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Java: Match mixed-case weak cryptographic algorithm strings #23027

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400d4c4
fix(java): match mixed-case weak crypto algorithm strings
sam-robson Nov 5, 2026
fbcefd3
fix(java): match RSA prefix case-insensitively in RsaWithoutOaepQuery
sam-robson Nov 5, 2026
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4 changes: 4 additions & 0 deletions java/ql/lib/change-notes/2026-11-05-weak-crypto-case-sensitivity.md
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@@ -0,0 +1,4 @@
---
category: minorAnalysis
---
* The `java/weak-cryptographic-algorithm`, `java/potentially-weak-cryptographic-algorithm`, and `java/rsa-without-oaep` queries now match cryptographic algorithm names and modes case-insensitively (for example, `AES/CBC/PKCS5PADDING` and `AES/cbc/Pkcs5Padding`).
2 changes: 1 addition & 1 deletion java/ql/lib/semmle/code/java/security/BrokenCryptoAlgorithmQuery.qll
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Expand Up @@ -17,7 +17,7 @@ class BrokenAlgoLiteral extends ShortStringLiteral {
BrokenAlgoLiteral() {
this.getValue().regexpMatch(getInsecureAlgorithmRegex()) and
// Exclude RSA/ECB/.* ciphers.
not this.getValue().regexpMatch("RSA/ECB.*") and
not this.getValue().regexpMatch("(?i)RSA/ECB.*") and
// Exclude German and French sentences.
not this.getValue().regexpMatch(".*\\p{IsLowercase} des \\p{IsLetter}.*")
}
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9 changes: 6 additions & 3 deletions java/ql/lib/semmle/code/java/security/Encryption.qll
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Expand Up @@ -189,15 +189,18 @@ bindingset[algorithmString]
private string algorithmRegex(string algorithmString) {
// Algorithms usually appear in names surrounded by characters that are not
// alphabetical characters in the same case. This handles the upper and lower
// case cases.
// case cases, plus mixed-case algorithm strings bounded by non-alphabetic
// characters (such as `AES/cbc/Pkcs5Padding`).
result =
"((^|.*[^A-Z])(" + algorithmString + ")([^A-Z].*|$))" +
// or...
"|" +
// For lowercase, we want to be careful to avoid being confused by camelCase
// hence we require two preceding uppercase letters to be sure of a case switch,
// or a preceding non-alphabetic character
"((^|.*[A-Z]{2}|.*[^a-zA-Z])(" + algorithmString.toLowerCase() + ")([^a-z].*|$))"
"((^|.*[A-Z]{2}|.*[^a-zA-Z])(" + algorithmString.toLowerCase() + ")([^a-z].*|$))" +
// or...
"|" + "((^|.*[^a-zA-Z])(?i)(" + algorithmString + ")([^a-zA-Z].*|$))"
}

/**
Expand Down Expand Up @@ -258,7 +261,7 @@ string getInsecureAlgorithmReason(string input) {
string getASecureAlgorithmName() {
result =
[
"RSA", "SHA-?(256|384|512)", "CCM", "GCM", "AES(?![^a-zA-Z](ECB|CBC/PKCS[57]Padding))",
"RSA", "SHA-?(256|384|512)", "CCM", "GCM", "AES(?![^a-zA-Z](?i)(ECB|CBC/PKCS[57]Padding))",
"Blowfish", "ECIES", "SHA3-(256|384|512)",
// Elliptic Curve algorithms: EC (key generation), ECDSA (signatures), ECDH (key agreement),
// EdDSA/Ed25519/Ed448 (Edwards-curve signatures), XDH/X25519/X448 (key agreement).
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2 changes: 1 addition & 1 deletion java/ql/lib/semmle/code/java/security/RsaWithoutOaepQuery.qll
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Expand Up @@ -10,7 +10,7 @@ import semmle.code.java.dataflow.DataFlow
module RsaWithoutOaepConfig implements DataFlow::ConfigSig {
predicate isSource(DataFlow::Node src) {
exists(CompileTimeConstantExpr specExpr, string spec |
specExpr.getStringValue() = spec and
specExpr.getStringValue().toUpperCase() = spec and
specExpr = src.asExpr() and
spec.matches("RSA/%") and
not spec.matches("%OAEP%")
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8 changes: 8 additions & 0 deletions java/ql/test/query-tests/security/CWE-327/semmle/tests/BrokenCryptoAlgorithm.expected
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@@ -1,8 +1,16 @@
#select
| Test.java:19:20:19:50 | getInstance(...) | Test.java:19:45:19:49 | "DES" | Test.java:19:45:19:49 | "DES" | Cryptographic algorithm $@ is insecure. It has a short key length of 56 bits, making it vulnerable to brute-force attacks. Consider using AES instead. | Test.java:19:45:19:49 | "DES" | DES |
| Test.java:42:14:42:38 | getInstance(...) | Test.java:42:33:42:37 | "RC2" | Test.java:42:33:42:37 | "RC2" | Cryptographic algorithm $@ is insecure. It is vulnerable to related-key attacks. Consider using AES instead. | Test.java:42:33:42:37 | "RC2" | RC2 |
| Test.java:46:14:46:55 | getInstance(...) | Test.java:46:33:46:54 | "AES/CBC/PKCS5Padding" | Test.java:46:33:46:54 | "AES/CBC/PKCS5Padding" | Cryptographic algorithm $@ is insecure. CBC mode with PKCS#5 or PKCS#7 padding is vulnerable to padding oracle attacks. Consider using GCM instead. | Test.java:46:33:46:54 | "AES/CBC/PKCS5Padding" | AES/CBC/PKCS5Padding |
| Test.java:47:14:47:55 | getInstance(...) | Test.java:47:33:47:54 | "AES/CBC/PKCS5PADDING" | Test.java:47:33:47:54 | "AES/CBC/PKCS5PADDING" | Cryptographic algorithm $@ is insecure. CBC mode with PKCS#5 or PKCS#7 padding is vulnerable to padding oracle attacks. Consider using GCM instead. | Test.java:47:33:47:54 | "AES/CBC/PKCS5PADDING" | AES/CBC/PKCS5PADDING |
| Test.java:48:14:48:55 | getInstance(...) | Test.java:48:33:48:54 | "aes/cbc/pkcs5padding" | Test.java:48:33:48:54 | "aes/cbc/pkcs5padding" | Cryptographic algorithm $@ is insecure. CBC mode with PKCS#5 or PKCS#7 padding is vulnerable to padding oracle attacks. Consider using GCM instead. | Test.java:48:33:48:54 | "aes/cbc/pkcs5padding" | aes/cbc/pkcs5padding |
| Test.java:49:14:49:55 | getInstance(...) | Test.java:49:33:49:54 | "AES/cbc/Pkcs5Padding" | Test.java:49:33:49:54 | "AES/cbc/Pkcs5Padding" | Cryptographic algorithm $@ is insecure. CBC mode with PKCS#5 or PKCS#7 padding is vulnerable to padding oracle attacks. Consider using GCM instead. | Test.java:49:33:49:54 | "AES/cbc/Pkcs5Padding" | AES/cbc/Pkcs5Padding |
edges
nodes
| Test.java:19:45:19:49 | "DES" | semmle.label | "DES" |
| Test.java:42:33:42:37 | "RC2" | semmle.label | "RC2" |
| Test.java:46:33:46:54 | "AES/CBC/PKCS5Padding" | semmle.label | "AES/CBC/PKCS5Padding" |
| Test.java:47:33:47:54 | "AES/CBC/PKCS5PADDING" | semmle.label | "AES/CBC/PKCS5PADDING" |
| Test.java:48:33:48:54 | "aes/cbc/pkcs5padding" | semmle.label | "aes/cbc/pkcs5padding" |
| Test.java:49:33:49:54 | "AES/cbc/Pkcs5Padding" | semmle.label | "AES/cbc/Pkcs5Padding" |
subpaths
7 changes: 7 additions & 0 deletions java/ql/test/query-tests/security/CWE-327/semmle/tests/Test.java
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Expand Up @@ -41,6 +41,13 @@ public void test() {
// BAD: RC2 is a weak algorithm
cipher = Cipher.getInstance("RC2"); // $ Alert[java/weak-cryptographic-algorithm]
}
{
// BAD: AES/CBC/PKCS5Padding is vulnerable to padding oracle attacks, regardless of case
cipher = Cipher.getInstance("AES/CBC/PKCS5Padding"); // $ Alert[java/weak-cryptographic-algorithm]
cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING"); // $ Alert[java/weak-cryptographic-algorithm]
cipher = Cipher.getInstance("aes/cbc/pkcs5padding"); // $ Alert[java/weak-cryptographic-algorithm]
cipher = Cipher.getInstance("AES/cbc/Pkcs5Padding"); // $ Alert[java/weak-cryptographic-algorithm]
}
// GOOD: ECIES is a strong algorithm
cipher = Cipher.getInstance("ECIES");
cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec);
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14 changes: 8 additions & 6 deletions java/ql/test/query-tests/security/CWE-780/RsaWithoutOaepTest.expected
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@@ -1,12 +1,14 @@
#select
| RsaWithoutOaepTest.java:5:44:5:62 | "RSA/ECB/NoPadding" | RsaWithoutOaepTest.java:5:44:5:62 | "RSA/ECB/NoPadding" | RsaWithoutOaepTest.java:5:44:5:62 | "RSA/ECB/NoPadding" | This specification is used to $@ without OAEP padding. | RsaWithoutOaepTest.java:5:44:5:62 | "RSA/ECB/NoPadding" | initialize an RSA cipher |
| RsaWithoutOaepTest.java:15:32:15:50 | "RSA/ECB/NoPadding" : String | RsaWithoutOaepTest.java:15:32:15:50 | "RSA/ECB/NoPadding" : String | RsaWithoutOaepTest.java:11:35:11:38 | spec | This specification is used to $@ without OAEP padding. | RsaWithoutOaepTest.java:11:35:11:38 | spec | initialize an RSA cipher |
| RsaWithoutOaepTest.java:6:49:6:67 | "rsa/ECB/NoPadding" | RsaWithoutOaepTest.java:6:49:6:67 | "rsa/ECB/NoPadding" | RsaWithoutOaepTest.java:6:49:6:67 | "rsa/ECB/NoPadding" | This specification is used to $@ without OAEP padding. | RsaWithoutOaepTest.java:6:49:6:67 | "rsa/ECB/NoPadding" | initialize an RSA cipher |
| RsaWithoutOaepTest.java:17:32:17:50 | "RSA/ECB/NoPadding" : String | RsaWithoutOaepTest.java:17:32:17:50 | "RSA/ECB/NoPadding" : String | RsaWithoutOaepTest.java:13:35:13:38 | spec | This specification is used to $@ without OAEP padding. | RsaWithoutOaepTest.java:13:35:13:38 | spec | initialize an RSA cipher |
edges
| RsaWithoutOaepTest.java:10:29:10:39 | spec : String | RsaWithoutOaepTest.java:11:35:11:38 | spec | provenance | |
| RsaWithoutOaepTest.java:15:32:15:50 | "RSA/ECB/NoPadding" : String | RsaWithoutOaepTest.java:10:29:10:39 | spec : String | provenance | |
| RsaWithoutOaepTest.java:12:29:12:39 | spec : String | RsaWithoutOaepTest.java:13:35:13:38 | spec | provenance | |
| RsaWithoutOaepTest.java:17:32:17:50 | "RSA/ECB/NoPadding" : String | RsaWithoutOaepTest.java:12:29:12:39 | spec : String | provenance | |
nodes
| RsaWithoutOaepTest.java:5:44:5:62 | "RSA/ECB/NoPadding" | semmle.label | "RSA/ECB/NoPadding" |
| RsaWithoutOaepTest.java:10:29:10:39 | spec : String | semmle.label | spec : String |
| RsaWithoutOaepTest.java:11:35:11:38 | spec | semmle.label | spec |
| RsaWithoutOaepTest.java:15:32:15:50 | "RSA/ECB/NoPadding" : String | semmle.label | "RSA/ECB/NoPadding" : String |
| RsaWithoutOaepTest.java:6:49:6:67 | "rsa/ECB/NoPadding" | semmle.label | "rsa/ECB/NoPadding" |
| RsaWithoutOaepTest.java:12:29:12:39 | spec : String | semmle.label | spec : String |
| RsaWithoutOaepTest.java:13:35:13:38 | spec | semmle.label | spec |
| RsaWithoutOaepTest.java:17:32:17:50 | "RSA/ECB/NoPadding" : String | semmle.label | "RSA/ECB/NoPadding" : String |
subpaths
2 changes: 2 additions & 0 deletions java/ql/test/query-tests/security/CWE-780/RsaWithoutOaepTest.java
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Expand Up @@ -3,8 +3,10 @@
class RsaWithoutOaep {
public void test() throws Exception {
Cipher rsaBad = Cipher.getInstance("RSA/ECB/NoPadding"); // $ Alert
Cipher rsaBadLower = Cipher.getInstance("rsa/ECB/NoPadding"); // $ Alert

Cipher rsaGood = Cipher.getInstance("RSA/ECB/OAEPWithSHA-1AndMGF1Padding");
Cipher rsaGoodLower = Cipher.getInstance("rsa/ecb/oaepwithsha-1andmgf1padding");
}

public Cipher getCipher(String spec) throws Exception {
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