diff --git a/builtin/credential/aws/pkcs7/ber.go b/builtin/credential/aws/pkcs7/ber.go
index 585256739..19d9fa7df 100644
--- a/builtin/credential/aws/pkcs7/ber.go
+++ b/builtin/credential/aws/pkcs7/ber.go
@@ -175,7 +175,7 @@ func readObject(ber []byte, offset int) (asn1Object, int, error) {
 	if offset > berLen {
 		return nil, 0, errors.New("ber2der: cannot move offset forward, end of ber data reached")
 	}
-	hack := 0
+	indefinite := false
 	if l > 0x80 {
 		numberOfBytes := (int)(l & 0x7F)
 		if numberOfBytes > 4 { // int is only guaranteed to be 32bit
@@ -197,14 +197,7 @@ func readObject(ber []byte, offset int) (asn1Object, int, error) {
 			}
 		}
 	} else if l == 0x80 {
-		// find length by searching content
-		markerIndex := bytes.LastIndex(ber[offset:], []byte{0x0, 0x0})
-		if markerIndex == -1 {
-			return nil, 0, errors.New("ber2der: Invalid BER format")
-		}
-		length = markerIndex
-		hack = 2
-		debugprint("--> (compute length) marker found at offset: %d\n", markerIndex+offset)
+		indefinite = true
 	} else {
 		length = (int)(l)
 	}
@@ -220,6 +213,9 @@ func readObject(ber []byte, offset int) (asn1Object, int, error) {
 	debugprint("--> content end   : %d\n", contentEnd)
 	debugprint("--> content       : % X\n", ber[offset:contentEnd])
 	var obj asn1Object
+	if indefinite && kind == 0 {
+		return nil, 0, errors.New("ber2der: Indefinite form tag must have constructed encoding")
+	}
 	if kind == 0 {
 		obj = asn1Primitive{
 			tagBytes: ber[tagStart:tagEnd],
@@ -228,14 +224,25 @@ func readObject(ber []byte, offset int) (asn1Object, int, error) {
 		}
 	} else {
 		var subObjects []asn1Object
-		for offset < contentEnd {
+		for (offset < contentEnd) || indefinite {
 			var subObj asn1Object
 			var err error
-			subObj, offset, err = readObject(ber[:contentEnd], offset)
+			subObj, offset, err = readObject(ber, offset)
 			if err != nil {
 				return nil, 0, err
 			}
 			subObjects = append(subObjects, subObj)
+
+			if indefinite {
+				terminated, err := isIndefiniteTermination(ber, offset)
+				if err != nil {
+					return nil, 0, err
+				}
+
+				if terminated {
+					break
+				}
+			}
 		}
 		obj = asn1Structured{
 			tagBytes: ber[tagStart:tagEnd],
@@ -243,9 +250,23 @@ func readObject(ber []byte, offset int) (asn1Object, int, error) {
 		}
 	}
 
-	return obj, contentEnd + hack, nil
+	// Apply indefinite form length with 0x0000 terminator.
+	if indefinite {
+		contentEnd = offset + 2
+	}
+
+	return obj, contentEnd, nil
+}
+
+func isIndefiniteTermination(ber []byte, offset int) (bool, error) {
+	if len(ber) - offset < 2 {
+		return false, errors.New("ber2der: Invalid BER format")
+	}
+
+	return bytes.Index(ber[offset:], []byte{0x0, 0x0}) == 0, nil
 }
 
 func debugprint(format string, a ...interface{}) {
 	//fmt.Printf(format, a)
 }
+
diff --git a/builtin/credential/aws/pkcs7/ber_test.go b/builtin/credential/aws/pkcs7/ber_test.go
index fcb4b6a24..169c78ab7 100644
--- a/builtin/credential/aws/pkcs7/ber_test.go
+++ b/builtin/credential/aws/pkcs7/ber_test.go
@@ -3,6 +3,8 @@ package pkcs7
 import (
 	"bytes"
 	"encoding/asn1"
+	"encoding/pem"
+	"fmt"
 	"strings"
 	"testing"
 )
@@ -45,7 +47,8 @@ func TestBer2Der_Negatives(t *testing.T) {
 		{[]byte{0x30, 0x85}, "tag length too long"},
 		{[]byte{0x30, 0x84, 0x80, 0x0, 0x0, 0x0}, "length is negative"},
 		{[]byte{0x30, 0x82, 0x0, 0x1}, "length has leading zero"},
-		{[]byte{0x30, 0x80, 0x1, 0x2}, "Invalid BER format"},
+		{[]byte{0x30, 0x80, 0x1, 0x2, 0x1, 0x2}, "Invalid BER format"},
+		{[]byte{0x30, 0x80, 0x1, 0x2}, "BER tag length is more than available data"},
 		{[]byte{0x30, 0x03, 0x01, 0x02}, "length is more than available data"},
 		{[]byte{0x30}, "end of ber data reached"},
 	}
@@ -60,3 +63,88 @@ func TestBer2Der_Negatives(t *testing.T) {
 		}
 	}
 }
+
+func TestVerifyIndefiniteLengthBer(t *testing.T) {
+	decoded := mustDecodePEM([]byte(testPKCS7))
+
+	_, err := ber2der(decoded)
+	if err != nil {
+		t.Errorf("cannot parse indefinite length ber: %v", err)
+	}
+}
+
+func mustDecodePEM(data []byte) []byte {
+	var block *pem.Block
+	block, rest := pem.Decode(data)
+	if len(rest) != 0 {
+		panic(fmt.Errorf("unexpected remaining PEM block during decode"))
+	}
+	return block.Bytes
+}
+
+const testPKCS7 = `
+-----BEGIN PKCS7-----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+-----END PKCS7-----
+`
diff --git a/changelog/12519.txt b/changelog/12519.txt
new file mode 100644
index 000000000..df383b9c9
--- /dev/null
+++ b/changelog/12519.txt
@@ -0,0 +1,3 @@
+```release-note:bug
+auth/aws: Fix ec2 auth on instances that have a cert in their PKCS7 signature
+```