cbcvebase.
CVE-2018-5002
published 2018-07-09

CVE-2018-5002: Adobe Flash Player versions 29.0.0.171 and earlier have a Stack-based buffer overflow vulnerability. Successful exploitation could lead to arbitrary code…

PriorityP278high7.8CVSS 3.1
AVLACLPRNUIRSUCHIHAH
KEVITW
CISA Known Exploited Vulnerabilitydue 2022-06-13
Exploited in the wild
EPSS
25.35%
97.7th percentile
Adobe Flash Player versions 29.0.0.171 and earlier have a Stack-based buffer overflow vulnerability. Successful exploitation could lead to arbitrary code execution in the context of the current user.

Affected

5 ranges
VendorProductVersion rangeFixed in
adobeflash_player<= 29.0.0.171
adobeflash_player_desktop_runtime<= 29.0.0.171
redhatenterprise_linux_desktop
redhatenterprise_linux_server
redhatenterprise_linux_workstation

Detection & IOCsextracted from sources · hover to see the quote

commandopenssl rsautl -decrypt -in enc_aes.bin -out dec_aes.bin -inkey private_key.pem
commandopenssl enc -nosalt -aes-128-cbc -d -in payload.bin -out decrypted_payload -K E4DF3353FD6D213E7400EEDA8B164FC0 -iv CC6FC77B877584121AEBCBFD4C23B67C
bytes
0x789C (zlib magic bytes)
  • The Flash downloader sends an HTTP POST request containing the RSA public key modulus (512-bit, hex-encoded) to the attacker's C2 server to retrieve the encrypted AES key and payload — monitor for HTTP POST requests with large hex-encoded numeric blobs from Flash/Office processes.
  • CVE-2018-5002 is triggered by specially crafted bytecode that bypasses Flash's bytecode verification, writing past the end of a buffer via an out-of-range pointer offset — SWF files with hand-crafted bytecode that fails standard verification are a key indicator.
  • Delivery vector is malicious Office documents with embedded Flash content distributed via targeted email — apply detections for Office documents spawning Flash Player processes or making network connections.
  • ·The AES key and IV extracted are specific to one observed sample from the PCAP; other CHAINSHOT deployments will use different randomly generated RSA key pairs and thus different AES keys/IVs per victim session.
  • ·The RSA key cracking was only feasible because the attacker used a weak 512-bit key; this decryption approach will not apply if the attacker upgrades to a longer key length.
  • ·The first 2 bytes of the POST modulus blob are a version selector (e.g., to retrieve 32-bit vs 64-bit payload) and must be stripped before factoring the modulus.

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
nvdv2.010.0CRITICALAV:N/AC:L/Au:N/C:C/I:C/A:C
osv7.8HIGH
vulncheck7.8HIGH
cisa7.8HIGH
vendor_redhat7.8HIGH
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