---
title: ECB mode is insecure
description: Datadog, the leading service for cloud-scale monitoring.
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  Docs > Datadog Security > Code Security > Static Code Analysis (SAST) > SAST
  Rules > ECB mode is insecure
---

# ECB mode is insecure

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# Important note for users on the following Datadog sites: app.ddog-gov.com

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This product is not supported for your selected [Datadog site](https://docs.datadoghq.com/getting_started/site). ().
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{% /callout %}

## Metadata{% #metadata %}

**ID:** `java-security/cipher-padding-oracle`

**Language:** Java

**Severity:** Error

**Category:** Security

**CWE**: [326](https://cwe.mitre.org/data/definitions/326.html)

**Related CWEs**:

- [328](https://cwe.mitre.org/data/definitions/328.html)

## Description{% #description %}

CBC mode used with `PKCS5Padding` is susceptible to padding attacks. Datadog recommends using `AES/GCM/NoPadding`.

#### Learn More{% #learn-more %}

- [Cipher is susceptible to Padding Oracle](https://find-sec-bugs.github.io/bugs.htm#PADDING_ORACLE)
- [CWE-326 - Inadequate Encryption Strength](https://cwe.mitre.org/data/definitions/326.html)

## Non-Compliant Code Examples{% #non-compliant-code-examples %}

```java
class MyClass {

    public void test1() {
        Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");
        c.init(Cipher.ENCRYPT_MODE, k, iv);
        byte[] cipherText = c.doFinal(plainText);
    }

    public void test2() {
        Cipher c = javax.crypto.Cipher.getInstance("AES/CBC/PKCS5Padding");
        c.init(Cipher.ENCRYPT_MODE, k, iv);
        byte[] cipherText = c.doFinal(plainText);
    }
}
```

## Compliant Code Examples{% #compliant-code-examples %}

```java
class MyClass {

    public void test() {
        Cipher c = Cipher.getInstance("AES/GCM/NoPadding");
        c.init(Cipher.ENCRYPT_MODE, k, iv);
        byte[] cipherText = c.doFinal(plainText);
    }

    public void test2() {
        Cipher c = javax.crypto.Cipher.getInstance("AES/GCM/NoPadding");
        c.init(Cipher.ENCRYPT_MODE, k, iv);
        byte[] cipherText = c.doFinal(plainText);
    }
}
```
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