Network Working Group A. Dulaunoy Internet-Draft J-L. Huynen Intended status: Informational CIRCL Expires: 20 March 2022 16 September 2021 hashlookup format draft-dulaunoy-hashlookup-format-01 Abstract This document describes the hashlookup output format used to express meta information of hash values seen in databases of known files. The output description includes a common semantic. The hashlookup format is used by public and private digital forensics investigations services. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 20 March 2022. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Dulaunoy & Huynen Expires 20 March 2022 [Page 1] Internet-Draft hashlookup format September 2021 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Conventions and Terminology . . . . . . . . . . . . . . . 2 2. Format . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Rational . . . . . . . . . . . . . . . . . . . . . . . . 3 2.3. Fields Format . . . . . . . . . . . . . . . . . . . . . . 3 2.3.1. Cryptographic hashing . . . . . . . . . . . . . . . . 3 2.3.2. Fuzzy hashing (Context Triggered Piecewise Hashing) . . . . . . . . . . . . . . . . . . . . . . 4 2.3.3. Additional fields . . . . . . . . . . . . . . . . . . 4 2.3.4. Relationships fields . . . . . . . . . . . . . . . . 5 2.4. Sample hashlookup output . . . . . . . . . . . . . . . . 5 2.4.1. Binary file . . . . . . . . . . . . . . . . . . . . . 5 2.4.2. Binary file - package . . . . . . . . . . . . . . . . 6 3. Implementation . . . . . . . . . . . . . . . . . . . . . . . 6 4. Security Considerations . . . . . . . . . . . . . . . . . . . 7 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 7. Normative References . . . . . . . . . . . . . . . . . . . . 7 8. Informative References . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 1. Introduction Digital forensics is a critical field in information security and especially incident response. Providing intelligence about known set of files is crucial to avoid wasting efforts while conducting digital investigations. hashlookup format provides a common output format for diverse known databases of file hashes. Those databases are, for example, the NIST National Software Reference Library (NSRL) or Known File Filter (KFF) lists used in digital forensics software. 1.1. Conventions and Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 2. Format Dulaunoy & Huynen Expires 20 March 2022 [Page 2] Internet-Draft hashlookup format September 2021 2.1. Overview The hashlookup format follows the JSON [RFC8259] format. The intent of this output to be easily parsed by machines or generated by software in stream mode. Each JSON object is expressed on a single line to be processed by the client line-by-line. Examples of JSON output are presented below. 2.2. Rational The main goal of the hashlookup format is to share common fields and to easily combine results from different sources. There are different reference library which are used in different uses-cases such as: * Conducting digital forensic investigation and trace the origin of released software distribution * Tracing the origin and especially the overlap between software distribution to conduct copyright assessment * Improve and support cyber supply chain and its risk management 2.3. Fields Format As there is a wide variety of sources with various granularities of information available, the hashlookup format has been made quite lax regarding the mandatory fields. The only condition is to have at least one cryptographic hash or fuzzy hashing value MUST be present in an hashlookup JSON object. The following sections define the JSON fields which are permissible. The values in the key-value pairs are strings. 2.3.1. Cryptographic hashing The cryptographic hashing value MUST be a JSON string. The string represents the hashed value of the file represented. The string MUST be the hexadecimal representation of the hash in upper case. * "MD5" * "SHA-1" * "SHA-256" Dulaunoy & Huynen Expires 20 March 2022 [Page 3] Internet-Draft hashlookup format September 2021 2.3.2. Fuzzy hashing (Context Triggered Piecewise Hashing) The fuzzy hashing value MUST be a JSON string. The string represents the hashed value of the file represented. * "TLSH" * "SSDEEP" 2.3.3. Additional fields Additional fields MAY be present to describe additional metadata from the file. The value MUST be a JSON string. * "FileName": Filename of the hashed file (NSRL) * "FileSize": FileSize of the hashed file (NSRL) * "CRC": CRC of the hashed file (NSRL) * "SpecialCode": Special code of the hashed file (NSRL) as described in [NSRL-RDS] * "OpSystemCode": OpSystemCode of the hashed file (NSRL) as described in [NSRL-RDS] * "ProductCode": ProductCode of the hashed file (NSRL) as described in [NSRL-RDS] * "PackageName": Package Name of the hashed file as seen in metadata of Debian pakage format, RPM or similar package managers (CIRCL) * "PackageMaintainer": Package maintainer of the hashed file as seen in metadata of the Debian package format, RPM or similar package managers (CIRCL) * "PackageSection": Package section of the hashed file as seen in the metadata of the Debian package format, RPM or similar package managers (CIRCL) * "PackageVersion": Package version of the hashed file as seen in the metadata of the Debian package format, RPM or similar package managers (CIRCL) * "KnownMalicious": List of source considering the hashed file as being malicious (CIRCL) * "tar:gname": Group name used to create the Tar archive Dulaunoy & Huynen Expires 20 March 2022 [Page 4] Internet-Draft hashlookup format September 2021 * "tar:uname": User name used to create the Tar archive 2.3.4. Relationships fields Two OPTIONAL fields "parents" and "children" MAY be present to represent the relationships with other hashlookup objects. The "parent" or "children" field MUST be a JSON array. The value is a JSON string representing one the hashing algorithms. The "SHA-1" is the RECOMMENDED algorithm for the relationship. Other algorithms MAY be used if SHA-1 is not available. 2.4. Sample hashlookup output 2.4.1. Binary file Dulaunoy & Huynen Expires 20 March 2022 [Page 5] Internet-Draft hashlookup format September 2021 { "CRC32": "B4DD44A4", "FileName": "./bin/ls", "FileSize": "110080", "MD5": "945FEDB3A3C290D69F075F997E5320FF", "OpSystemCode": { "MfgCode": "1006", "OpSystemCode": "362", "OpSystemName": "TBD", "OpSystemVersion": "none" }, "ProductCode": { "ApplicationType": "Operating System", "Language": "English", "MfgCode": "534", "OpSystemCode": "599", "ProductCode": "163568", "ProductName": "Vinux ", "ProductVersion": "5.1" }, "SHA-1": "5848386F77B4C60319C68B69C4594E29959381A2", "SHA-256": "08AC13B08BFE4407E0F0C2E12E7F5B1B5E77EB817349A5EA1D836E83CD5ACB13", "SpecialCode": "", "parents": [ { "FileSize": "1090622", "MD5": "10A2318BE86F38A6ED113E16AABAA76B", "PackageDescription": "GNU core utilities\n This package contains the basic file, shell and text manipulation\n utilities which are expected to exist on every operating system.\n .\n Specifically, this package includes:\n arch base64 basename cat chcon chgrp chmod chown chroot cksum comm cp\n csplit cut date dd df dir dircolors dirname du echo env expand expr\n factor false flock fmt fold groups head hostid id install join link ln\n logname ls md5sum mkdir mkfifo mknod mktemp mv nice nl nohup nproc od\n paste pathchk pinky pr printenv printf ptx pwd readlink rm rmdir runcon\n sha*sum seq shred sleep sort split stat stty sum sync tac tail tee test\n timeout touch tr true truncate tsort tty uname unexpand uniq unlink\n users vdir wc who whoami yes", "PackageMaintainer": "Ubuntu Developers ", "PackageName": "coreutils", "PackageSection": "utils", "PackageVersion": "8.21-1ubuntu5.4", "SHA-1": "F335B669CCB7BA8A2FC8FAF315B1B4BFF9D4217F", "SHA-256": "07995A739DAEBD60297F0E9C2B44DFAB0C735A0FE08FACC097ECE06BB4B9FA0B" } ] } 2.4.2. Binary file - package {"FileSize": "1090622", "MD5": "10A2318BE86F38A6ED113E16AABAA76B", "PackageDescription": "GNU core utilities\n This package contains the basic file, shell and text manipulation\n utilities which are expected to exist on every operating system.\n .\n Specifically, this package includes:\n arch base64 basename cat chcon chgrp chmod chown chroot cksum comm cp\n csplit cut date dd df dir dircolors dirname du echo env expand expr\n factor false flock fmt fold groups head hostid id install join link ln\n logname ls md5sum mkdir mkfifo mknod mktemp mv nice nl nohup nproc od\n paste pathchk pinky pr printenv printf ptx pwd readlink rm rmdir runcon\n sha*sum seq shred sleep sort split stat stty sum sync tac tail tee test\n timeout touch tr true truncate tsort tty uname unexpand uniq unlink\n users vdir wc who whoami yes", "PackageMaintainer": "Ubuntu Developers ", "PackageName": "coreutils", "PackageSection": "utils", "PackageVersion": "8.21-1ubuntu5.4", "SHA-1": "F335B669CCB7BA8A2FC8FAF315B1B4BFF9D4217F", "SHA-256": "07995A739DAEBD60297F0E9C2B44DFAB0C735A0FE08FACC097ECE06BB4B9FA0B", "children": ["9799864E326E9DB68121471C6E72EA45152BD2C8", "A880A1F35311A7D34C9B2CA10418BD6EE94EFF58", "3E9FE88BBFE594A701522C2BAF65E209FDF7EFD9", "E03605C7911BF75BE61E54FB922B11DCF1EAAFF9", "181A05F9D249BC99FB684984C631F149CC96990C", "7EF60EF3D83B352ACC9AF996ACDC7BE3DE955705", "C687BCF2FCB74F649163AAB837C15D5800D80B31", "168CA019316332AC0A01472BDF8769801F613DCA", "6645E63EC4411B54287CB0C1321160E44B05FB87", "1989E263AF6ACF6E2869D0B4CF9433E240213C4E", "DEDFD0DA98EA7D07A5B1C7D16EACDCD0154C79B9", "C1A0868024358B0C2F0A2991BD4676B70EBF66F3", "69952AAC37372161F66DA9B07FE0BE5263A9249F", "C03D2998DE9E4332DC91586F00DAC3CA5F4761C3", "E558E7B478FAC50CCACE0E6BE28CAA19FBC74D4E", "08E3AFA387417CB0DA343837D68374A4AB8D915F", "46750D0726DB8D8E4DF870B1060E2414B64164E9", "47A2C7B8518F7E790B097785E25C8E5909AE8A39", "9D8E3FD5BE0D04815F5B0606E94C3B7C29CC8788", "FCAD50919AF0544353E950D1B52E6E2C7B98854B", "CFDE9C955B1E774EF72FB2B4A3E180EADF4CD3D0", "95C37C6826FF0C4E1C17D08285D346EE643343C0", "B35FB1B6DCEC924603F8A86677DBB0D54F5B3C18", "F8592BBAF848DEF6DC26266B15246C50D45C2095", "FF43C49690FF5E5D05CA59D7E66CEEA7E3CE00D0", "903FA7065E10EA3ED8D07598715E7AA73C38BA5A", "64D49DB459A03800399A5BB8CFFE979A604959CF", "688FCF82E39A1C44424FE9F440B69B341FC8B6E2", "0A073CD0BBFB5A33F539003F85E4D90C4CA3F2BD", "C158DC6563C36EA34408E1A36D9786A8CD95FD22", "6ECEBFE6C408316371834A52A037D91EB5BD2A1E", "2411EE623576B90A80AF6B50C47E6186F8AB6308", "2592E88C4FD1BD34207E480AEF99508090370945", "3904F363902225998E2222D67D20D01579461C15", "76FCB8813682CC8697AF1E5C6DDD5FB1DFDEA23C", "D461D21F9994EA40C68651BCA6A6D07F43A551C4", "AEE56A85B66D037EAD8C2D630194C8C46E5C061A", "69AD64E3E922A40EC3372C5DBEE57E8ABE486227", "1348C730C44DF01C0D49DB6084B5736A1D7A3BBC", "E0A97820A852729E236F7524CC23060C7BD7638E", "BF2AAAEDAB78605C43FF12450381C07C15A01D06", "071E525B285AD74B3884F1661D857E8491D2C622", "087204A60FDF211A545A5B8B900F23C0AA118333", "5848386F77B4C60319C68B69C4594E29959381A2", "E19EC3D5E7B9AEC5320CE69FAE5A61EAA7AB2143", "A57FB1F8263E8AA32B36B0D08CDA214E55DE9202", "E8FC405D941E589AA1BAB01E05AD321A049B7775", "A9DB474B1F26FAF5E01B7D545D9CA66269487053", "5E49F9779E165B4EEE965914FECBB8F7D78C59C8", "B90EAF06CF7C6F829B5D671936B59052797F78AC", "90772F507D44570ECDF615B4C232F19FC6DD9D0D", "8025FBA333B4ADCE8EFCAD284541F38C41DA09DE", "F899AA531C826504B9B494C8EA5E4532313210A0", "6AE02146CEC01123843393817D352A805227807D", "3F9E530FB7E8C37E53FFCB1ECF977E00C25F224E", "416FD291494F58795077E5EE064D92329E15DE0E", "9A9A76DA8EC26B5AA3B1F35C434466291424718F", "731D8E470227AC5AAD8432EC123984B9D052B7A0", "EBE777F05B387155604065AD4BED08D2EA3CB8B8", "787ACF5E6A560B4AEB008111F701A730AADF2EC7", "AA6F74DAD038A0DFCD4D64A002482F40BB732F10", "16C68C5BD71D93E06C2D8FC7F0F0F73954C6D7C3", "4AA2F5D8C293531D72137EAE6F71044CD46B5AD7", "99F256008B4847D716492E9763D03D049EEECE6C", "3244B00D11BA9997243A3C2D3108FC915A4BA042", "9C7C38A4B21AACB6DC51AB8A97F6CDE6704ACCB6", "781A6E4FE0CB8167CE423FC476240BDED698D676", "A71230EDAE1E5D354C672E7AB1CE92BC6059EC7C", "ACBD8B51B76889C2F55820E1C32BB26FBF67C441", "7C394AF4519CE500161DEB17857B9C057B7C74B3", "7AB1711D45DB3752B7CBE446D2E0E62D77E75EE3", "8CD8BD2875A68CD5E01F4A071B3F39F5B725B2B6", "D5FF3DB00A37075C07878A718852AFE539C7610D", "1B56B7A2684EB25235DE1708ED1371CD7879540F", "53D8A8EF35DA82BB6118BF9D8BF1ED404FC383C9", "47392375E355F56961CA42E1CFB6B98BBD484D4C", "DCBD08101D550F76DCC1B7507B152734B6F7CE7C", "F8DF08929A667BED6D7086812C319DB522E8292C", "1FB274F0883E0075D398806ACD0FA765F1118C20", "583A638A220E6FD91569F4E263771D4F89F2CC67", "39698F9FA30AE6990ACDF69280B682D90705EC32", "DE762C72E9720DB70C1897C3E0FC9C8C7D160210", "283DD2D206477E4081911F6B83950EE76503EBAD", "A7C8E7F93AE9E86A7836238644274CD73C75F5A7", "A03537A232503853D9D4C30C732CFB5F12913D93", "3F4D980B4870D5A6EB3DF334CA49C5566000C97F", "C028089A484BA0AD0166281B58DEBE0C99E5B4E7", "4A46ECF0336D55076B1C72D2459139F85DF7236C", "DF9C0BDE30B1E2C8FAF8E35CBBD3672C0AE0DFDA", "29E52E423E17C0CE93D38AA8380B0A3AF137BC7E", "BA5FD03FF246DE181DDCAA744DC2AEF4D3711762", "FE7D945A453A276E1CD005AB7A1E177D48C63A86", "DD5A833CD33617F4DCDA0220809D41FA9B1EBFC7", "4017F5B69FBB5064E51A95C856437859BA6CBA83", "427B32F83A3FC5CA0813CBACE975ECA2D6AD918B", "8F16C526AF56EF4369611718463AD4975811DD20", "FC1C867CC2D89C5985C8CB833A3980915AF7E1A1", "EB3FCFD28830CCED7C6BAA04908F574EA4F2A61F", "410D1E55EE08EF6BD7DE39DE80A02981BAF151D1", "988B560C670EDD9E2AEEE6C1D6DE584518CC57F5", "F26ABF496FC9940BB06CD4CEC3D892CF2E426B6A", "22AC7B8CA7324408A18BB95FB55AAE9E5EA85785", "F3E09D476BB01366D740EFF92453AC73C8356F43", "6DD5ACA0C43EF39FD7FFAFEEDE46986985BC84DE", "E38EDB72D805F466556C8BB796EA729CBCC04245", "D6C447B56B702869E9B429A7B47E1CE3B57BED9A", "64E23452FA980EB5DD1D4375071CB6124CF9B196", "7883EB75715603F1B89449BE617F91C65698DF38", "C328540F2D947D50EF02AC958C0DCDB51CCA0DD0", "2AC91E34FE455B026B537EA8FBA86E69E251CEE4", "672D844C60553F9B3DB9844DC29DDF49BC426F45", "EDB7ED42160C95BA2C9DD4C1E87577BD85DFE5FB", "6F4DF90B509C9392A180D7C76BB0058D4C44A4BD", "1C75F8FAF710C17B87DFD75D8390F2F2F7AF6400", "C02435F5BE0DB85C12B47E33644322631CBE7CCA", "B0C07FAC1BA571EC3054D79C40181D99CB4D01ED", "CA0B3EBCD75D8799863ADDB66E9BD378A3B88F8E", "521E4CC97D2372F821F75DB03A26938F923C002C", "CFE1C6F349F1F0611CFD3B6DD0E60EB135D7D798", "DFC1F4C951F6E09B6CFCA69127BE483279A9B5F9", "6E957B4561B081DA16886751D729170975D860BE", "A570E581D7E1D5308E88154967C3BDE3593DA50D", "99CCB36AE5BA1B6EF528C3477CDB1185744C8DA7", "A07770FC93BAA888407523BB58EE9CE97C94DB02", "56035A58036F19A2C9D312BF2730C7F970B380CA", "2C3D857765A05AF072146796B07D6A063C0B7224", "4BD3020D460E50386297CE14F9AD85B7278F9A73", "7F8BF064B328BE934582341857413CE7A387CB81", "403645FFD3A5B16F3E558947C1854FAC180C1E92", 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Implementation A public hashlookup service [HASHLOOKUP-SERVICE] is provided by CIRCL and accessible as a ReST HTTP API. A software back-end implementation which produces a hashlookup format output is available [HASHLOOKUP-SERVER]. Dulaunoy & Huynen Expires 20 March 2022 [Page 6] Internet-Draft hashlookup format September 2021 4. Security Considerations hashlookup results events might contain sensitive or confidential information. Adequate access control and encrypted transport layer shall be implemented to ensure the confidentiality of the hashlookup results. hashlookup results don't imply a specific assumption concerning the maliciousness or non-maliciousness of a file. hashlookup only provides the information about the presence of a file in a specific set, known source or database. 5. Acknowledgements The authors wish to thank all the users of the CIRCL hashlookup services for their feedback. 6. References 7. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, DOI 10.17487/RFC8259, December 2017, . 8. Informative References [HASHLOOKUP-SERVER] Dulaunoy, A., "hashlookup-server is a minimal and fast open source server (ReST/API) to lookup quickly hash value from large dataset.", . [HASHLOOKUP-SERVICE] CIRCL.LU, "CIRCL hash lookup is a public API to lookup hash values against known database of files.", . [NSRL-RDS] NIST.gov, "Data Formats of the NSRL Reference Data Set (RDS) Distribution", . Dulaunoy & Huynen Expires 20 March 2022 [Page 7] Internet-Draft hashlookup format September 2021 Authors' Addresses Alexandre Dulaunoy Computer Incident Response Center Luxembourg 16, bd d'Avranches L-L-1160 Luxembourg Luxembourg Phone: +352 247 88444 Email: alexandre.dulaunoy@circl.lu Jean-Louis Huynen Computer Incident Response Center Luxembourg 16, bd d'Avranches L-L-1160 Luxembourg Luxembourg Phone: +352 247 88444 Email: jean-louis.huynen@circl.lu Dulaunoy & Huynen Expires 20 March 2022 [Page 8]