CVE-2025-48708

Executive Summary

CVE-2025-48708 is a cleartext storage of sensitive information vulnerability in Artifex Ghostscript, a widely used interpreter for PostScript and PDF files. The flaw resides in the gs_lib_ctx_stash_sanitized_arg function within base/gslibctx.c. When processing a crafted PDF document that includes a password (specifically for the # case), the password is not properly sanitized and is stored in cleartext in memory. This could allow an attacker with local access to the system to retrieve the password from memory dumps or process listings, leading to unauthorized access to protected documents. The vulnerability has a CVSS score of 4.0 (Medium) and affects versions prior to 10.05.1. No public proof-of-concept or exploit code is available at this time.

Supply Chain & Package Security

This vulnerability is not in a package manager ecosystem (NPM, PyPI, Go, Ruby) but is a core component of the Ghostscript software, which is often distributed as a system package or bundled with other applications. Organizations should verify the version of Ghostscript in their software supply chain and ensure it is updated to 10.05.1 or later.

CVSS Breakdown & Threat Level

• CVSS Score: 4.0 (Medium)
• Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
• Attack Vector (AV): Local (L) – The attacker must have local access to the system.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – No privileges are needed to trigger the vulnerability.
• User Interaction (UI): Required (R) – The victim must open a crafted PDF file.
• Scope (S): Unchanged (U) – The vulnerability does not affect other components.
• Confidentiality (C): High (H) – The password is exposed in cleartext.
• Integrity (I): None (N) – No data integrity impact.
• Availability (A): None (N) – No availability impact.

Threat Level: Medium. The vulnerability requires local access and user interaction, but the impact on confidentiality is high as it exposes document passwords.

Deep Dive & Mechanics

The vulnerability is located in the gs_lib_ctx_stash_sanitized_arg function in base/gslibctx.c. This function is responsible for sanitizing arguments passed to the Ghostscript library context. The issue arises when handling the # case in PDF password processing. Specifically, when a PDF document is opened with a password, the password is supposed to be sanitized (e.g., cleared from memory) after use. However, due to a missing sanitization step for the # case, the password remains in cleartext in the memory buffer.

The root cause is a logic error in the sanitization routine. The function iterates over arguments and attempts to clear sensitive data, but the # case is not handled, leaving the password intact. This can be exploited by an attacker who can read the process memory of Ghostscript (e.g., via /proc/ on Linux or a memory dump) after a user opens a malicious PDF.

The attack flow:

1. An attacker crafts a PDF document that requires a password to open.
2. The attacker tricks a victim into opening the PDF with Ghostscript.
3. The victim enters the password (or the PDF is opened with a password from a script).
4. Ghostscript processes the password but fails to sanitize it for the # case.
5. The password remains in cleartext in the process memory.
6. The attacker, with local access, reads the process memory and extracts the password.

Vulnerable vs. Patched Code

Vulnerable Code (before 10.05.1):

// base/gslibctx.c
static void
gs_lib_ctx_stash_sanitized_arg(gs_lib_ctx_t *ctx, const char *arg)
{
    // ... other cases ...
    if (arg[0] == '#') {
        // Missing sanitization - password is not cleared
        // The password remains in memory
    }
    // ... other cases ...
}

Patched Code (10.05.1 and later):

// base/gslibctx.c
static void
gs_lib_ctx_stash_sanitized_arg(gs_lib_ctx_t *ctx, const char *arg)
{
    // ... other cases ...
    if (arg[0] == '#') {
        // Properly sanitize the password by overwriting it
        memset((void *)arg, 0, strlen(arg));
    }
    // ... other cases ...
}

The patch adds a memset call to overwrite the password buffer with zeros, ensuring the password is cleared from memory after use.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Local access to the target system.
• A victim user who opens a crafted PDF with Ghostscript.
• Ability to read process memory (e.g., /proc/<pid>/mem on Linux).

Steps:

1. Create a malicious PDF that requires a password. For example, using a tool like qpdf:

   qpdf --encrypt mypassword 256 -- myinput.pdf malicious.pdf
   

2. Deliver the PDF to the victim (e.g., via email or file share).
3. When the victim opens the PDF with Ghostscript (e.g., gs malicious.pdf), the password is stored in cleartext in memory.
4. As an attacker with local access, identify the PID of the Ghostscript process:

   ps aux | grep gs
   

5. Dump the process memory:

   sudo gdb -p <PID> -batch -ex "dump memory /tmp/gs_mem.dump 0x0 0x7fffffffffffffff"
   

6. Search for the password in the memory dump:

   strings /tmp/gs_mem.dump | grep mypassword
   

Note: No public exploit code is available. The above is a conceptual demonstration.

Blue Team (Detection & Defense)

Detection:

• Monitor for unusual Ghostscript processes opening PDFs with passwords.
• Use process auditing to detect memory dumping tools (e.g., gdb, dd, memdump).
• Implement endpoint detection and response (EDR) rules for cleartext password storage.

Defense:

• Upgrade to Ghostscript 10.05.1 or later.
• Restrict local access to systems running Ghostscript.
• Use memory protection mechanisms (e.g., SELinux, AppArmor) to limit process memory access.
• Educate users not to open PDFs from untrusted sources.

Indicators of Compromise (IOCs)

• File Hashes: (No specific hashes available; monitor for PDFs with embedded passwords)
• Process Names: gs, ghostscript, gswin32c, gswin64c
• Memory Artifacts: Cleartext passwords in process memory (e.g., strings containing # followed by password)
• Network: No network indicators (local vulnerability)
• Logs: Ghostscript logs may show password usage (e.g., -sPDFPassword=...)

Detection Engineering

YARA Rule

rule CVE_2025_48708_Ghostscript_Cleartext_Password {
    meta:
        description = "Detects cleartext password storage in Ghostscript process memory"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-48708"
    strings:
        $password_pattern = /#[A-Za-z0-9!@#$%^&*()_+=-]{1,64}/
    condition:
        $password_pattern
}

Sigma Rule

title: Ghostscript Cleartext Password in Memory
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential exploitation of CVE-2025-48708 where Ghostscript stores passwords in cleartext
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: linux
detection:
    selection:
        Image|endswith: '/gs'
        CommandLine|contains: 'PDFPassword'
    condition: selection
falsepositives:
    - Legitimate use of Ghostscript with passwords
level: medium

Suricata Rule

alert tcp any any -> any any (msg:"CVE-2025-48708 Ghostscript Cleartext Password"; flow:to_server; content:"PDFPassword"; nocase; sid:1000001; rev:1;)

Note: The Suricata rule is for network detection of password transmission, though the vulnerability is local. Adjust as needed.

Remediation & Mitigation

Immediate:

• Upgrade Ghostscript to version 10.05.1 or later.
• If upgrade is not possible, restrict local access to Ghostscript processes.

Long-term:

• Implement memory sanitization best practices in custom software.
• Use memory-safe languages or libraries for sensitive data handling.
• Regularly audit software for CWE-312 (Cleartext Storage of Sensitive Information).

Workarounds:

• Avoid opening PDFs with passwords from untrusted sources.
• Use alternative PDF viewers that do not store passwords in cleartext.

Valters IT
Securing Digital Frontiers