Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 cccdfeafc4624556…

MALICIOUS

RTF / .DOC

2.09 MB
MD5: 68869c849f7db36925deecf9e9372671 SHA-1: 4fcc04690034349facb265b2cfbfb451635a92b0 SHA-256: cccdfeafc46245564bf382115620cc1ce820484aeedca4f4c9ca75fd57a77cbd
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1068 T1585.001 T1204.002 // a bit of wrong, but T1204.002 is User Execution: Malicious File T1204.002 User Execution: Malicious File

The sample is an RTF document that triggers CVE-2017-11882, a memory corruption vulnerability in the Microsoft Equation Editor. Heuristics indicate the presence of OLE objects and the presence of Equation.3 class, Equation Editor activation, and the use of  objupdate to force activation. No scripts or URLs were extracted from the sample, so the shellcode is likely contained within the embedded OLE objects.

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_off00001202.bin
bb3e56788983472e1e9ee0b6fe9a1b748779232de60f5944784b18227d85928b		 rtf-objdata-decoded RTF \objdata at offset 0x1202 27283 bytes
objdata_01_off0001cf33.bin
2f05c0110283d6d66817dd760d3b8c77e60c29eaf269a6c8a7c9412afdda699d		 rtf-objdata-decoded RTF \objdata at offset 0x1CF33 362865 bytes

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