing industry in July 2020.

This sample was delivered in a self-extracting (SFX) RAR file which contains three files required to implement a DLL side-loading method of execution. When this SFX RAR file is opened by an unwitting user, these files are written to disk and the executable is run.

  1. Legitimate kick-off executable (in the sample analyzed this was a McAfee program).
  2. Hijacked DLL that loads/launches Sogu/PlugX (this DLL is considered hijacked because the legitimate program will natively load the DLL).
  3. Encrypted file holding encrypted Sogu shellcode payload.

This method and required set of files is commonly seen with Sogu/PlugX variants.

Metadata from the sample analyzed

Description: SFX RAR file
Size (bytes): 327583
SHA1: 09deeb57240711b9fcf33d0b154c9ffd0e0984b1

Description: Legitimate exe file
Size (bytes): 140576
SHA1: d201b130232e0ea411daa23c1ba2892fe6468712

Description: Hijacked DLL, loads the payload file
Size (bytes): 199168
SHA1: 040ae092a0ab8801a92c4d0d533a03ce13595e1f

Description: Encrypted payload file
Size (bytes): 121128
SHA1: eb9f611889ef99c7b0c4006e1dea50dd5a8c7f93

This attack graph focuses on the sample’s core TTPs, captured by the following scenarios that emulate behavior as the malware progresses through its code execution.

Attack Graph SoguClick for Larger View

Scenarios 1 and 2: Initial Access: Spearphishing (T1566.002): Sogu is commonly delivered to targets using spearphishing links. For the first scenario in the graph, we begin with the step after a link was clicked by downloading the SFX RAR file package to the endpoint, giving A/V and potentially network security controls the opportunity to detect and or prevent delivery.

1a. Detection Process

Parent Process Name == (Winword.exe OR Excel.exe OR Powerpnt.exe)
Process Name == (cmd.exe OR powershell.exe)
Command Line CONTAINS ((“DownloadString OR DownloadFile) AND HTTP AND (Invoke-Expression OR IEX)

1b. Mitigation Policies

MITRE recommends the following mitigations for T1566.002:

Scenario 3: Save Malicious DLL to Disk: If the SFX RAR file is successfully opened, the trio of files will be written to the victim’s disk. Of these three files, the malicious DLL gives another opportunity to test A/V protection since it isn’t obfuscated like the encrypted Sogu shellcode payload file. This scenario saves the constituent hijacked DLL to disk, mimicking the SFX RAR file’s write operation to the host machine.

3a. Detection Process

While A/V, NGAV and EPP security controls excel at detecting malicious files being saved to disk, Application Control technologies provide opportunities to detect unsigned DLLs being saved to disk. Further, execution of unsigned filetypes (such as DLLs) specified in your Application Control policies can prevented/blocked. Additionally, EDR technologies have the ability to detect these unsigned filetypes being saved to globally writable directories on devices. However, the latter may be false positive prone and lead to excessive alerts. In addition to looking for unsigned DLLs being placed in globally writable directories, using YARA detections to look for strings in malware files is an alternate/effective way of detecting this activity on your endpoints:

3b. Mitigation Policies

  • Ensure that devices are placed within a protective (not detective) antivirus policy to act on files through static and dynamic analysis.
  • Ensure account management is correctly configured through group policy, ensuring proper users only have rights to write to sensitive areas on disk.
  • Ensure application control technology policies are thought-through, tuned and maintained; you can get very granular with what types of files are indexed and can execute on which systems in your network. For example, self-extracting RAR files can be banned entirely on your network, or unsigned DLLs can be prevented from executing. Attempted execution of banned files is logged and can flow into your SIEM for further alerting or correlation.

Scenario 4: Hijack Execution Flow: DLL Side-Loading (T1574.002): Once the three files are written to disk, the SFX RAR file automatically runs the legitimate McAfee executable leading to DLL side-loading technique. In DLL side-loading, the legitimate binary attempts to load a required DLL and instead of loading the normal benign DLL, a hijacked version is loaded because it resides in the same directory as the McAfee executable.

4a. Detection Process

Process Name == evt.exe (This is the name of the trusted McAfee executable extracted from the RAR file. This binary name is subject to change)
Imageload Name == McUtil.dll (This is the name of the DLL) extracted from the RAR file. This binary name is subject to change
Imageload is_signed == False

4b. Mitigation Policies

MITRE recommends the following mitigations for T1574.002:

Additionally, if the legitimate file that is used to load a DLL is not a binary needed for your organization, add the hashes to your application control block lists as soon as possible. Binaries on a block list will not be able to execute even if they are benign by nature.

Scenario 5: Process Injection (T1055.001): Sogu uses process injection both reflectively and remotely to evade defenses. Malicious code can sometimes go undetected by security products because it is running inside a legitimate process. Our emulation mimics DLL code injection by using Windows API calls to LoadLibrary and CreateRemoteThread to inject code into a legitimate process.

5a. Detection Process

  • Utilize tools such as Procmon.exe or EDR tools to monitor for system Windows API calls such as “LoadLibrary” and “CreateRemoteThread” with unsigned or unrecognized binaries, especially if they are coming from locations that are globally writable or not belonging to the associated injected process.

Process Name == evt.exe (This is the name of the trusted McAfee executable extracted from the RAR file. This binary name is subject to change)
Imageload Name == McUtil.dll (This is the name of the .dll extracted from the RAR file. This binary name is subject to change)
Imageload is_signed == False

5b. Mitigation Policies

MITRE recommends the following mitigations for T1055.001:

Scenario 6: Persistence via Windows Service (T1543.003): If the malware executes with elevated privilege, persistence is established by creating a new service that will initiate the execution of the benign McAfee binary, starting the process of malicious code execution again.

6a. Detection Process

Process Name == (cmd.exe or powershell.exe)
Command Line CONTAINS ((‘sc’ or ‘sc.exe’) AND ‘create’ AND ‘binpath=”<path to trusted executable>”’ AND start=”auto”)

6b. Mitigation Policies

MITRE recommends the following mitigations for T1543.003:

Scenario 7: Persistence via Registry Run Key (T1547.001): Alternatively, if the malware is executed as a normal user, persistence is achieved using a standard registry run key. Our attack graph will take this persistence path if the service creation is prevented in the previous scenario.

7a. Detection Process

As registry key modifications is typical for Windows system behavior, it is unusual if you observe registry actions attempted to be carried out by unexpected or underprivileged users. This detection will exclude administrative or expected users to reduce false positives from expected system usage.

Process Name == (cmd.exe or powershell.exe)

User NOT IN <list of expected reg.exe users>

Command Line CONTAINS((reg or reg.exe) AND (“HKEY_CURRENT_USER” OR “KEY_CURRENT_MACHINE”) AND “\SOFTWARE\Microsoft\Windows\CurrentVersion\” AND (“run” OR “runonce”))

7b. Mitigation Policies

Although it is expected Windows behavior for this registry key to be modified for programs to start at boot, modification to these registry keys can be constrained by setting group policy and application control/whitelisting but allowing only authorized users to utilize tools such as cmd.exe, powershell.exe, reg.exe, and regedit.exe

Scenario 8 and 9: Command and Control: DNS (T1071.004): After persistence is set, the malware establishes communication with command and control (C2) infrastructure by abusing the Domain Name System (DNS) application layer protocol to avoid detection/network filtering.

This Sogu sample is configured to send DNS callouts in TXT records that carry encoded victim information prepended to the threat actor-controlled domain. Example:

An initial DNS request is sent through a hardcoded public Google DNS server,, which we assess to be a way around potential internal network DNS blacklisting implemented by the victim organization’s security team.

If the Google DNS resolution fails, potentially due to web proxy or DNS policy disallowing external DNS requests, a fallback callout that is identical in content is sent to the host’s default DNS server. Our scenario emulates the structure of the encoded data in these callouts and is sent to AttackIQ infrastructure. This provides defenders the opportunity to build network detections for anomalous DNS traffic like this, which could prove useful beyond Sogu detection.

8a. Detection Process

Typically, C2 traffic is sent through HTTP/HTTPS which is often monitored by network firewalls and content filtering security controls. Threat actors using Sogu/PlugX utilize the DNS protocol to remain undetected. Creating network Snort rules to alert on any UDP 53 connections to flagged IPs may be an effective way to alert on possible C2 activity from threat actors utilizing this technique.

alert udp any 53 -> $HOME_NET any (msg:"*"; rev:001; content:"|43 D7 41 85|";)

  • Please note, the content portion here is a hash representation of the destination IP address for the DNS request (i.e., to the C2). This portion should be modified as IP artifacts are collected.

8b. Mitigation Policies

MITRE recommends the following mitigations for T1071.004:

Scenario 10: Input Capture: Keylogging (T1056.001): With the C2 channel established, the running implant can now receive commands or Sogu plugins enabling additional capability from the external C2 server. One of the most common commands received is the enabling of keylogging functionality. The scenario uses a system hooking routine to capture any keystrokes using calls to the Windows API.

10a. Detection Process

MITRE detection recommendations for T1056.001:

Scenario 11: Windows Command Shell (T1059.003): Another post-exploitation behavior of Sogu is the use of the Windows command shell for execution of reconnaissance commands. If the keylogger activity in the previous scenario is prevented by security controls, a command shell is initiated and the following commands are executed: ipconfig, whoami, systeminfo

11a. Detection Process

Process Name == (cmd.exe OR powershell.exe)
Command Line CONTAINS “systeminfo”
User NOT IN User != [<list of expected administrators to be issuing these commands>]

11b. Mitigation Policies

MITRE mitigation Recommendations for T1059.003:

Additionally, ensure that Group Policy is set and enforced to allow only authorized users/administrators to be able to run cmd.exe or powershell.exe. These interpreters can be limited to lower privileged or unneeded users to prevent enumeration or abuse.

Scenario 12: Data Exfiltration Over HTTP (T1048.003): In our final technique of the attack graph, we emulate exfiltration of data over HTTP by compressing mocked data and transmitting to an AttackIQ controlled server.

12a. Detection Process

MITRE detection Recommendations for T1048.003:

12b. Mitigation Policies

MITRE mitigation Recommendations for T1048.003:

BlackCat (ALPHV) Ransomware

BlackCat (a.k.a ALPHV) emerged as ransomware-as-a-Service (RaaS) as early as mid-November 2021, providing would-be attackers with a highly configurable multi-platform ransomware strain written in Rust. BlackCat operators use the double-threat extortion model which not only encrypts victim data but also threatens public exposure of sensitive information that was collected and exfiltrated prior to ransomware deployment.

According to an April 2022 FBI report, BlackCat has compromised at least 60 organizations worldwide through March 2022. True to the nature of RaaS, victim sectors are wide ranging, and have been reported to include German oil, European port authorities, high-end fashion/apparel, and higher education institutions in the United States.

The sample analyzed for our content development was obtained from a known public malware repository and was first submitted to VirusTotal in December 2021.

Sample Metadata

Description: BlackCat.exe (Win32)
Size (bytes): 327583
SHA1: 09deeb57240711b9fcf33d0b154c9ffd0e0984b1

Our BlackCat attack graph emulates a series of core behaviors beginning with introducing the ransomware to the environment, moving through configuration of the host for efficient and effective encryption, preparation for propagation, and finally to BlackCat’s ransomware encryption method.

Attack Graph BlackCatClick for Larger View

Scenarios 1 and 2: Ingress Tool Transfer (T1105): Intruders bring BlackCat into a victim environment after it has been breached. To begin this attack graph, we assume that initial access has been achieved and we emulate the introduction of the ransomware to the endpoint. This pair of scenarios downloads and saves a Windows-based BlackCat sample to disk, giving A/V security controls an opportunity to detect inbound tool delivery, as well as uploads to memory.

1a. Detection Process

Once a malicious actor has compromised an endpoint, they may attempt to transfer any tools or malware onto the device. Attackers may utilize tools such as PowerShell, Certutil, Bitsadmin, and Curl.

PowerShell Example:

Process Name == (Cmd.exe OR Powershell.exe)
Command Line CONTAINS((“IWR” OR “Invoke-WebRequest") AND “DownloadData” AND “Hidden”)

Certutil Example:

Process Name == Certutil.exe
Command Line Contains (“-urlcache” AND “-f”)

Bitsadmin Example:

Process Name == Bitsadmin.exe
Command Line CONTAINS (“/transfer” AND “http”)

Curl Example:

Process Name == Curl.exe
Command Line CONTAINS (“http” AND “-o”)

1b. Mitigation Policies

MITRE mitigation Recommendations for T1105:

Additionally, it is advised that non administrators be prevented from using tools such as powershell.exe, cmd.exe, and certutil.exe. This will prevent malicious usage of these tools on end user accounts.

Scenario 3: Windows Management Instrumentation (WMI) Commands (T1047): One of the first things BlackCat does is grab the host machine’s Windows UUID which is used to build a unique victim identifier for the ransom process. The malware retrieves this piece of information by using a living-off-the-land tool, WMI, to issue the following command “csproduct get UUID”.

3a. Detection Process

Developing a baseline of typical binaries that wmiprvse.exe invokes in your environment, then utilizing that baseline to make a detection is a good step in monitoring abnormal Windows Management Instrumentation activity. For example, creating a detection to alert on processes not in a list of known processes being invoked from wmiprvse.exe would identify possible malicious activity.

Monitoring the endpoint for the following would also alert on possible suspicious use:

Process Name == wmic.exe
Command Line CONTAINS (“Process call create” AND(“.dll” OR “.exe”))

3b. Mitigation Policies

MITRE mitigation Recommendations for T1047:

Additionally, ensure only administrators are authorized to utilize the Windows Management Instrumentation as this tool may be utilized for enumeration, lateral movement, and command execution as seen in this scenario.

Scenario 4: Impair Defenses: Disable or Modify Tools (T1562.001): Here, we implement a new custom scenario that emulates BlackCat’s attempt to allow Remote Symbolic Links on the host using the fsutil command. Enabling these remote symbolic links can expand access to remote file locations for encryption as well as create additional pathways for propagation.

4a. Detection Process

Process Name == (cmd.exe or powershell.exe)
Command Line CONTAINS (“fsutil” AND “SymlinkEvaluation” AND (“R2L:1” OR “R2R:1”))

4b. Mitigation Policies

MITRE mitigation Recommendations for T1562.001:

Scenario 5: Modify Registry (T1112): In this scenario we emulate BlackCat’s addition of a registry key that maximizes concurrent network requests made by the host, likely to prevent any hiccups during file encryption of remotely available files. The “MaxMpxCt” key is set to 65535.

5a. Detection Process

Process Name == (cmd.exe or powershell.exe)
Command Line CONTAINS ((“reg” OR “reg.exe”) AND “add” AND “HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters” AND “/V MaxMpxCt”)

5b. Mitigation Policies

MITRE mitigation Recommendations for T1112:

Scenario 6: File Deletion: Volume Shadow Copy (T1070.004): Using the Windows command shell, this scenario reproduces the deletion of Volume Shadow Copies. BlackCat and other ransomware lines make use of this technique to restrict the victim’s ability to restore the encrypted files from backup.

6a. Detection Process

Process Name == vssadmin.exe
Command Line CONTAINS ("delete shadows“)

6b. Mitigation Policies

It is recommended that group policy settings and Application Control/whitelisting software is set to only allow authorized users access to tools such as vssadmin.exe, cmd.exe, and powershell.exe to prevent misusage if an account is compromised.

Additionally, ensure that backup files are set to only be accessed by authorized personnel. These backup files should not have read or write access to underprivileged user accounts.

Scenario 7: System Network Configuration Discovery (T1016): If configured, BlackCat will propagate on a victim’s local network. In order to spread itself to neighbor machines, discovery actions are needed to identify pathways available from the origin host. Network topology data points are obtained with a copy of BlackCat’s network share discovery and MAC address snooping with “arp” commands.

7a. Detection Process

Typically, system enumeration is carried out by using benign, Windows applications. This allows an attacker to gain additional information about the target environment without setting off alarms by using malware or possibly AV flagged software. Since these techniques are utilized by benign Windows processes, the following detections should be taken into account with expected users like network administrators to reduce false positives:

Enumeration through “net” command

Process Name == (cmd.exe or powershell.exe)
Command Line CONTAINS (("net“ OR “net.exe”) AND “use”)
User NOT IN <list of expected net.exe users>

Enumeration through “arp” command

Process Name == (cmd.exe or powershell.exe)
Command Line CONTAINS (arp -a)
User NOT IN <list of expected network admins>

7b. Mitigation Policies

Although these are benign Windows commands, they can be used maliciously if threat actors have an account compromised. To reduce this information disclosure, cmd.exe and powershell.exe should be excluded to only necessary administrative users.

Additionally, Windows command line Audit Process Creation auditing can be enabled to see event ID 4688. Enable the GPO setting to “include command line in process creation events.” Windows CLI events can be filtered and forwarded to a SIEM from all endpoints for further filtering, tuning and correlation for detection of anomalous activity.

Scenario 8: Ingress Tool Transfer (T1105): BlackCat carries a copy of the PsExec utility in its resources that is written to disk and likely used to spread itself if configured for propagation. In the sample we analyzed propagation is not enabled, however we included this behavior because it is a configurable option and a tool commonly abused by attackers to achieve various results including moving files over the network and remote process execution.

8a. Detection Process

PsExec is not malicious by nature and is signed by Microsoft as it is a Microsoft published SysInternals tool. This tool may be used maliciously to move laterally on devices within a network, and should be monitored for authorized usage only. If this is not an expected binary in your environment for network administrators to utilize, then we recommend monitoring for this file periodically to see if any have been placed on the system without approved intent. PsExec with alternate credentials specified on the command line is a Logon Type 3+2 event and it should be noted that this passes those credentials in plaintext across the network as well as leaves those credentials vulnerable to theft on the target host. PsExec usage without explicit credentials is a Type 3 Logon event and does not leave any credentials on the target host.

8b. Mitigation Policies

MITRE mitigation Recommendations for T1105:

Even legitimate usage of PsExec is still problematic from a security perspective. For the best security, PsExec should be globally banned from execution using Application Control/whitelisting software. Sys Admin or authorized usage of PowerShell Remoting is a much more secure and preferred option for legitimate Type 3 Logons in your environment and does not leave credentials on the target host.

Scenario 9: File and Directory Discovery (T1083): At this stage of the kill chain, BlackCat preps for file encryption by enumerating the filesystem searching for data to encrypt.

9a. Detection Process

Searching the file system on Windows machines is typically done through the CLI with the use of the “dir” command. This is typical Windows behavior, but monitoring for this behavior may help identify malicious actions in your environment. Often enumerated behavior on endpoints is sent to a file for exfiltration and examination by the attacker:

Process Name == (cmd.exe or powershell.exe)
Command Line CONTAINS (("dir“ AND “>”)

  • Please note, this detection can be very loud if end users or administrators commonly search the file system and save results with the “>” argument. To narrow this detection down, add in sensitive file paths that are not often viewed by typical end users to increase fidelity.

9b. Mitigation Policies

Although these are benign Windows commands, they can be used maliciously if threat actors have an account compromised. To reduce this information disclosure, cmd.exe and powershell.exe should be excluded to only necessary administrative users.

Additionally, ensure that files and directories have proper permissions assigned to prevent unauthorized viewing or modification by underprivileged users.

Scenario 10: Data Encrypted for Impact (T1486): In our last step of the attack graph, we mimic BlackCat’s encryption method implementing 128-bit AES-NI in CTR mode if supported by the host hardware and falling back to ChaCha20 if not. In addition to the specific encryption algorithm, we also emulate parts of the unique encryption process used by BlackCat.

One of these steps is the use of a temporary checkpoint file written to disk, that serves as a position marker if file encryption is interrupted. A checkpoint file is written to disk for each file during the encryption process and then removed once the file has been fully encrypted. The name of this file is the name of the file being encrypted with the string “checkpoints-” prepended to it. This is a unique IOC and could be used in a detection signature.

Another nuance we’ve captured in the encryption scenario is BlackCat’s file extension exclusion list. The configuration block of BlackCat specifies file names, directories, and extensions to exclude from encryption, ensuring the host remains stable during the process and reducing the number of files to encrypt if they provide no ransom value.

We’ve also taken care to emulate the structure of the file after encryption including an encrypted block of JSON that contains the private key and other metadata required to decrypt the file.

10a. Detection Process

A detection rule could be written to catch the checkpoint file written to disk during the encryption process:

FileName starts_with “checkpoints-”

In addition, Blackcat Ransomware group searches for the following extensions to encrypt:

.themepack, .nls, .diagpkg, .msi, .lnk, .exe, .cab, .scr, .bat, .drv, .rtp, .msp, .prf, .msc, .ico, .key, .ocx, .diagcab, .diagcfg, .pdb, .wpx, .hlp, .icns, .rom, .dll, .msstyles, .mod, .ps1, .ics, .hta, .bin, .cmd, .ani, .386, .lock, .cur, .idx, .sys, .com, .deskthemepack, .shs, .ldf, .theme, .mpa, .nomedia, .spl, .cpl, .adv, .icl, .msu

Excessive file modifications to a variety of these file extensions within a very short time window would be an indicator of this impact activity occurring in your environment.

10b. Mitigation Policies

MITRE mitigation Recommendations for T1486:

In summary, AttackIQ’s new malware emulation attack graphs emulate core techniques and procedures designed into the malware as a crucial part of an adversary’s overall kill chain. With data generated from continuous testing and use of this attack graph, you can focus your teams on achieving key security outcomes, adjusting your security controls, and working to elevate your total security program effectiveness against a known and dangerous threat.

AttackIQ stands at the ready to help security teams implement this attack graph and other aspects of the AttackIQ Security Optimization Platform, including through our co-managed security service, AttackIQ Vanguard.