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GHSA-88h9-77c7-p6w4
No affected components available
Summary
A vulnerability was identified in the evervault-go SDK’s attestation verification logic that may allow incomplete documents to pass validation. This may cause the client to trust an enclave operator that does not meet expected integrity guarantees.
The exploitability of this issue is limited in Evervault-hosted environments as an attacker would require the pre-requisite ability to serve requests from specific evervault domain names, following from our ACME challenge based TLS certificate acquisition pipeline.
The vulnerability primarily affects applications which only check PCR8. Though the efficacy is also reduced for applications that check all PCR values, the impact is largely remediated by checking PCR 0, 1 and 2.
Patches
The identified issue has been addressed in version 1.3.2 by validating attestation documents before storing in the cache, and replacing the naive equality checks with a new SatisfiedBy check.
Workarounds
If you are using evervault-go to attest Enclaves that are hosted outside of Evervault environments and cannot upgrade:
- Modify your application logic to fail verification if PCR8 is not explicitly present and non-empty
- Add custom pre-validation to reject documents that omit any required PCRs.
POC
package evervault
import (
"testing"
"github.com/evervault/evervault-go/attestation"
"github.com/stretchr/testify/assert"
"github.com/hf/nitrite"
)
func TestVulnerableCompare(t *testing.T) {
assert := assert.New(t)
// arrange
expectedPCRs := []attestation.PCRs{
attestation.PCRs{
PCR0:
"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001",
PCR1:
"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002",
PCR2:
"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000003",
PCR8:
"000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000004",
},
}
actualDocument := nitrite.Document {}
actualDocument.PCRs = map[uint][]byte{
10: make([]byte, 32),
}
// act
v := verifyPCRs(expectedPCRs, actualDocument)
// assert
// Verify should not pass but it does
assert.Equal(true, v)
}
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs high-level or administrative privileges. No user interaction is needed for the attacker to exploit this vulnerability. The vulnerability can affect other systems as well, not just the initial system. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data.
Exploitation activity has been observed. Apply available patches or mitigations urgently.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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