Malicious RTF — malware analysis report

Static analysis result for SHA-256 477d903df4385c43…

MALICIOUS

RTF

4.5 KB First seen: 2019-09-30
MD5: 8ce46a830641f2eb993a469a09a282f0 SHA-1: b0b5a3826c43c6e96d8d3b608f1b63607d1e0a64 SHA-256: 477d903df4385c43aa881a82f438bb959ee9bc611080da052296210ef5ce0cd2
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains an embedded OLE object that triggers CVE-2017-11882 via Microsoft Equation Editor. This exploit allows for the execution of arbitrary code, likely to download and run a secondary payload. The file is classified as malicious due to this known vulnerability.

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_off000001ef.bin rtf-objdata-decoded RTF \objdata at offset 0x1EF 1885 bytes
SHA-256: b9b7ad24ffbe645d9b016c03d10bfacc042476cdc8dac62b833edf8d9ef6570c

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