Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b4121583939ba4be…

MALICIOUS

RTF / .DOC

1.96 MB
MD5: 6cfdfe218629abbf3f5ff95ca9ed0878 SHA-1: 93f8bf725f4f5406c7f134a2f4ea9983cf121e12 SHA-256: b4121583939ba4bedab89aa2624d82217ef498eafa228dce5b604f7f5b1dd2bf
180 Risk Score

Malware Insights

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

The RTF document contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability related to Equation Editor. The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics strongly indicates exploitation of this known vulnerability. The `RTF_OBJUPDATE` heuristic suggests that the embedded object is automatically activated, leading to the execution of malicious code. The decoded object data, though truncated, contains what appears to be obfuscated VBScript, likely intended to download and execute a second-stage payload.

Heuristics 5

  • 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.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • \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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001116.bin
f23035ced4f128effebbc175c6c180d0b31d4bb493c7bd3641c7e27962f2f07d		 rtf-objdata-decoded RTF \objdata at offset 0x1116 25565 bytes
objdata_01_off00019197.bin
ac9bfb081d4e3f91c1d530b09d33124ea631b81e03f3efc0b3eee9f29b094bb3		 rtf-objdata-decoded RTF \objdata at offset 0x19197 463381 bytes

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