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TLP:WHITE

Malware Analysis Report (AR18-337B)

MAR-10166283.r1.v1 – SamSam2

Original release date: December 03, 2018

Notification

This report is provided "as is" for informational purposes only. The Department of Homeland Security (DHS) does not provide any warranties of any kind regarding any information contained within. The DHS does not endorse any commercial product or service, referenced in this bulletin or otherwise.

This document is marked TLP:WHITE. Disclosure is not limited. Sources may use TLP:WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction. For more information on the Traffic Light Protocol, see http://www.us-cert.gov/tlp.

Summary

Description

These files are related to SamSam ransomware. SamSam is a variety of ransomware based on the .NET framework.

For a downloadable copy of IOCs, see:

Submitted Files (6)

2b06d2abc87f51aa7b8451da16270003ceba57184b0dd5f244670873409c75b9 (winnetuse.exe)

427091e1888c2bf1f2e11a1010b3ab6c8634eda4ddc34d37202d401fbaa8989d (ss2.exe)

594b9b42a2d7ae71ef08795fca19d027135d86e82bc0d354d18bfd766ec2424c (ss2.stubbin)

a660cc6155b307c0957c4c6ea119a295a852d28097196d85f00f5517944a3dcb (SORRY-FOR-FILES.html)

bc53f513df363dd999ac855b53831b3b31ac5516a4bf8f324489710cf06955f0 (g04inst.bat)

da9c2ecc88e092e3b8c13c6d1a71b968aa6f705eb5966370f21e306c26cd4fb5 (sdgasfse.dll)

Domains (1)

jcmi5n4c3mvgtyt5.onion

Findings

594b9b42a2d7ae71ef08795fca19d027135d86e82bc0d354d18bfd766ec2424c

Tags

obfuscatedransomwaretrojan

Details
Namess2.stubbin
Size278032 bytes
Typedata
MD59202651c295369eb01cc7a10cd59adff
SHA1ff2f511009b2813af9d12c6103206828560869db
SHA256594b9b42a2d7ae71ef08795fca19d027135d86e82bc0d354d18bfd766ec2424c
SHA512547efea0c2407d1e2949e84fe107820a1efaab2eaddeaf60ceb8f23b53d635b7c86ceadb1e19c07432e51a3609d02f12aca99cb5e23b5d324febb67994f83a9c
ssdeep6144:gXNGATWMK0AlJgQpQXFvr0Cn8wyrQ4EeGiEb53fSEnetKA:gjDoWiUFe+NPSEnQH
Entropy7.999190
Antivirus
AhnlabBinImage/Obfuscated
AntiyGrayWare/Win32.Presenoker
CyrenTrojan.FTIO-1
McAfeeRansomware-SAMAS
SophosTroj/Samas-G
TrendMicroRansom_.67284F17
TrendMicro House CallRansom_.67284F17
Yara Rules

No matches found.

ssdeep Matches

No matches found.

Relationships
594b9b42a2...Contains427091e1888c2bf1f2e11a1010b3ab6c8634eda4ddc34d37202d401fbaa8989d
Description

This file is an encrypted data file with ".stubbin” extension. It contains the AES encrypted SamSam ransomware ss2.exe (1afc39b101a64c61b763fdf07fde1d55).

427091e1888c2bf1f2e11a1010b3ab6c8634eda4ddc34d37202d401fbaa8989d

Tags

dropperransomwaretrojan

Details
Namess2.exe
Size278016 bytes
TypePE32 executable (console) Intel 80386 Mono/.Net assembly, for MS Windows
MD51afc39b101a64c61b763fdf07fde1d55
SHA189fe55d2669e6c995b9a0d9ed5d5aa404d20713b
SHA256427091e1888c2bf1f2e11a1010b3ab6c8634eda4ddc34d37202d401fbaa8989d
SHA51235b066679ce733b0de20b79cb7570570164eb695307cbb96173bd7c4485b62a42e5b67caab8b9373e45b9cd9abe72ab0eb78960256420144b9f609c3734320f0
ssdeep1536:VLDPjQejqUjWMuX/28KIGsA/Nu4vlIXa5CjZwEclPcx6KtCNvmuxOfgQBAMyOk3t:V3Mexh8KIXAV9vOX6mz6ylgr
Entropy4.757791
Antivirus
AviraTR/Dropper.MSIL.Gen
BitDefenderGeneric.Ransom.SamSam.82D17683
ClamAVWin.Ransomware.Samsam-6425958-0
ESETa variant of MSIL/Filecoder.Samas.B trojan
EmsisoftGeneric.Ransom.SamSam.82D17683 (B)
IkarusTrojan-Ransom.Samas
McAfeeTrojan-FNEY!1AFC39B101A6
SophosTroj/Samas-L
SymantecRansom.SamSam
Yara Rules

No matches found.

ssdeep Matches

No matches found.

Relationships
427091e188...Contained_Within594b9b42a2d7ae71ef08795fca19d027135d86e82bc0d354d18bfd766ec2424c
427091e188...Downloadeda660cc6155b307c0957c4c6ea119a295a852d28097196d85f00f5517944a3dcb
Description

This file is a 32-bit Windows .NET compiled executable designed to encrypt victim system files for a ransom payment. This file is a variant of SamSam ransomware.

The ransomware accepts the following three arguments during runtime:

--Begin arguments--
"nonpenetrable"
"6"
"0.8"
--End arguments--

When executed, it searches and if installed will load a key file with a ".keyxml" extension into the %CurrentDirectory%. The key file contains a RSA public key in the following format:

--Begin RSA public key--
"<RSAKeyValue><Modulus>Base64 encoded RSA public key</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>"
--End RSA public key--

The key file was not available for analysis.

The ransomware searches for files to encrypt on all drives installed on the victim’s system. The malware avoids encrypting files with the following extensions and files in the following folders:

--Begin files--
"desktop.ini"
"g04inst.bat"
"ntuser.dat"
"search-ms"
.search-ms"
".exe"
".msi"
".lnk"
".wim"
".scf"
"microsoft\\windows"
"appdata"
.ini"
.sys"
".dll"                        
--End files--

It randomly generates the following keys for encrypting the target files:

--Begin randomly generated keys--
AES key (16 bytes)
AES IV (16 bytes)
Signature key (64 bytes) for SHA256 HMAC key calculation
--End randomly generated keys--

Displayed below is the code snippet for generating unique keys for each target file.

--Begin key generation--
public static string myff1(string plainFilePath, string encryptedFilePath, string manifestFilePath, string rsaKey)
{
byte[] signatureKey = encc.GenerateRandom(64); ===> HMAC key
byte[] key = encc.GenerateRandom(16); ; ==> Rijndael key
byte[] iv = encc.GenerateRandom(16); ; ==> Rijndael IV
encc.EncryptFile(plainFilePath, encryptedFilePath, key, iv, signatureKey, rsaKey);
return null;
--End key generation--

The malware reads the target file into memory and encrypts it using an AES algorithm in CBC mode by using the generated AES key. The encrypted data from the original file is stored into a newly created file. The newly created file has the same name as the original file, but with a ".weapologize" extension. The ransomware calculates a SHA-256 HMAC of the encrypted data of the file. The generated keys are encrypted using the RSA public key from the key file. The malware Base64 encodes and prepends the following data in XML format at the beginning of the encrypted file:

--Begin base64 encodes data--
AES key, encrypted with RSA public key
AES IV, encrypted with RSA public key
SHA-256H MAC of the encrypted file data
HMAC key, encrypted with RSA public key
--End base64 encodes data--

Displayed below is the code used to RSA encrypt and Base64 encode data prepended at the beginning of each encrypted file:

--Begin encrypting and encoding--
string text = Convert.ToBase64String(encc.RSAEncryptBytes(key, rsaKey));
string text2 = Convert.ToBase64String(encc.RSAEncryptBytes(iv, rsaKey));
string text3 = Convert.ToBase64String(encc.RSAEncryptBytes(signatureKey, rsaKey));
byte[] bytesFromString = encc.GetBytesFromString(string.Concat(new object[]
{
"<AAAAAAAAAAAAAAAAAAAAA>",
encc.nnnlllll,
"<AAA>",
text,
"</AAA>",
encc.nnnlllll,
"<AA>",
text2,
"</AA>",
encc.nnnlllll,
"<AAAAA>xPN1oBWSqfQgInnB6ydF204jiHN/uqljySnn1fkhqUk=</AAAAA>",
encc.nnnlllll,
"<AAAAAAAAAAAA>",
text3,
"</AAAAAAAAAAAA>",
encc.nnnlllll,
"<AAAAAAAAAAAAAAAAAA>",
fileInfo.Length,
"</AAAAAAAAAAAAAAAAAA>",
encc.nnnlllll,
"</AAAAAAAAAAAAAAAAAAAAA>"
}));
--End encrypting and encoding--

Following encryption, the original files are deleted and the ransomware note contents are DES encrypted and Base64 encoded in the malware. Displayed below is the hard-coded DES key and the IV used to decrypt the contents of the ransomware note.

--Begin DES key and IV--
DES KEY: 61 58 62 32 75 79 34 7A (aXb2uy4z)                
IV: 0C 15 2B 11 39 23 43 1B
--End DES key and IV--

It installs the ransomware note "SORRY-FOR-FILES.html" on the victim system. Next, the malware kills any open process, which file name contains "sql.”

a660cc6155b307c0957c4c6ea119a295a852d28097196d85f00f5517944a3dcb

Details
NameSORRY-FOR-FILES.html
Size3547 bytes
TypeHTML document, ASCII text, with very long lines, with no line terminators
MD5074e52525d5ec2b2af8675477180b5f0
SHA1631e5f4b9a3ba6855dd93dbdccb416337560491d
SHA256a660cc6155b307c0957c4c6ea119a295a852d28097196d85f00f5517944a3dcb
SHA51216d5cab293ffe44a8bfe247fc8f60167741d4a44cb12542b378cf26b689abcff95065ab44e4725b2ab3e85295925faa695bce1159d06211c1bf971d437398414
ssdeep96:2RPS2X4/vpRMdu4JW4Qy06pZu42yNSSa/kZLCXWQJxZEzQx:GulKuwscsR5
Entropy4.871033
Antivirus

No matches found.

Yara Rules

No matches found.

ssdeep Matches

No matches found.

Process List
ProcessPIDPPID
lsass.exe468(384)
iexplore.exe2628(2332)
explorer.exe1412(1368)
Relationships
a660cc6155...Downloaded_By427091e1888c2bf1f2e11a1010b3ab6c8634eda4ddc34d37202d401fbaa8989d
a660cc6155...Containsjcmi5n4c3mvgtyt5.onion
Description

This file is the ransom displayed to the victim. This ransomware note contains the ransom payment information and how to obtain the RSA private key to recover encrypted files. Displayed below are the embedded blog and Bitcoin addresses in the ransomware note:

--Begin blog and Bitcoin addresses--
blog address: "http://jcmi5n4c3mvgtyt5.onion/"
Bitcoin address: "1HbJu2kL4xDNK1L9YUDkJnqh3yiC119YM2"
--End blog and Bitcoin addresses--

Screenshots
Figure 1 - Screenshot of the ransom note

Figure 1 - Screenshot of the ransom note

2b06d2abc87f51aa7b8451da16270003ceba57184b0dd5f244670873409c75b9

Tags

ransomwaretrojan

Details
Namewinnetuse.exe
Size239104 bytes
TypePE32 executable (console) Intel 80386 Mono/.Net assembly, for MS Windows
MD55b168ad87a0de81c443656cc144df29a
SHA1c3cf36abda1463dbe81dc7a7283c6a089c922071
SHA2562b06d2abc87f51aa7b8451da16270003ceba57184b0dd5f244670873409c75b9
SHA512853eec13cba76de73361f1fb1e18d11ce3c1b9496f5e093d3050283643f569b659a5931b2092d8302cc8cfbfb69e4a6241461eed4c8931879818c4280af025cf
ssdeep1536:YM84wQNIdSpfYy1wDcCxqwDcCxqwDcCxqwDcCxqwDcCxqwDcCxWAAPtR8XKvfOxx:R2dHD3DD3DD3DD3DD3DD3v
Entropy5.041215
Antivirus
AhnlabTrojan/Win32.Occamy
AntiyTrojan/Win32.TSGeneric
BitDefenderGen:Variant.Razy.275811
ClamAVWin.Ransomware.Samsam-6482587-0
CyrenW32/Trojan.KJIQ-4456
ESETa variant of MSIL/Runner.J trojan
EmsisoftGen:Variant.Razy.275811 (B)
IkarusTrojan.SuspectCRC
K7Riskware ( 0040eff71 )
McAfeeRDN/Generic.dx
Microsoft Security EssentialsRansom:MSIL/Samas.D
NANOAVTrojan.Win32.Crypt.falsxr
NetGateTrojan.Win32.Malware
Quick HealTrojan.YakbeexMSIL.ZZ4
SophosMal/Kryptik-BV
SymantecTrojan Horse
TrendMicroTROJ_FR.5CBB1CDE
TrendMicro House CallTROJ_FR.5CBB1CDE
Zillya!Trojan.Crypt.Win32.42586
Yara Rules

No matches found.

ssdeep Matches

No matches found.

Packers/Compilers/Cryptors
Microsoft Visual C# v7.0 / Basic .NET
Relationships
2b06d2abc8...Related_Tobc53f513df363dd999ac855b53831b3b31ac5516a4bf8f324489710cf06955f0
Description

This file is a 32-bit Windows .NET compiled executable designed to search and loads the encrypted data file ss2.stubbin (9202651c295369eb01cc7a10cd59adff) on the victim's system. If ss2.stubbin exists, it will utilize Rijndael algorithm in the Class Library file ClassLibrary1.dll to decrypt the data file. Winnetuse.exe deletes the encrypted data file after decryption.

bc53f513df363dd999ac855b53831b3b31ac5516a4bf8f324489710cf06955f0

Tags

trojan

Details
Nameg04inst.bat
Size267 bytes
TypeASCII text, with CRLF line terminators
MD562e21431e87e8a21cf06319da7438f11
SHA1a4708853f4a7e4e242a236a433e9b5e8593f1090
SHA256bc53f513df363dd999ac855b53831b3b31ac5516a4bf8f324489710cf06955f0
SHA512f2f60c6eb6d96c025a34eb58e175866e15a806f9ec805793676cc60ede00dbfd55b9ade816c6148235e4fc34c4c412d91ae873d324032f1dbd17b09a7a539233
ssdeep6:JF1ZzANc4PgXsoFDVlAVyXHI+CIwZALICLA9X/1y/W:L1Jsc4PSJFDyyXo+Bb0L/1gW
Entropy4.884702
Antivirus
McAfeeBAT/Starter.h
Microsoft Security EssentialsRansom:BAT/Samas
SophosTroj/RansRun-A
SymantecTrojan.Malscript
Yara Rules

No matches found.

ssdeep Matches

No matches found.

Relationships
bc53f513df...Related_To2b06d2abc87f51aa7b8451da16270003ceba57184b0dd5f244670873409c75b9
Description

This file is a batch file designed to execute winnetuse.exe (5b168ad87a0de81c443656cc144df29a) with predefine arguments. Displayed are the arguments:
--Begin arguements--
Format: %myrunner% %password% %path% %totalprice% %priceperhost%
Sample: winnetuse.exe nvWvlIHNSzASiWhnMWCR nonpenetrable 6 0.8
--End arguements--

da9c2ecc88e092e3b8c13c6d1a71b968aa6f705eb5966370f21e306c26cd4fb5

Tags

ransomwaretrojan

Details
Namesdgasfse.dll
Size5632 bytes
TypePE32 executable (DLL) (console) Intel 80386 Mono/.Net assembly, for MS Windows
MD5f702153b68628eff973abb2912af0d22
SHA1138c3aae51e67db0c4134affae428fe91c0d1686
SHA256da9c2ecc88e092e3b8c13c6d1a71b968aa6f705eb5966370f21e306c26cd4fb5
SHA5127b5c3a6dcc30225874b70e9aa5df803d7796322e5c6654b0ace265b95b0134035384e113112a7a17b09e24dbceb71a22867424cfc1c660ec2ebb605583980dcd
ssdeep48:6/mWW45Rekl3tpEE4ln0LT8wVMM4W8i02+KU4AeyuNew0cxdn5Mla5GQ6bwN8ah:gBv3Z8we5i0/4Ae+2gMrG
Entropy3.968484
Antivirus
AhnlabTrojan/Win32.Samas
AntiyTrojan/Win32.AGeneric
AviraTR/Ransom.hlwsr
BitDefenderTrojan.GenericKD.30548303
ClamAVWin.Ransomware.Samsam-6482588-0
CyrenW32/Trojan.USJT-3730
ESETa variant of MSIL/Runner.N trojan
EmsisoftTrojan.GenericKD.30548303 (B)
IkarusRansom.MSIL.Samas
K7Riskware ( 0040eff71 )
McAfeeRDN/Generic.dx
Microsoft Security EssentialsRansom:MSIL/Samas.D
NANOAVTrojan.Win32.Ransom.ffqmxt
SophosTroj/Samas-F
SymantecRansom.SamSam
Systweaktrojan-spy.samas
TrendMicroTROJ_SAMAS.B
TrendMicro House CallTROJ_SAMAS.B
Zillya!Trojan.GenericKD.Win32.128339
Yara Rules

No matches found.

ssdeep Matches

No matches found.

PE Metadata
Compile Date2018-03-06 11:43:39-05:00
Import Hashdae02f32a21e03ce65412f6e56942daa
Company Namejkg kdjfhg dfkgdjf k,hh k
File Descriptionskudfkjg sjdfbsk hfkusdh fkjh
Internal Namesdgasfse.dll
Legal Copyrighthdf kjdfhgfk dhfkjhkh
Original Filenamesdgasfse.dll
Product Namekh vkjhd dfgk ghdfkjhkj
Product Version9.7.1.2
PE Sections
MD5NameRaw SizeEntropy
b85b73ffa6d2bc4679ee6ece174a93b1header5122.535489
12fe3b15c663fe9ed9480c352f9bded3.text30725.048626
9cf5eb0ba3d939001e41a98351a45be5.rsrc15362.577418
8ef9498de2781e9f674c2727ab3546c6.reloc5120.081539
Description

This file is .NET Class Library module designed for decrypting the encrypted data file with ".stubbin” extension using Rijndael encryption algorithm. Displayed are the Key and the initialization vector used for decryption.

--Begin key--
rijndael.Key = hdfgkhioiugyfyghdseertdfygu ==> 7E 7C C0 90 0A E8 7C 3B F1 38 6C 9E 7E 89 B8 29 10 76 C1 E4 FF 6C A3 F8 42 2B 9F 8C 83 7F AC FE
rijndael.IV = ghtrfdfdewsdfgtyhgjgghfdg ==> F1 38 6C 9E 7E 89 B8 29 C3 93 32 02 C5 A0 08 10
--End key--

jcmi5n4c3mvgtyt5.onion

URLs
  • http://jcmi5n4c3mvgtyt5.onion/
Relationships
jcmi5n4c3mvgtyt5.onionContained_Withina660cc6155b307c0957c4c6ea119a295a852d28097196d85f00f5517944a3dcb
Description

The domain was identified in the ransom note.

Relationship Summary

594b9b42a2...Contains427091e1888c2bf1f2e11a1010b3ab6c8634eda4ddc34d37202d401fbaa8989d
427091e188...Contained_Within594b9b42a2d7ae71ef08795fca19d027135d86e82bc0d354d18bfd766ec2424c
427091e188...Downloadeda660cc6155b307c0957c4c6ea119a295a852d28097196d85f00f5517944a3dcb
a660cc6155...Downloaded_By427091e1888c2bf1f2e11a1010b3ab6c8634eda4ddc34d37202d401fbaa8989d
a660cc6155...Containsjcmi5n4c3mvgtyt5.onion
2b06d2abc8...Related_Tobc53f513df363dd999ac855b53831b3b31ac5516a4bf8f324489710cf06955f0
bc53f513df...Related_To2b06d2abc87f51aa7b8451da16270003ceba57184b0dd5f244670873409c75b9
jcmi5n4c3mvgtyt5.onionContained_Withina660cc6155b307c0957c4c6ea119a295a852d28097196d85f00f5517944a3dcb

Recommendations

NCCIC would like to remind users and administrators to 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 thumbdrives, external drives, CDs, etc.).
  • Scan all software downloaded from the Internet prior to executing.
  • Maintain situational awareness of the latest threats and implement appropriate ACLs.

Additional information on malware incident prevention and handling can be found in NIST's Special Publication 800-83, Guide to Malware Incident Prevention & Handling for Desktops and Laptops.

Contact Information

NCCIC continuously strives to improve its products and services. You can help by answering a very short series of questions about this product at the following URL: https://us-cert.gov/forms/feedback/

Document FAQ

What is a MIFR? A Malware Initial Findings Report (MIFR) is intended to provide organizations with malware analysis in a timely manner. In most instances this report will provide initial indicators for computer and network defense. To request additional analysis, please contact US-CERT and provide information regarding the level of desired analysis.

What is a MAR? A Malware Analysis Report (MAR) is intended to provide organizations with more detailed malware analysis acquired via manual reverse engineering. To request additional analysis, please contact US-CERT and provide information regarding the level of desired analysis.

Can I edit this document? This document is not to be edited in any way by recipients. All comments or questions related to this document should be directed to the NCCIC at 1-888-282-0870 or soc@us-cert.gov.

Can I submit malware to NCCIC? Malware samples can be submitted via three methods:

NCCIC encourages you to report any suspicious activity, including cybersecurity incidents, possible malicious code, software vulnerabilities, and phishing-related scams. Reporting forms can be found on US-CERT's homepage at www.us-cert.gov.

Revisions

  • December 3, 2018: Initial version

This product is provided subject to this Notification and this Privacy & Use policy.

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