CVE-2021-45837

published 2022-04-25

CVE-2021-45837: It is possible to execute arbitrary commands as root in Terramaster F4-210, F2-210 TOS 4.2.X (4.2.15-2107141517) by sending a specifically crafted input to…

Priority P1 85 critical 9.8 CVSS 3.1

AV N AC L PR N UI N S U C H I H A H

ITW EXPLOIT VulnCheck KEV

It is possible to execute arbitrary commands as root in Terramaster F4-210, F2-210 TOS 4.2.X (4.2.15-2107141517) by sending a specifically crafted input to /tos/index.php?app/del.

Affected

1 ranges

Vendor	Product	Version range	Fixed in
terra-master	tos	—	—

Detection & IOCs extracted from sources · hover to see the quote

url /tos/index.php?app/del↗

url /module/api.php?mobile/webNasIPS↗

• → Monitor HTTP requests targeting `/tos/index.php?app/del` with crafted POST/GET parameters, which is the RCE trigger endpoint for CVE-2021-45837. ↗
• → Detect reconnaissance/hash-harvesting requests to `/module/api.php?mobile/webNasIPS`, which is used in the exploit chain (CVE-2021-45839) to obtain the administrator password hash and MAC address prior to RCE. ↗
• → Alert on self-signed/forged session cookies constructed from a known MAC address and user password hash, indicative of CVE-2021-45841 session crafting used as a prerequisite step in this exploit chain. ↗
• → Flag unauthenticated login attempts using a null/empty password hash, which can be used to abuse the guest account as part of this exploit chain. ↗

• · The guest account is disabled by default on TerraMaster TOS; if enabled, it can be abused with a null/empty hash to gain unauthenticated access as a stepping stone in the exploit chain. ↗
• · Affected versions are TerraMaster TOS 4.2.15 and below (specifically confirmed on F4-210, F2-210 running TOS 4.2.X / 4.2.15-2107141517). Ensure patching covers all devices on these firmware lines. ↗

CVSS provenance

nvd v3.1 9.8 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd v2.0 10.0 CRITICAL AV:N/AC:L/Au:N/C:C/I:C/A:C

vulncheck 9.8 CRITICAL

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