Malicious RTF — malware analysis report

Static analysis result for SHA-256 41f0757ca4367f22…

MALICIOUS

RTF

316.9 KB Created: 2019-04-27 22:42:00 Authoring application: Microsoft Word 11.0.5604 First seen: 2021-02-20
MD5: f34514118eb4689560cd6c0c654f26d9 SHA-1: 6e670a837970a1fb4161d77d5f720d318d7e4dbc SHA-256: 41f0757ca4367f22b0aece325208799135c96ebe1dcafcd752d3f3c8dd4a5ccf
340 Risk Score

Heuristics 8

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • CVE-2018-0798 — Equation Editor Matrix record overflow critical CVE exact CVE_2018_0798
    RTF contains hex-encoded MTEF Matrix record exploit signature (NOP-sled 0x60 + padding 0x61 + return address 0x0BFB). CVE-2018-0798 exploits a stack buffer overflow in EQNEDT32.EXE's Matrix record parser and affected Equation Editor broadly, including builds patched for CVE-2017-11882. Widely used by APT groups (Conimes, KeyBoy, Emissary Panda, Rancor).
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • ClamAV: Rtf.Dropper.Agent-6964405-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-6964405-0
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Package object class high RTF_OBJCLASS_PACKAGE
    OLE Package object — can wrap arbitrary files
  • OLE object data medium RTF_OBJDATA
    RTF contains 3 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00010424.bin rtf-objdata-decoded RTF \objdata at offset 0x10424 116976 bytes
SHA-256: 690872911f67d8cef9154cd7e234ec48c787f0ad82ef63b67b7ebe5fdd02545f
objdata_01_off0004963a.bin rtf-objdata-decoded RTF \objdata at offset 0x4963A 11842 bytes
SHA-256: 82a0e9d2b46fe974ae1d3298ffd405eb8e6ea8fda7665fef57d4e0d76c604d9d
objdata_02_off0004964c.bin rtf-objdata-decoded RTF \objdata at offset 0x4964C 35 bytes
SHA-256: d0771b17e6418e479f528fc4aa124822669975a78f8dc3e35cdc4b0f7c212c4e

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