Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 901bc839ae3339bb…

MALICIOUS

RTF / .DOC

10.5 KB
MD5: 30397de77b0be51f5eedd9d690b001ad SHA-1: ada028a6dc8e41d50caa5615c4ca7c718971e7fb SHA-256: 901bc839ae3339bb4466efd34956fca716e2f34e5d0d5eb1276c3f8b0fd36c0b
180 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File Execution: Malicious File T1566.001 Phishing: Spearphishing Attachment

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) by embedding an OLE object containing obfuscated Equation Editor code. The ".objupdate" directive forces the activation of this embedded object, triggering the exploit. The decoded object's class is identified as "EQUAtIoN.3", which is characteristic of this exploit. The primary intent appears to be the execution of arbitrary code, likely to download and run a secondary payload.

Heuristics 5

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • 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.
  • \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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001217.bin
a6db16bdd9afb6a54967c95b4f36c04b086b800afa2a30616c808001f2f7bbdc		 rtf-objdata-decoded RTF \objdata at offset 0x1217 1885 bytes

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