title: Freely Allocate Buffer on The Stack With Data From Socket
description:
As noted in the “VTPM.md” file in the eve documentation, “VTPM is a server listening on port
8877 in EVE, exposing limited functionality of the TPM to the clients.
VTPM allows clients to
execute tpm2-tools binaries from a list of hardcoded options”
The communication with this server is done using protobuf, and the data is comprised of 2
parts:
1. Header
2. Data
When a connection is made, the server is waiting for 4 bytes of data, which will be the header,
and these 4 bytes would be parsed as uint32 size of the actual data to come.
Then, in the function “handleRequest” this size is then used in order to allocate a payload on
the stack for the incoming data.
As this payload is allocated on the stack, this will allow overflowing the stack size allocated for
the relevant process with freely controlled data.
* An attacker can crash the system.
* An attacker can gain control over the system, specifically on the “vtpm_server” process
which has very high privileges.
problem types: CWE-789 Memory Allocation with Excessive Size Value
affected:
{
defaultStatus: unaffected
packageName: EVE OS
product: EVE OS
programFiles: https://github.com/lf-edge/eve/tree/master/pkg/vtpm/src/server.cpp
repo: https://github.com/lf-edge/eve
vendor:  LF-Edge, Zededa
versions:
lessThan: 9.5.0, status: affected, version: 3.0.0, versionType: release
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: ADJACENT_NETWORK
availabilityImpact: HIGH
baseScore: 9
baseSeverity: CRITICAL
confidentialityImpact: HIGH
integrityImpact: HIGH
privilegesRequired: LOW
scope: CHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
version: 3.1
]
format: CVSS
scenarios: GENERAL