From 94036bddb2030866574eefab8a0ad83dfe6a9a97 Mon Sep 17 00:00:00 2001
From: Felix Buschbeck <felixb15@proton.me>
Date: Mon, 3 Jun 2024 13:14:33 -0400
Subject: [PATCH] Fix null byte addition during variable lookup

---
 src/main/java/de/usd/cstchef/Utils.java | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/main/java/de/usd/cstchef/Utils.java b/src/main/java/de/usd/cstchef/Utils.java
index 1e99477..9686145 100644
--- a/src/main/java/de/usd/cstchef/Utils.java
+++ b/src/main/java/de/usd/cstchef/Utils.java
@@ -217,8 +217,11 @@ public static HttpRequest addCookieToHttpRequest(HttpRequest request, Cookie coo
     }
 
     public static ByteArray insertAtOffset(ByteArray input, int start, int end, ByteArray newValue) {
-        ByteArray prefix = BurpUtils.subArray(input, 0, start);
-        ByteArray rest = BurpUtils.subArray(input, end, input.length());
+        ByteArray prefix = input.subArray(0, start);
+        ByteArray rest = input.subArray(0, 0);
+        if(end < input.length()) {
+            rest = input.subArray(end, input.length());
+        }
         
         ByteArray output = prefix.withAppended(newValue).withAppended(rest);
         return output;