CVE-2024-23617

Executive Summary

CVE-2024-23617 is a critical buffer overflow vulnerability in Symantec Data Loss Prevention (DLP) version 14.0.2 and earlier. This flaw allows a remote, unauthenticated attacker to achieve arbitrary code execution by enticing a user to open a specially crafted document. The vulnerability resides in the document parsing engine of the DLP agent, which fails to properly validate input length during processing. With a CVSS score of 9.6, this vulnerability poses a severe risk to enterprise environments where Symantec DLP is deployed for data protection. No public proof-of-concept or exploit code has been released, and no official patch is currently available, making this a high-priority zero-day threat.

CVSS Breakdown & Threat Level

• CVSS Score: 9.6 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required (victim opens crafted document)
• Scope: Changed
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

The high score reflects the ease of exploitation (low complexity, no privileges) and the severe impact on confidentiality, integrity, and availability. The changed scope indicates that the compromised component can affect resources beyond its original authorization.

Deep Dive & Mechanics

The vulnerability is a classic buffer overflow in the document parsing module of Symantec DLP. When the DLP agent processes a document (e.g., PDF, DOCX, or RTF), it copies data into a fixed-size buffer without proper bounds checking. An attacker can craft a document with an oversized field (e.g., metadata, embedded object, or custom property) that overflows the buffer, overwriting adjacent memory regions.

Exploitation Flow:

1. Attacker crafts a malicious document with a payload in an oversized field.
2. Attacker delivers the document via email, web download, or other means.
3. Victim opens the document on a system with Symantec DLP agent installed.
4. The DLP agent parses the document, triggering the buffer overflow.
5. The overflow overwrites the return address or function pointer, redirecting execution to attacker-controlled shellcode.
6. Shellcode executes with the privileges of the DLP agent (typically SYSTEM or high-integrity user).

The vulnerability is particularly dangerous because it requires no authentication and can be triggered by simply opening a document, a common user action.

Vulnerable vs. Patched Code

Since no patch is available, we can only analyze the vulnerable code pattern. The vulnerable code likely resembles:

// Vulnerable code (pseudocode)
void ParseDocumentField(char *input, int input_len) {
    char buffer[256];
    // No bounds check
    memcpy(buffer, input, input_len);
    // Process buffer...
}

A patched version would include proper bounds checking:

// Patched code (pseudocode)
void ParseDocumentField(char *input, int input_len) {
    char buffer[256];
    if (input_len > sizeof(buffer) - 1) {
        // Handle error or truncate
        return;
    }
    memcpy(buffer, input, input_len);
    // Process buffer...
}

The key difference is the addition of a length check before copying data into the fixed-size buffer.

Exploitation & Lab Setup

Red Team

Lab Setup:

• Target: Windows 10/11 with Symantec DLP 14.0.2 installed
• Attacker: Kali Linux with Metasploit and custom exploit tools
• Document: Crafted PDF/DOCX with overflow payload

Exploitation Steps:

1. Identify the vulnerable field in the document parser (e.g., document title, author, or custom property).
2. Create a buffer overflow payload:
   • NOP sled (0x90)
   • Shellcode (e.g., reverse shell or add user)
   • Return address pointing to shellcode
3. Embed payload in the oversized field of a document.
4. Deliver document to victim (e.g., via phishing email).
5. When victim opens document, exploit triggers and shellcode executes.

Example Payload Structure:

[Padding (A's)] [Return Address] [NOP Sled] [Shellcode]

Note: Since no public exploit exists, this is a theoretical approach. Actual exploitation requires reverse engineering the specific binary.

Blue Team

Detection & Response:

• Monitor for abnormal document processing by Symantec DLP processes (e.g., dlpagent.exe or symdlp.exe).
• Look for crashes or memory access violations in DLP logs.
• Use endpoint detection and response (EDR) to detect shellcode execution or unusual process behavior.
• Block suspicious documents at email gateway or web proxy.

Hunting Queries:

• Event ID 1000 (Application Crash) for DLP processes.
• Process creation events where DLP agent spawns cmd.exe or powershell.exe.
• Network connections from DLP agent to unknown IPs.

Indicators of Compromise (IOCs)

• File Hashes: (No known samples yet)
• Network Indicators: C2 IPs/domains used in shellcode (unknown)
• Process Names: dlpagent.exe, symdlp.exe, symantecdlp.exe
• Registry Keys: HKLM\SOFTWARE\Symantec\DLP\Agent
• YARA Rule: See Detection Engineering section

Detection Engineering

YARA Rule

rule CVE_2024_23617_Symantec_DLP_BufferOverflow {
    meta:
        description = "Detects crafted documents exploiting CVE-2024-23617 in Symantec DLP"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-23617"
    strings:
        $s1 = "Symantec DLP" ascii wide nocase
        $s2 = "dlpagent" ascii wide nocase
        $overflow_pattern = { 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 41 } // 16 A's
    condition:
        $s1 or $s2 and #overflow_pattern > 10
}

Sigma Rule

title: CVE-2024-23617 Symantec DLP Buffer Overflow Exploitation
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential exploitation of CVE-2024-23617 via document parsing
author: Valters IT
date: 2024-01-01
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith:
            - '\dlpagent.exe'
            - '\symdlp.exe'
        CommandLine|contains:
            - 'cmd.exe'
            - 'powershell.exe'
            - 'rundll32.exe'
    condition: selection
falsepositives:
    - Legitimate administrative use
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (msg:"CVE-2024-23617 Symantec DLP Exploit - Suspicious Document Download"; flow:to_server,established; content:"Content-Type|3a| application/"; http_header; content:"Content-Disposition|3a| attachment"; http_header; fileext:"pdf" or fileext:"docx" or fileext:"rtf"; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected systems: Disconnect Symantec DLP agents from the network if possible.
2. Block document types: Temporarily block PDF, DOCX, and RTF files at email gateway and web proxy.
3. User awareness: Train users not to open documents from untrusted sources.
4. Monitor logs: Enable detailed logging for DLP agent crashes and document processing.

Long-term Fix:

• Await official patch from Symantec (Broadcom). Monitor Symantec security advisories.
• Consider replacing Symantec DLP with an alternative solution if patch is delayed.
• Implement application whitelisting to prevent unauthorized executables.

Workaround:

• Disable document parsing features in DLP agent configuration if possible.
• Use Group Policy to restrict DLP agent permissions.

Valters IT
Securing Digital Frontiers