Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 a3eac7c369d320eb…

MALICIOUS

RTF / .DOC

7.2 KB First seen: 2023-01-19
MD5: 90edc04d9d0975a42e5a510984a00e82 SHA-1: f0d8cadd216ad3997b7cf2581244696b9782b690 SHA-256: a3eac7c369d320eb3e4ae197ef4120fa432827dde00b6bc8067560beb5aa0647
180 Risk Score

Malware Insights

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

The sample is an RTF document that contains an embedded OLE object, specifically identified as an Equation Editor object. Heuristics indicate that this object is obfuscated and activated in a manner consistent with the CVE-2017-11882 vulnerability. This exploit is commonly used to download and execute arbitrary code, suggesting the document's primary purpose is to compromise the user's system.

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 1 \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_off000010ab.bin
6e56ced2e681db67a4a1fa96eee9cdb3b665c151f642c8e5271d0636f219c70d		 rtf-objdata-decoded RTF \objdata at offset 0x10AB 1475 bytes

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