Exploiting Ivanti Connect Secure RCE (CVE-2025-0282)

Exploiting Ivanti Connect Secure RCE (CVE-2025-0282)

Overview

A recently disclosed vulnerability in Ivanti Connect Secure (CVE-2025-0282) has revealed a stack-based buffer overflow that enables remote code execution (RCE) without authentication. This flaw, found in the VPN appliance’s handling of IF-T connections, raises significant concerns about enterprise security, especially for organizations relying on Ivanti for secure remote access.

In this post, we’ll break down the root cause, discuss the stack layout, and walk through how exploitation could be achieved. However, in the interest of responsible disclosure, we won’t be providing a fully weaponized proof of concept.

Root Cause Analysis

At the core of this vulnerability is improper memory handling in /home/bin/web, the binary responsible for managing incoming HTTP and VPN protocol requests. Specifically, the issue lies in how the application processes the clientCapabilities parameter.

The Critical Mistake

While the function responsible for handling these connections does attempt to use strncpy() instead of the unsafe strcpy(), the incorrect size parameter was passed. Instead of restricting input based on the destination buffer’s size, it mistakenly used the input string’s length. This means that any input longer than 256 bytes will overwrite adjacent stack variables—including the return address.

clientCapabilities = getKey(req, "clientCapabilities");
if (clientCapabilities != NULL) {
    clientCapabilitiesLength = strlen(clientCapabilities);
    if (clientCapabilitiesLength != 0) {
        connInfo->clientCapabilities = clientCapabilities;
    }
}
memset(dest, 0, sizeof(dest));
strncpy(dest, connInfo->clientCapabilities, clientCapabilitiesLength);

The flaw is straightforward: the dest buffer is only 256 bytes, yet the function allows clientCapabilitiesLength to be greater than 256, causing an out-of-bounds write.

Stack Layout and Control Flow

To understand how this overflow can be leveraged for exploitation, let’s examine the stack layout at the time of execution:

+---------------------+
| v18 (int)          |
+---------------------+
| v19 (int)          |
+---------------------+
| dest[256]          | <- Buffer Overflow Occurs Here
+---------------------+
| object_to_be_freed |
+---------------------+
| ptr (void *)       |
+---------------------+
| v20 (int)          |
+---------------------+
| v21 (int)          |
+---------------------+
| v22 (int)          |
+---------------------+
| v23 (char)         |
+---------------------+
| v24 (char)         |
+---------------------+
| v25 (void *)       |
+---------------------+
| v26[499]           |
+---------------------+
| Return Address     | <- Overwritten to Control Execution Flow
+---------------------+

Under normal conditions, an attacker could overwrite the return address and redirect execution to controlled shellcode or a ROP chain. However, there’s a problem—the function attempts to free a stack-allocated object before returning, which triggers a crash if the pointer has been corrupted.

Exploitation Strategy

Leveraging VTables for Control To avoid premature crashes, we can redirect execution via a virtual function table (vtable) pointer instead of directly overwriting the return address. This works by:

1. Overwriting the this pointer stored on the stack.
2. Redirecting it to a fake vtable placed in a controlled memory region.
3. Ensuring the virtual function at offset 0x48 points to a useful ROP gadget. This technique allows us to bypass the function epilogue that would normally dereference invalid memory and cause a segmentation fault.

Crafting a ROP Chain

Once control is established, the next step is building a Return-Oriented Programming (ROP) chain to achieve code execution. A typical approach might look like this:

mov_eax_esp_ret = p32(0xf29e92c3)   # mov eax, esp; ret
add_eax_8_ret = p32(0xf5068858)     # add eax, 8; ret;
pop_esi_ret = p32(0xf4f5de27)       # pop esi; ret;
esi = p32(0xf5a07d40)               # system
set_arg_call_esi = p32(0xf4f5e265)  # mov dword ptr [esp], eax; call esi;

This sequence sets up system("/bin/sh"), achieving remote shell access.

Challenges and Mitigations

While this vulnerability is exploitable under the right conditions, certain defenses complicate exploitation:

• ASLR & PIE: The binary is position-independent, meaning addresses are randomized each execution.
• Stack Canaries: If enabled, canaries will detect buffer overflows before the return address is overwritten.
• Non-Executable Stack: Shellcode injection alone won’t work without ROP or JOP (Jump-Oriented Programming).

However, ASLR is limited in x86 architectures, making brute-force feasible in certain environments. A full exploit would require leaking memory addresses or brute-forcing ASLR offsets.

Conclusion

This vulnerability in Ivanti Connect Secure (CVE-2025-0282) exposes a serious risk for organizations using the VPN appliance. While Ivanti has since released patches, the fact that such a fundamental buffer overflow was present in a mission-critical security product raises concerns.

This case underscores the importance of secure coding practices, proper memory handling, and proactive security testing. Enterprises should ensure:

Immediate patching of affected appliances. Stronger security validation during product development. Continuous security testing to catch these issues before attackers do.

Take Action

If your organization uses Ivanti Connect Secure, ensure that:

• Firmware is updated to the latest version.
• Network segmentation prevents direct exposure of the VPN appliance.
• Anomaly detection is enabled for unexpected VPN activity.