cbcvebase.
CVE-2020-10884
published 2020-03-25

CVE-2020-10884: This vulnerability allows network-adjacent attackers execute arbitrary code on affected installations of TP-Link Archer A7 Firmware Ver: 190726 AC1750 routers…

PriorityP271high8.8CVSS 3.1
AVAACLPRNUINSUCHIHAH
EXPLOIT
EPSS
24.50%
97.6th percentile
This vulnerability allows network-adjacent attackers execute arbitrary code on affected installations of TP-Link Archer A7 Firmware Ver: 190726 AC1750 routers. Authentication is not required to exploit this vulnerability. The specific flaw exists within the tdpServer service, which listens on UDP port 20002 by default. This issue results from the use of hard-coded encryption key. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of root. Was ZDI-CAN-9652.

Affected

2 ranges
VendorProductVersion rangeFixed in
tp-linkac1750_firmware
tp-linkarcher_a7

Detection & IOCsextracted from sources · hover to see the quote

portUDP/20002
path/usr/bin/tdpServer
otherAES-128-CBC key: TPONEMESH_Kf!xn?
otherAES-128-CBC IV: 1234567890abcdef
url/webpages/app.1564127413977.manifest
  • Monitor for UDP traffic to port 20002 originating from LAN-side hosts targeting the router; this is the tdpServer service attack surface for CVE-2020-10884.
  • Detect exploitation attempts by looking for AES-128-CBC encrypted UDP payloads using the hardcoded key 'TPONEMESH_Kf!xn?' and IV '1234567890abcdef' on port 20002.
  • Command injection occurs via the 'slave_mac' field in tdpServer protocol packets; inspect decrypted UDP/20002 payloads for shell metacharacters in the slave_mac parameter.
  • Fingerprint vulnerable devices by issuing an HTTP GET to /webpages/app.1564127413977.manifest on port 80; a 200 response indicates a vulnerable firmware version.
  • All TP-Link Archer A7/C7 (AC1750) firmware versions up to (but excluding) releases 201029 and 201030 are exploitable; flag devices running firmware 190726 as high priority.
  • ·Exploitation is restricted to LAN-adjacent attackers only; the vulnerability cannot be triggered from the WAN side.
  • ·The hardcoded AES key and IV are used by the tdpServer service itself (not attacker-chosen), meaning any LAN host can craft valid encrypted packets without credentials.
  • ·A patch bypass was discovered in November 2020; the updated injection technique works on older firmware too, so patching to firmware 190726 alone is insufficient.

CVSS provenance

nvdv3.18.8HIGHCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
nvdv3.08.1HIGHCVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
nvdv2.05.8MEDIUMAV:A/AC:L/Au:N/C:P/I:P/A:P
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